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Chapter 64 - Agriculture and Natural Resources Based Industries

GENERAL PROFILE

Melvin L. Myers

Overview

Twelve millennia ago, humankind moved into the Neolithic era and discovered that food, feed and fibre could be produced from the cultivation of plants. This discovery has led to the food and fibre supply that feeds and clothes more than 5 billion people today.

This general profile of the agricultural industry includes its evolution and structure, economic importance of different crop commodities and characteristics of the industry and workforce. Agricultural workforce systems involve three types of major activities:

1.     manual operations

2.     mechanization

3.     draught power, provided specifically by those engaged in livestock rearing, which is discussed in the chapter Livestock rearing.

The agriculture system is shown as four major processes. These processes represent sequential phases in crop production. The agricultural system produces food, feed and fibre as well as consequences for occupational health and, more generally, public health and the environment.

Major commodities, such as wheat or sugar, are outputs from agriculture that are used as food, animal feed or fibre. They are represented in this chapter by a series of articles that address processes, occupational hazards and preventive actions specific to each commodity sector. Animal feed and forage are discussed in the chapter Livestock rearing.

Evolution and Structure of the Industry

The Neolithic revolution—the change from hunting and gathering to farming—started in three different places in the world. One was west and southwest of the Caspian Sea, another was in Central America and a third was in Thailand near the Burmese border. Agriculture started in about 9750 BC at the latter location, where seeds of peas, beans, cucumbers and water chestnuts have been found. This was 2,000 years before true agriculture was discovered in the other two regions. The essence of the Neolithic revolution and, thus, agriculture is the harvesting of plant seeds, their reintroduction into the soil and cultivation for another harvest.

In the lower Caspian area, wheat was the early crop of choice. As farmers migrated, taking wheat seed with them, the weeds in other regions were discovered to also be edible. These included rye and oats. In Central America, where maize and beans were the staples, the tomato weed was found to bear nutritious food.

Agriculture brought with it several problems:

·     Weeds and other pests (insects in the fields and mice and rats in the granaries) became a problem.

·     Early agriculture concerned itself with taking all that it could from the soil, and it would take 50 years to naturally replenish the soil.

·     In some places, the stripping of growth from the soil would turn the land to desert. To provide water to crops, farmers discovered irrigation about 7,000 years ago.

Solutions to these problems have led to new industries. Ways to control weeds, insects and rodents evolved into the pesticide industry, and the need to replenish the soil has resulted in the fertilizer industry. The need to provide water for irrigation has spawned systems of reservoirs and networks of pipes, canals and ditches.

Agriculture in the developing nations consists principally of family-owned plots. Many of these plots have been handed down from generation to generation. Peasants make up half of the world’s rural poor, but they produce four-fifths of the developing countries’ food supply. In contrast, farms are increasing in size in the developed countries, turning agriculture into large-scale commercial operations, where production is integrated with processing, marketing and distribution in an agribusiness system (Loftas 1995).

Agriculture has provided subsistence for farmers and their families for centuries, and it has recently changed into a system of production agriculture. A series of “revolutions” has contributed to an increase in agricultural production. The first of these was the mechanization of agriculture, whereby machines in the fields substituted for manual labour. The second was the chemical revolution that, after the Second World War, contributed to the control of pests in agriculture, but with environmental consequences. A third was the green revolution, which contributed to North American and Asian productivity growth through genetic advances in the new varieties of crops.

Economic Importance

The human population has grown from 2.5 billion in 1950 to 5.6 billion in 1994, and the United Nations estimates that it will continue to grow to 7.9 billion by 2025. The continued rise in the human population will increase the demand for food energy and nutrients, both because of the increase in numbers of people and the global drive to combat malnutrition (Brown, Lenssen and Kane 1995). A list of nutrients derived from food is shown in table 64.1 .

Table 64.1 Sources of nutrients

Nutrient

Plant sources

Animal sources

Carbohydrates (sugars and starch)

Fruits, cereals, root vegetables, pulses

Honey, milk

Dietary fats

Oilseeds, nuts, and legumes

Meat, poultry, butter, ghee, fish

Proteins

Pulses, nuts, and cereals

Meat, fish, dairy products

Vitamins

Carotenes: carrots, mangoes, papaya

Vitamin C: fruits and vegetables

Vitamin B complex: cereals, legumes

Vitamin A: liver, eggs, milk

Vitamin B complex: meat, poultry, dairy products

Minerals

Calcium: peas, beans

Iron: dark green leafy vegetables and nuts

Calcium: milk, meat, cheese

Iron: meat, fish, shellfish

Source: Loftas 1995.

Agriculture today can be understood as an enterprise to provide subsistence for those doing the work, staples for the community in which the food is grown and income from the sale of commodities to an external market. A staple food is one that supplies a major part of energy and nutrient needs and constitutes a dominant part of the diet. Excluding animal products, most people live off of one or two of the following staples: rice, wheat, maize (corn), millet, sorghum, and roots and tubers (potatoes, cassava, yams and taro). Although there are 50,000 edible plant species in the world, only 15 provide 90% of the world’s food energy intake.

Cereals constitute the principal commodity category that the world depends upon for its staples. Cereals include wheat and rice, the principal food staples, and coarse grains, which are used for animal feed. Three—rice, maize and wheat—are staples to more than 4.0 billion people. Rice feeds about half of the world’s population (Loftas 1995).

Another basic food crop is the starchy foods: cassava, sweet potatoes, potatoes, yams, taro and plantains. More than 1 billion people in developing nations use roots and tubers as staples. Cassava is grown as a staple in developing countries for 500 million people. For some of these commodities, much of the production and consumption remains at the subsistence level.

An additional basic food crop is the pulses, which comprise a number of dry beans—peas, chickpeas and lentils; all are legumes. They are important for their starch and protein.

Other legumes are used as oil crops; they include soybeans and groundnuts. Additional oil crops, used to make vegetable oil, include coconuts, sesame, cotton seed, oil palm and olive. In addition, some maize and rice bran are used to make vegetable oil. Oil crops also have uses other than for food, such as in manufacturing paints and detergents (Alexandratos 1995).

Small landholders grow many of the same crops as plantation operations do. Plantation crops, typically thought of as tropical export commodities, include natural rubber, palm oil, cane sugar, tropical beverages (coffee, cocoa, tea), cotton, tobacco and bananas. They may include crops that are also grown for both local consumption and export, such as coffee and sugar cane (ILO 1994).

Urban agriculture is labour intensive, occurs on small plots and is present in developed as well as developing countries. In the United States, more than one-third of the dollar value of agricultural crops is produced in urban areas and agriculture may employ as much as 10% of the urban population. In contrast, up to 80% of the population in smaller Siberian and Asian cities may be employed in agricultural production and processing. An urban farmer’s produce may also be used for barter, such as paying a landlord (UNDP 1996).

Characteristics of the Industry and Workforce

The 1994 world population totalled 5,623,500,000, and 2,735,021,000 (49%) of this population was engaged in agriculture, as shown in figure 64.1 . The largest component of this workforce is in the developing nations and transitional economies. Less than 100 million are in the developed nations, where mechanization has added to their productivity.

Figure 64.1 Millions of people engaged in agriculture by world region (1994)

Farming employs men and women, young and old. Their roles vary; for example, women in sub-Saharan Africa produce and market 90% of locally grown food. Women are also given the task of growing the subsistence diet for their families (Loftas 1995).

Children become farm labourers around the world at an early age (figure 64.2), working typically 45 hours per week during harvesting operations. Child labour has been a part of plantation agriculture throughout its history, and a prevalent use of contract labour based upon compensation for tasks completed aggravates the problem of child labour. Whole families work to increase the task completion in order to sustain or increase their income.

Figure 64.2 Young boy working in agriculture in India

Data on plantation employment generally show that the highest incidence of poverty is among agricultural wage labourers working in commercial agriculture. Plantations are located in tropical and subtropical regions of the world, and living and working conditions there may aggravate health problems that accompany the poverty (ILO 1994).

Agriculture in urban areas is another important component of the industry. An estimated 200 million farmers work part-time—equivalent to 150 million full-time workers—in urban agriculture to produce food and other agricultural products for the market. When subsistence agriculture in urban areas is included, the total reaches 800 million (UNDP 1996).

Total agricultural employment by major world region is shown in figure 64.1 . In both the United States and Canada, a small proportion of the population is employed in agriculture, and farms are becoming fewer as operations consolidate. In Western Europe, agriculture has been characterized by smallholdings, a relic of equal division of the previous holding among the children. However, with the migration from agriculture, holdings in Europe have been increasing in size. Eastern Europe’s agriculture carries a history of socialized farming. The average farm size in the former USSR was more than 10,000 hectares, while in other Eastern European countries it was about one-third that size. This is changing as these countries move toward market economies. Many Asian countries have been modernizing their agricultural operations, with some countries achieving rice surpluses. More than 2 billion people remain engaged in agriculture in this region, and much of the increased production is attributed to high- production species of crops such as rice. Latin America is a diverse region where agriculture plays an important economic role. It has vast resources for agricultural use, which has been increasing, but at the expense of tropical forests. In both the Middle East and Africa, per capita food production has seen a decline. In the Middle East, the principal limiting factor on agriculture is the availability of water. In Africa, traditional farming depends upon small, 3- to 5-hectare plots, which are operated by women while the men are employed elsewhere, some in other countries to earn cash. Some countries are developing larger farming operations.

FAMILY FARMS

The family farm is an enterprise and a homestead on which both children and the elderly are likely to be present. In some parts of the world, farm families live in villages surrounded by their farm land. The family farm combines family relationships and child raising with the production of food and other raw materials. Family farms range from small, subsistence or part-time operations worked with draught animals and hand tools to very large, family-held corporations with numerous full-time employees. Types of family farms are distinguished by national, regional, cultural, historical, economic, religious and several other factors. The size and type of operations determine the demand for labour from family members and the need for hired full- or part-time workers. A typical farm operation may combine the tasks of livestock handling, manure disposal, grain storage, heavy equipment operation, pesticide application, machinery maintenance, construction and many other jobs.

The Organization for Economic Cooperation and Development (OECD 1994) reports several trends in agriculture, including:

1. the increasing economic dominance of large, highly mechanized producers

2. the increase in off-farm employment as the principal source of income for small farms

3. the controlling role of national and international agricultural policies and trade agreements.

The concentration of farm operations and the reduction in the number of family farms has been recognized for decades. These economic forces affect the work processes, workload and safety and health of the family farm. Several key changes are occurring in family farming as a direct result of these economic forces, including expanding workloads, increasing reliance on hired labor, use of new techniques, unsupervised adolescents and struggling to maintain economic viability.

Children nearing adolescence contribute to family farm productivity. Small and medium-size family farms are likely to rely on this labor, especially when adult family members work off the farm. The result may be unsupervised work by farm children.

Hazards

The family farm is a hazardous work environment. It is one of few hazardous workplaces where multiple generations of family members may live, work and play. A farm can be the source of many and differing life-threatening hazards. The most important indicator for safety and health is workload per worker-both physical labor and decision-making or mental workload. Many serious injuries happen to experienced farmers, working with familiar equipment in familiar fields, while doing tasks that they have been performing for years and even decades.

Hazardous agricultural materials including pesticides, fertilizers, flammable liquids, solvents and other cleaners are responsible for acute and chronic illnesses in farm workers and family members. Tractors, augers and other mechanized equipment have permitted a dramatic increase in the land and livestock that can be worked by a single farmer, but mechanization has contributed to severe injuries in agriculture. Machinery entanglement or tractor rollover, livestock, operating equipment on public roads, falling or being struck by falling objects, material handling, confined spaces and exposures to toxins, dust, moulds, gases, chemicals, vibration and noise are among the principal risks for illness and injury on farms. Climate and topography (e.g., weather, water, slopes, sinkholes and other obstacles) also contribute to the hazards.

Overall, agricultural occupations produce some of the highest rates of death and injury of all types of jobs. Unfortunately, farm children are at great risk along with their parents. As farm families attempt to remain profitable as they expand, family members may take on too high a workload and place themselves at greatly increased risk of fatigue, stress and injury. It is under these conditions that farm children are most likely to try to help out, often working unsupervised. In addition, unrelenting stressors associated with farming may lead to depression, family breakup and suicide. For example, principal owner-operators on single-family farms appear to be at particularly high risk for suicide when compared to other rural residents (Gunderson 1995). Further, the costs of illnesses and injuries are most often borne by the family member(s), and by the family enterprise-both as direct medical costs and in the reduction of labour necessary to maintain the operation.

Prevention

Classic agricultural safety and health programmes emphasize improved engineering design, education and good practices. Special attention on these farms needs to be placed on age-appropriate tasks for children and older adults. Young children should neither be allowed near operating farm equipment nor ever ride on tractors and other farm equipment. They should also be excluded from farmstead buildings that present hazards including electricity, confined spaces, chemical storage areas and operating equipment (National Committee for Childhood Agricultural Injury Prevention 1996). Warning labels should be maintained on equipment and chemicals so adults are informed of hazards and can thus better protect their families. The availability of experienced part-time or full-time workers reduces the burden on the family during periods of high workloads. The abilities of older adults should be a factor in the tasks that they perform.

Self-reliant farmers, determined to complete tasks regardless of the risks, may ignore safe work practices if they perceive them to interfere with farm productivity. Improving safety and health on family farms requires engaging the active participation of farmers and farm workers; improving attitudes, behavioral intentions and work practices; recognizing farm economics and productivity as powerful determinants in shaping the structure and organization of the enterprise; and including agricultural specialists, equipment dealers, insurance agents, bankers, local media, youth and other community members in generating and sustaining a broad climate of farm and community safety.

Ted Scharf, David E. Baker and Joyce Salg

PLANTATIONS

Melvin L. Myers and I.T. Cabrera*

*Adapted from 3rd edition, “Encyclopaedia of Occupational Health and Safety”.

The term plantation is widely used to describe large-scale units where industrial methods are applied to certain agricultural enterprises. These enterprises are found primarily in the tropical regions of Asia, Africa and Central and South America, but they are also found in certain subtropical areas where the climate and soil are suitable for the growth of tropical fruits and vegetation.

Plantation agriculture includes short-rotation crops, such as pineapple and sugar cane, as well as tree crops, such as bananas and rubber. In addition, the following tropical and subtropical crops are usually considered as plantation crops: tea, coffee, cocoa, coconuts, mango, sisal and palm nuts. However, large-scale cultivation of certain other crops, such as rice, tobacco, cotton, maize, citrus fruits, castor beans, peanuts, jute, hemp and bamboo, is also referred to as plantation cultivation. Plantation crops have several characteristics:

·     They are either tropical or subtropical products for which an export market exists.

·     Most require prompt initial processing.

·     The crop passes through few local marketing or processing centres before reaching the consumer.

·     They typically require a significant investment of fixed capital, such as processing facilities.

·     They generate some activity for most of the year, and thus offer continuous employment.

·     Monocropping is typical, which allows for specialization of technology and management.

While the cultivation of the various plantation crops requires widely different geographic, geological and climatic conditions, practically all of them thrive best in areas where climatic and environmental conditions are arduous. In addition, the extensive nature of plantation undertakings, and in most cases their isolation, has given rise to new settlements that differ considerably from indigenous settlements (NRC 1993).

Plantation Work

The main activity on a plantation is the cultivation of one of two kinds of crops. This involves the following kinds of work: soil preparation, planting, cultivation, weeding, crop treatment, harvesting, transportation and storage of produce. These operations entail the use of a variety of tools, machines and agricultural chemicals. Where virgin land is to be cultivated, it may be necessary to clear forest land by felling trees, uprooting stumps and burning off undergrowth, followed by ditch and irrigation channel digging. In addition to the basic cultivation work, other activities may also be carried out on a plantation: raising livestock, processing crops and maintaining and repairing buildings, plants, machinery, implements, roads and railway tracks. It may be necessary to generate electricity, dig wells, maintain irrigation trenches, operate engineering or woodworking shops and transport products to the market.

Child labour is employed on plantations around the world. Children work with their parents as part of a team for task-based compensation, or they are employed directly for special plantation jobs. They typically experience long and arduous working hours, little safety and health protection and inadequate diet, rest and education. Rather than direct employment, many children are recruited as labour through contractors, which is common for occasional and seasonal tasks. Employing labour through contracted intermediaries is a long-standing practice on plantations. The plantation management thus does not have an employer- employee relationship with the plantation workers. Rather, they contract with the intermediary to supply the labour. Generally, conditions of work for contract labour are inferior to those of directly employed workers.

Many plantation workers are paid based upon the tasks performed rather than the hours worked. For example, these tasks may include lines of sugar cane cut and loaded, number of rubber trees tapped, rows weeded, bushels of sisal cut, kilograms of tea plucked or hectares of fertilizer applied. Conditions such as climate and terrain may affect the time to complete these tasks, and whole families may work from dawn to dusk without taking a break. The majority of countries where plantation commodities are grown report that plantation employees work more than 40 hours per week. Moreover, most plantation workers move to their work location on foot, and since plantations are large, much time and effort are expended on travel to and from the job. This travel can take hours each way (ILO 1994).

Hazards and Their Prevention

Work on plantations involves numerous hazards relating to the work environment, the tools and equipment used and the very nature of the work. One of the first steps toward improving safety and health on plantations is to appoint a safety officer and form a joint safety and health committee. Safety officers should assure that buildings and equipment are kept safe and that work is performed safely. Safety committees bring management and labour together in a common undertaking and enable the workers to participate directly in improving safety. Safety committee functions include developing work rules for safety, participating in injury and disease investigations and identifying locations that place workers and their families in danger.

Medical services and first aid materials with adequate instruction should be provided. Medical doctors should be trained in the recognition of occupational diseases related to plantation work including pesticide poisoning and heat stress. A risk survey should be implemented on the plantation. The purpose of the survey is to comprehend risk circumstances so that preventive action can be taken. The safety and health committee can be engaged in the survey along with experts including the safety officer, the medical supervisor and inspectors. Table 64.2  shows the steps involved in a survey. The survey should result in action including the control of potential hazards as well as hazards that have resulted in an injury or disease (Partanen 1996). A description of some potential hazards and their control follow.

Table 64.2 Ten steps for a plantation work risk survey

1. Define the problem and its priority.

2. Find existing data.

3. Justify the need for more data.

4. Define survey objectives, design, population, time and methods.

5. Define tasks and costs, and their timing.

6. Prepare protocol.

7. Collect data.

8. Analyse data and assess risks.

9. Publish results.

10. Follow up.

Source: Partanen 1996.

Fatigue and climate-related hazards

The long hours and demanding work make fatigue a major concern. Fatigued workers may be unable to make safe judgements; this may lead to incidents that can result in injuries or other inadvertent exposures. Rest periods and shorter workdays can reduce fatigue.

Physical stress is increased by heat and relative humidity. Frequent water consumption and rest breaks help to avoid problems with heat stress.

Tool and equipment-related injuries

Poorly designed tools will often result in poor work posture, and poorly sharpened tools will require greater physical effort to complete tasks. Working in a bent or stooping position and lifting heavy loads imposes strain on the back. Working with arms above the shoulder can cause upper-extremity musculoskeletal disorders (figure 64.3). Proper tools should be selected to eliminate poor posture, and they should be well maintained. Heavy lifting can be reduced by lessening the weight of the load or engaging more workers to lift the load.

Figure 64.3 Banana cutters at work on "La Julia" plantation in Ecuador

Injuries can result from improper uses of hand tools such as machetes, scythes, axes and other sharp-edged or pointed tools, or portable power tools such as chain-saws; poor positioning and disrepair of ladders; or unsuitable replacements for broken ropes and chains. Workers should be trained in the proper use and maintenance of equipment and tools. Appropriate replacements should be provided for broken or damaged tools and equipment.

Unguarded machinery can entangle clothing or hair and can crush workers and result in serious injury or death. All machines should have safety built in, and the possibility of dangerous contact with moving parts should be eliminated. A lockout/tagout programme should be in effect for all maintenance and repair.

Machinery and equipment are also sources of excessive noise, resulting in hearing loss among plantation workers. Hearing protection should be used with machinery with high levels of noise. Low noise levels should be a factor in selecting equipment.

Vehicle-related injuries

Plantation roadways and paths may be narrow, thus presenting the hazard of head-on crashes between vehicles or overturns off the side of the road. Safe boarding of transport vehicles including trucks, tractor- or animal-drawn trailers and railways should be ensured. Where two-way roads are used, wider passages should be provided at suitable intervals to allow vehicles to pass. Adequate railing should be provided on bridges and along precipices and ravines.

Tractors and other vehicles pose two principal dangers to workers. One is tractor overturns, which commonly result in the fatal crushing of the operator. Employers should ensure that rollover protective structures are mounted on tractors. Seat-belts should also be worn during tractor operation. The other major problem is vehicle run-overs; workers should remain clear of vehicle travel paths, and extra riders should not be allowed on tractors unless safe seating is available.

Electricity

Electricity is used on plantations in shops and for processing crops and lighting buildings and grounds. Improper use of electric installations or equipment can expose workers to severe shocks, burns or electrocutions. The danger is more acute in damp places or when working with wet hands or clothing. Wherever water is present, or for electrical outlets outdoors, ground fault interrupter circuits should be installed. Wherever thunderstorms are frequent or severe, lightning protection should be provided for all plantation buildings, and workers should be trained in ways to minimize their danger of being struck and to locate safe refuges.

Fires

Electricity as well as open flames or smouldering cigarettes can provide the ignition source for fuel or organic dust explosions. Fuels—kerosene, gasoline or diesel fuel—can cause fires or explosions if mishandled or improperly stored. Greasy and combustible waste poses a risk of fire in shops. Fuels should be kept clear of any ignition source. Flameproof electrical devices and appliances should be used wherever flammables or explosives are present. Fuses or electrical breaker devices should also be used in electrical circuits.

Pesticides

The use of toxic agrochemicals is a major concern, particularly during the intensive use of pesticides, including herbicides, fungicides and insecticides. Exposures can take place during agricultural production, packaging, storage, transport, retailing, application (often by hand or aerial spraying), recycling or disposal. Risk of exposure to pesticides can be aggravated by illiteracy, poor or faulty labelling, leaking containers, poor or no protective gear, dangerous reformulations, ignorance of the hazard, disregard of rules and a lack of supervision or technical training. Workers applying pesticides should be trained in pesticide use and should wear appropriate clothing and respiratory protection, a particularly difficult behaviour to enforce in tropical areas where protective equipment can add to the heat stress of the wearer (figure 64.4). Alternatives to pesticide use should be a priority, or less toxic pesticides should be used.

Figure 64.4 Protective clothing worn when applying pesticides

Gerald F. Peedin

Animal-inflicted injuries and illnesses

On some plantations, draught animals are used for dragging or carrying loads. These animals include horses, donkeys, mules and oxen. These types of animals have injured workers by kicking or biting. They also potentially expose workers to zoonotic diseases including anthrax, brucellosis, rabies, Q-fever or tularaemia. Animals should be well trained, and those that exhibit dangerous behaviour should not be used for work. Bridles, harnesses, saddles and so on should be used and maintained in good condition and be properly adjusted. Diseased animals should be identified and treated or disposed of.

Poisonous snakes may be present on the ground or some species may fall from trees onto workers. Snakebite kits should be provided to workers and emergency procedures should be in place for obtaining medical assistance and the appropriate anti-venom drugs should be available. Special hats made of hard materials that are capable of deflecting snakes should be provided and worn in locations where snakes drop on their victims from trees.

Infectious diseases

Infectious diseases can be transmitted to plantation workers by rats that infest buildings, or by drinking water or food. Unsanitary water leads to dysentery, a common problem among plantation workers. Sanitary and washing facilities should be installed and maintained in accordance with national legislation, and safe drinking water consistent with national requirements should be provided to workers and their families.

Confined spaces

Confined spaces, such as silos, can pose problems of toxic gases or oxygen deficiency. Good ventilation of confined spaces should be assured prior to entry, or appropriate respiratory protective equipment should be worn.

MIGRANT AND SEASONAL FARMWORKERS

Marc B. Schenker

Migrant and seasonal farmworkers represent a large, global population with the double hazard of occupational health hazards of farming superimposed on a foundation of poverty and migrancy, with its associated health and safety problems. In the United States, for example, there are as many as 5 million migrant and seasonal farmworkers, although precise numbers are not known. As the total farm population has decreased in the United States, the proportion of hired farmworkers has increased. Globally, workers migrate in every region of the world for work, with movement generally from poorer to wealthier countries. In general, migrants are given more hazardous and difficult jobs and have increased rates of illness and injury. Poverty and lack of adequate legal protection exacerbate the risks of occupational and non-occupational disease.

Studies of hazardous exposures and health problems in this population have been limited because of the general paucity of occupational health studies in agriculture and the specific difficulties in studying farmworkers, due to their migratory residence patterns, language and cultural barriers, and limited economic and political resources.

Migrant and seasonal agricultural workers in the United States are predominantly young, Hispanic males, although farmworkers also include whites, blacks, Southeast Asians and other ethnic groups. Almost two-thirds are foreign born; most have low levels of education and do not speak or read English. Poverty is a hallmark of agricultural workers, with over half having family incomes below the poverty level. Substandard working conditions prevail, salaries are low and there are few benefits. For example, less than one-fourth have health insurance. Seasonal and migrant agricultural workers in the United States work about half the year on the farm. Most work is in labour-intensive crops such as harvesting of fruits, nuts or vegetables.

The general health status of agricultural workers directly derives from their working conditions and low income. Deficiencies exist in nutrition, housing, sanitation, education and access to medical care. Crowded living conditions and inadequate nutrition may also contribute to the increased risks of acute, infectious illnesses. Farmworkers see a physician less often than non-farmworking populations, and their visits are overwhelmingly for treatment of acute illnesses and injuries. Preventive care is deficient in farmworker populations, and surveys of farmworker communities find a high prevalence of individuals with medical problems requiring attention. Preventive services such as vision and dental care are seriously deficient, and other preventive services such as immunizations are below the population averages. Anaemia is common, probably reflecting poor nutritional status.

The poverty and other barriers for migrant and seasonal farmworkers generally result in substandard living and working conditions. Many workers still lack access to basic sanitary facilities at the worksite. Living conditions vary from adequate government-maintained housing to substandard shacks and camps used while work exists in a particular area. Poor sanitation and crowding may be particular problems, increasing the risks of infectious diseases in the population. These problems are exacerbated among workers who migrate to follow agricultural work, reducing community resources and interactions at each living site.

Various studies have shown a greater burden of infectious diseases on morbidity and mortality in this population. Parasitic diseases are significantly increased among migrant workers. Increased deaths have been found for tuberculosis, as well as many other chronic diseases such as those of the cardiovascular, respiratory and urinary tracts. The greatest increase in mortality rates is for traumatic injuries, similar to the increase seen for this cause among farmers.

The health status of children of farmworkers is of particular concern. In addition to the stresses of poverty, poor nutrition and poor living conditions, the relative deficiency of preventive health services has a particularly serious impact on children. They also are exposed to the hazards of farming at a young age, both by living in the farming environment and by doing agricultural work. Children under 5 years of age are most at risk of unintentional injury from agricultural hazards such as machinery and farm animals. Above 10 years of age, many children begin working, particularly at times of acute labour need such as during harvesting. Working children may not have the necessary physical strength and coordination for farm labour, nor do they have adequate judgement for many situations. Exposure to agrochemicals is a particular problem, since children may not be aware of recent field application or be able to read warnings on chemical containers.

Farmworkers are at increased risk of pesticide illness during work in the fields. Exposures most commonly occur from direct contact with the spray of application equipment, from prolonged contact with recently sprayed foliage or from drift of pesticide applied by aircraft or other spray equipment. Re-entry intervals exist in some countries to prevent foliar contact while the pesticide on foliage is still toxic, but many places have no re-entry intervals, or they may not be obeyed to hasten the harvest. Mass poisonings from pesticide exposure continue to occur among agricultural workers.

The greatest workplace hazard to farmworkers is from sprains, strains and traumatic injuries. The risk of these outcomes is increased by the repetitive nature of much labour-intensive agricultural work, which often involves workers bending or stooping to reach crops. Some harvesting tasks may require the worker to carry heavy bags full of the harvested commodity, often while balancing on a ladder. There is substantial risk of traumatic injuries and musculoskeletal strains in this situation.

In the United States, one of the most serious causes of fatal injuries to farmworkers is motor vehicle accidents. These often occur when farmworkers are driving or being driven to or from the fields very early or late in the day on unsafe rural roads. Collisions may also occur with slow-moving farm equipment.

Dust and chemical exposures result in an increased risk of respiratory symptoms and disease in farmworkers. The specific hazard will vary with the local conditions and commodities. For example, in dry-climate farming, inorganic dust exposure may result in chronic bronchitis and dust-borne diseases of the lung.

Skin disease is the most common work-related health problem among agricultural workers. There are numerous causes of skin disease in this population, including trauma from using hand equipment such as clippers, irritants and allergens in agrochemicals, allergenic plant and animal materials (including poison ivy and poison oak), nettles and other irritant plants, skin infections caused or exacerbated by heat or prolonged water contact, and sun exposure (which can cause skin cancer).

Many other chronic diseases may be more common among migrant and seasonal farmworkers, but data on actual risks are limited. These include cancer; adverse reproductive outcomes, including miscarriage, infertility and birth defects; and chronic neurologic disorders. All of these outcomes have been observed in other farming populations, or those with high-level exposure to various agricultural toxins, but little is known about actual risk in farmworkers.

URBAN AGRICULTURE

Melvin L. Myers

Agriculture conducted in urban areas is a major contributor to food, fuel and fibre production in the world, and it exists largely for the daily needs of consumers within cities and towns. Urban agriculture uses and reuses natural resources and urban wastes to produce crops and livestock. Table 64.3  summarizes the variety of farming systems in urban areas. Urban agriculture is a source of income for an estimated 100 million people, and a source of food for 500 million. It is oriented to urban markets rather than national or global markets, and it consists of many small-scale farms and some large-scale agribusinesses. Urban farmers range from a household garden in 20 m2 or less, to a small-scale farmer making a living on 200 m2, to a large-scale operator who may rent 10 hectares in an industrial zone (UNDP 1996).

Table 64.3 Farming systems in urban areas

Farming systems

Product

Location or technique

Aquaculture

Fish and seafood, frogs, vegetables, seaweed and fodder

Ponds, streams, cages, estuaries, sewage, lagoons, wetlands

Horticulture

Vegetables, fruit, herbs, beverages, compost

Homesites, parks, rights-of-way, containers, rooftops, hydroponics, wetlands, greenhouses, shallow bed techniques, layered horticulture

Floriculture

Flowers, insecticides, house plants

Ornamental horticulture, rooftops, containers, greenhouses, rights-of-way

Husbandry

Milk, eggs, meat, manure, hides, and fur

Zero-grazing, rights-of-way, hillsides, cooperatives, pens, open spaces

Agroforestry

Fuel, fruits and nuts, compost, building material

Street trees, homesites, steep slopes, vineyards, green belts, wetlands, orchards, forest parks, hedgerows

Mycoculture

Mushrooms, compost

Sheds, cellers

Vermaculture

Compost, worms for animal and fish feed

Sheds, trays

Sericulture

Silk

Homesites, trays

Apiculture

Honey, pollination, wax

Beehives, rights-of-way

Landscape gardening, arboriculture

Grounds design and upkeep, ornamentation, lawns, gardens

Yards, parks, play fields, commercial frontage, road sides, lawn and garden equipment

Beverage crops cultivation

Grapes (wine), hibiscus, palm tea, coffee, sugar cane, qat (tea substitute), matte (herbed tea), banana (beer)

Steep slopes, beverage processing

Sources: UNDP 1996; Rowntree 1987.

Landscaping, an offshoot of architecture, has emerged as another urban agriculture endeavour. Landscape gardening is the tending of plants for their ornamental appearance in public parks and gardens, private yards and gardens, and industrial and commercial building plantings. Landscape gardening includes lawn care, planting annuals (bedding plants), and planting and caring for perennials, shrubs and trees. Related to landscape gardening is grounds keeping, in which playing fields, golf courses, municipal parks and so on are tended (Franck and Brownstone 1987).

Process Overview

Urban agriculture is seen as a method for establishing ecological sustainability for towns and cities in the future. Urban agriculture usually engages shorter-cycle, higher-value market crops and uses multi-cropping and integrated farming techniques located where space and water are scarce. It uses both vertical and horizontal space to its best advantage. The principal feature of urban farming is the reuse of waste. The processes are typical of agriculture with similar inputs and steps, but the design is to use both human and animal wastes as fertilizer and water sources for growing vegetation. In this near idealized model, external inputs still exist, however, such as pesticides (UNDP 1996).

In the special case of landscaping, appearance is the product. The care of lawns and ornamental trees, shrubs and flowers are the focus of the landscape operation. In general, the landscaper purchases planting stock from a nursery or a turf farm, plants the stock and cares for it routinely and frequently. It typically is labour and chemical intensive, and the use of hand and power tools and lawn and garden equipment is also common. Grass mowing is a routine chore in landscaping.

Hazards and Their Control

Urban agriculture is typically small scale, close to housing, exposed to urban pollutants, engaged in the reuse of waste and exposed to potential theft of products and related violence. The hazards related to various types of agriculture, pesticides and composting discussed elsewhere in this volume are similar (UNDP 1996).

In the developed countries, suburban farms and landscaping enterprises make use of lawn and garden equipment. This equipment includes small tractors (tractor attachments such as mowers, front-end loaders and blades) and utility haulers (similar to all-terrain vehicles). Other tractor attachments include tillers, carts, snow blowers and trimmers. These tractors all have engines, use fuel, have moving parts, carry an operator and are often used with towed or mounted equipment. They are substantially smaller than the typical agricultural tractor, but they can be overturned and cause serious injury. The fuel used on these tractors poses a fire hazard (Deere & Co. 1994).

Many of the tractor attachments have their own peculiar hazards. Children riding with adults have fallen from the tractor and been crushed under the wheels or chopped by mower blades. Mowers pose two types of hazards: one is potential contact with rotating blades and the other is being struck by objects thrown from the blades. Both front-end loaders and blades are operated hydraulically, and if left unattended and elevated, pose a hazard of falling onto anyone who gets a body part under the attachment. Utility haulers are inexpensive when compared to the cost of a small truck. They can turn over on steep terrain, especially when turning. They are dangerous when used on public roads because of the possibility of collision. (See table 64.4  for several safety tips for operating some types of lawn and garden equipment.)

Table 64.4 Safety advice for using mechanical lawn and garden equipment

Tractors (smaller than regular farm equipment)

Prevent rollovers:

  • Do not drive where the tractor can tip or slip; avoid steep slopes; watch for rocks, holes and similar hazards.
  • Travel up and down slopes or hillsides; avoid travelling across steep slopes.
  • Slow down and use care in turning to prevent tipping or losing steering and braking control.
  • Stay within the tractor load limits; use ballast for stability; refer to the operator’s manual.

Never allow extra riders.

Maintain safety interlocks; they ensure that powered equipment is disengaged  when the operator is not seated or when starting the tractor.

Rotary lawn mowers (tractor mounted or walk-behind type)

Maintain safety interlocks.

Use proper blades and guards.

Keep all safety blades and guards in place and in good condition.

Wear substantial closed-toe shoes to prevent slipping and protect against injury.

Do not allow anyone to put their hands or feet near the mower deck or discharge chute  while the machine is running; stop the mower if children are nearby.

When leaving the machine, shut it down.

To prevent thrown object injuries:

  • Clear the area to be mowed.
  • Keep the mower deck guards, discharge chute, or bag in place.
  • Stop the mower whenever someone comes near.

When working on mower (on push or walk-behind type mowers), disconnect the spark plug  to prevent engine starting.

Avoid fires by not spilling fuel on hot surfaces nor handling fuel near sparks or flames;  avoid the accumulation of fuel, oil and trash around hot surfaces.

Front-end loaders (attached to lawn and garden tractors)

Avoid overloading.

Back down ramps and steep inclines with the loader bucket lowered.

Watch the driving route rather than watching the bucket.

Operate the hydraulic loader controls only from the tractor seat.

Use the loader only for materials that it was designed to handle.

Lower the bucket to the ground when leaving the machine.

Utility haulers (similar to all-terrain vehicles but designed for off-the-road work)

Avoid rollovers:

  • Practise driving on smooth terrain before driving on rough terrain.
  • Do not speed; slow down before turning (especially on slopes).
  • Reduce speed on slopes and rough terrain.
  • Watch for holes, rocks and other hidden hazards.

Never allow extra riders.

Avoid tipping over by distributing the cargo box load so it is not too high or too far to rear.

Avoid an upset when raising the cargo box by staying clear of the edge of loading docks  or embankments.

When towing loads, place weight in the cargo box to assure traction.

Avoid driving on public roads.

Children should not operate these machines.

A helmet is recommended head protection.

Source: Adapted from Deere & Co. 1994.

GREENHOUSE AND NURSERY OPERATIONS

Mark M. Methner and John A. Miles

The nursery industry raises plants for the replanting market (see figure 64.5). Hardy plants are grown outside, and the less hardy plants are propagated and raised inside, typically in greenhouses, to protect them from cold temperatures or too much solar radiation or wind. Many plants grown inside during harsh growing conditions are grown outside in favourable weather conditions. Typical nursery crops are trees and shrubs, and the typical greenhouse crops include flowers, vegetables and herbs. The nursery industry grows plants for the replanting market, but greenhouses are also used for growing crops for seasonal markets, such as tomatoes during the freezing months of winter.

Figure 64.5 Setting coffee plants in a nursery in Côte d’Ivoire

The plant nursery industry constitutes a large and growing sector of agriculture. In California, where there are more than 3,000 commercial nursery operations, nursery crops are a high value-per-acre commodity, ranking fifth in state farm income. As with much of western US agriculture, the employee population is dominated by workers from Mexico or other Central American countries. The majority of these workers are not migrant, but are settled in local communities with their families (Mines and Martin 1986). Most speak Spanish only or as a primary language and have little or no formal education. Wages are low for most jobs, and there is a labour surplus. Similar situations exist throughout the world.

Nursery work is considered a comparatively good job by most agricultural workers because it is year-round, comparatively well-paid and frequently includes workers’ compensation insurance and employee health benefits. Few workers belong to labour organizations in this industry, and most workers are employed directly by the enterprise rather than by farm labour contractors.

Greenhouses provide a controlled environment for plants and are used for a variety of purposes, which include growing rare and exotic plants, protecting producing plants (such as flowers, tomatoes and peppers) from winter weather and starting seedlings. The controlled environment within a greenhouse is advantageous to those who wish to grow crops year-round, regardless of seasonal conditions outdoors. Greenhouse operations have expanded in temperate climates. For example, in the Ukraine, the total area of greenhouses has grown from 3,070 hectares (ha) in 1985 to 3,200 ha in 1990 to an estimated 3,400 ha in 1995 (Viten, Krashyyuh and Ilyna 1994).

The gable (equal sloping roof) greenhouse is typical. It provides good exposure to winter sunlight, drainage and wind protection. The framing materials for greenhouses include wood, aluminium or a combination of steel pipe and wood. Side walls or siding can be made from a variety of materials including plywood, aluminium, wood or vinyl. In the Ukraine, 60% of the greenhouses have masonry block walls. Covers include glass or plastic, and in some parts of the world, the glass-covered house is called a glasshouse. The plastic can be either rigid or a flexible film. Rigid plastics used as covers include fibreglass, acrylic and polycarbonate. Flexible plastic covers include polyethylene, polyvinyl chloride and polyester. Polycarbonate, which withstands breakage from thrown objects, and the flexible plastics require frequent replacement. Covers can vary from clear to opaque, and they serve three purposes. One is to let sunlight in for the plants. Another is for heating within an enclosure. The last is protecting the plants from environmental stress, including snow, rain, hail, high winds, birds, small animals and insects.

The greenhouse operation requires the control of temperature, humidity and ventilation, using artificial heat sources, exhaust and inlet fans, shading (such as with movable slats or netting), cooling equipment (such as wet-pad or evaporative cooling), humidification and climate-control equipment (Jones 1978).

Nursery and greenhouse workers are exposed to a variety of hazards, including skin irritants, dust, noise, heat stress, musculoskeletal disorders (sprains and strains), pesticides and injuries related to vehicles, machines, slips and falls and electricity. The hazards discussed below are limited to ergonomic hazards in nursery work and pesticide hazards in greenhouse work. Many of these hazards are common for the two operations.

Nursery Operations

Typical operations at a large wholesale nursery specializing in container-grown outdoor bedding and ornamental plants consist of four stages:

1.     Propagation stage. New plants are started in a specialized medium using one of four standard methods: cuttings from mature plants, tissue culture, seeds and grafting.

2.     Replanting stage. As plants grow they are replanted into individual plastic containers called “cans” (typically 2 or 3 times during the early growth cycle). A powered conveyor carries the new, larger cans past a hopper where they are filled with soil. As the cans continue down the conveyor, plants are manually transplanted into them, and finally they are manually transferred onto a trailer for transport to the field.

3.     Growing stage or field operations. Plants are held in outdoor groups until fully mature. During this period, tasks include watering, pruning, fertilizing and weeding, tying-staking-shaping and spacing as plants grow.

4.     Shipping. Mature plants are removed to the shipping area, labelled, organized by order load, and loaded into trucks. This operation can also include truck unloading at retail sites.

Ergonomic hazards

Nursery work, as with other agricultural commodities, has a pattern of high rates of sprain and strain injuries. AgSafe data (1992) suggest that 38.9% of all reported injuries in horticultural specialties (including nurseries) were sprains and strains, slightly above the proportion for agriculture as a whole. Overexertion as a cause of injury for this area was cited for 30.2% of reported injuries, also above the proportion for the industry as a whole.

The most common risk factors for the development of work-related musculoskeletal problems have been identified as occurring in the following job tasks:

During propagation, the worker stands or sits at a work table, empties a basket of plant cuttings, and uses hand shears to cut them into smaller pieces. The shears are held in the dominant hand; plant material is grasped with the other hand. After each piece of plant material is cut, the shears must be disinfected by dipping them in a solution in a small container in the work bench.

When cutting, one hand is engaged in very repetitive gripping, with an average of 50 to 60 cuts per minute. Mild to moderate wrist flexion and ulnar deviation occur throughout the cutting cycle. The other hand is used to hold the cuttings, orient them for cutting, and discard the remains in a bin. Moderate wrist extension and ulnar deviation occur throughout this cycle also.

Workers in this specialized job are highly skilled and work virtually full-time year-round without rotation into other jobs. Workers report pain and numbness in the hand, wrist and arm. After a period of years on this job, they demonstrate an elevated incidence of carpal tunnel syndrome.

In transporting plants from a conveyor belt to a trailer, the worker grasps 3 or 4 3.8-litre containers in each hand and places them on a trailer located either to one side of or behind him or her. This job cycle is repeated 13 to 20 times per minute. Risk factors include highly repetitive gripping, high pinch forces and awkward postures, including trunk, lumbar and shoulder flexion.

In transporting plants from a trailer to a planting bed, the worker grasps 3 or 4 3.8-l containers in each hand, carries them up to 17 m, and places them on the ground along a predetermined row. This job cycle is repeated 3 to 5 times per minute. Handling cans is a nearly full-time, year-round job for many workers. It is associated with pain in the fingers and hands, upper extremities and lower back. Because field workers tend to be younger, the predicted high rate of chronic back injury is not documented at this time.

The pruner works with various shears to snip unwanted or dead parts off the tops and sides of plants. The worker is usually standing or bent over to reach plants. The dominant hand holds the shears and is engaged in very repetitive gripping, with an average of 40 to 50 cuts per minute. The fingers of the same hand are also used to pinch off small twigs or other plant parts. The nondominant hand grasps the can for a rapid pick and place, and also holds the cuttings in a static grip with a moderate wrist flexion and ulnar deviation present throughout the cutting cycle. Because pruning is a part-time task for most field workers, some relief and recovery are achieved due to task variation. However, it is associated with pain in the fingers and hand, wrist, upper extremities and lower back.

To allow plants adequate room to grow and expand, spacing must be done periodically. This entails grasping and lifting 3 to 4 plants in each hand, carrying them a short distance, and placing them on the ground in rows. This cycle is repeated 3 to 5 times per minute. Like pruning, spacing is a part-time task for most field workers, allowing opportunity for relief and recovery. It is also associated with pain in fingers and hands, wrists, upper extremities and lower back.

Most nursery jobs are human-energy intensive, and this, coupled with the repetitive nature of many tasks, leads to substantial risk of repetitive-motion injuries. Tools to assist the workers by improving body posture and reducing the energy requirements of particular tasks have just begun to be developed.

Greenhouse Operations

Typical operations in a greenhouse vary depending on whether the purpose is to grow rare and exotic plants, production plants or seedlings. The growing of rare or exotic plants is a year-round enterprise. Production plants are typically grown within the greenhouse to protect them from the weather; thus, greenhouses can be used seasonally. The growth of seedlings is similar to nursery operations, but the market is plants for spring replanting after the last freeze. The tasks involved in greenhouse growing include putting the soil into small containers, planting the seed in each of the containers, watering and fertilizing the plants, trimming or thinning the plants as needed (see figure 64.6), applying fumigants or pesticides and transporting the plants or product from the greenhouse. Soil filling and planting has become a mechanized operation in the production greenhouse. The composition of the potting soil may be a mix of peat, perlite and vermiculite. Trimming may be mechanized, depending upon the crop. Watering may be directly with a hose or through an automated sprinkler or piping system. Nutrients are added to the water to fertilize the plants. Application of pesticides by hand sprayer is typical. Soil sterilization is done either by steam or chemicals, including dibromochloropropane (DBCP). The transport of plants or product is typically a manual exercise.

Figure 64.6 Clipping (mowing) tobacco transplants in a greenhouse in North Carolina

This is done with a conventional lawn mower attached to the sprayer boom,  which is also used to apply water and pesticides when needed.

Gerald F. Peedin

Pesticides Used in Greenhouses

Diseases and insects that attack plants can result in major problems for greenhouse operators. Often, preventing such damage is easier than trying to eradicate the pests afterward. Some common pests that inflict the most damage on greenhouse crops are insects, fungi, viruses, bacteria and nematodes. To combat these undesirable organisms, special chemicals (pesticides) are applied to the plants to kill the pests.

There are many ways of applying pesticides so that they are effective. The most common application methods are: liquid sprays, mists, dusts, fogs, smokes, aerosol canisters and granules. Pesticide sprays involve the use of a water/pesticide mixture contained in a tank that has a hose with a spray nozzle attached to it. Under pressure, the mixture is directed onto the plants as liquid droplets. Mists are generated by a technique similar to the spray technique, but the resulting droplets are smaller. Pesticide dusts are often released into the air and allowed to settle onto the plant surface. Foggers use heating devices to generate very small droplets directed at the plants. Pesticide smokes are generated by igniting a sparkler and placing it in a canister that contains the chemical.

Aerosol canisters are pressurized metal containers that release the pesticide to the air when a valve is opened. Finally, granular pesticides are placed on top of the soil and then watered. The watering dissolves the granules and transports the chemical to the roots of the plant, where it can either kill organisms in the soil or be absorbed by the plant and kill organisms that feed on it.

With each different method of application of a pesticide comes the hazard of being exposed to the chemical. The two most common routes of exposure are through the skin (dermal) and through the lungs (respiratory). Another, but less common, route of exposure is by ingesting food or drinks contaminated with pesticides. Greenhouse workers who handle the chemicals or the treated plants may be poisoned if proper safety precautions are not followed.

Ways to avoid poisoning include proper use of greenhouse ventilation systems, using and maintaining the appropriate PPE (suits, gloves, respirators, boots—see figure 64.7), observing recommended re-entry times and following the pesticide label instructions. Some additional safety precautions are: storage of all pesticides inside a locked, well-ventilated area; posting signs in areas where plants have been treated; and comprehensive pesticide training that includes proper application and handling techniques. Finally, all pesticide applicators should be trained in appropriate disposal techniques for old pesticides and empty pesticide containers.

Figure 64.7 Worker in full protective gear applies pesticides in a greenhouse

S. Henao

FLORICULTURE

Samuel H. Henao

Since the early 1990s, in many countries and across several continents, floriculture as an economic activity has been expanding rapidly. Its growing importance in export markets has resulted in an integrated development of several aspects of this field of activity, including production, technology, scientific research, transportation and conservation.

Production

The production of cut flowers has two essential components:

1.     the process of production, which involves all activities directly related to the generation and the development of the product up to the moment of packing

2.     the various activities that aid in the production and promote the marketing and distribution of cut flowers.

The production process itself can be divided into three basic parts: germination, cultivation and post-harvest procedures.

Germination is carried out by planting parent plants from which cuttings are obtained for cultivation.

The cuttings of different flowers are planted on beds of a rooting medium. The beds are made from steam-treated dross and treated with chemical products to disinfect the growing medium and to facilitate root development.

Cultivation is done in greenhouses which house the beds of rooting medium where the flowers are planted and grown as discussed in the article "Greenhouse and nursery operations" in this chapter and as shown in figure 64.8. Cultivation includes preparing the soil, planting the cuttings (figure 64.9) and harvesting the flowers.

Figure 64.8 Tending flowers in a greenhouse

Figure 64.9 Planting cuttings in a greenhouse

Planting includes the cycle that begins with placing the cuttings in the rooting medium and ends with the flowering plant. It includes the following activities: planting, normal irrigation, drip irrigation with fertilizer, cultivation and weeding of the soil, pinching the tip of the plants to force branching and obtain more flowers, preparing the props that hold the plants upright, and the growth, branching and flowering of the plant.

Production concludes with the gathering of the flowers and their separation by classification.

At the post-harvest stage—in addition to selection and classification—the flowers are covered with plastic hoods, a sanitary treatment is applied, and they are packed for shipment.

Secondary activities include monitoring the health of the plants to detect pests and to diagnose plant illnesses early, obtaining raw materials from the warehouse, and maintaining the furnaces.

Health Risk Factors

The most important risk factors in each of the different areas of work are:

·     chemical substances

·     extreme temperatures—heat

·     non-ionizing radiation

·     infectious disease

·     ergonomic factors

·     mechanical factors

·     psychosocial factors.

Chemical substances

Intoxication and chronic illness due to pesticides

The levels of morbidity/mortality found in workers due to exposure to pesticides are not the consequence of a simple relation between the chemical agent and the person who has suffered exposure to it, but also reflect the interplay of many other factors. Among these are the length of exposure, individual susceptibility, the nutritional state of the person exposed, educational and cultural variables and the socioeconomic conditions under which the workers live.

In addition to the active ingredients of pesticides, the substances that convey the active ingredients and the additives should also be taken into consideration, because sometimes those substances can have adverse effects that are more harmful than those of the active ingredients.

The toxicity of pesticides made with organophosphates is due to their effect on the central nervous system, because they inhibit the activity of the enzyme acetylcholinesterase. The effects are cumulative, and delayed effects have also been noted on the central and the peripheral nervous systems. According to studies carried out in several countries, the prevalence of inhibition of this enzyme among workers who handle these pesticides fluctuates between 3 and 18%.

The long-term effects are pathological processes that develop after a latency period and are due to repeated exposures. Among the long-term effects known to be due to pesticide exposure are skin lesions, nerve damage and mutagenic effects.

Respiratory problems

Decorative plants can irritate the respiratory system and cause coughing and sneezing. In addition, plant scents or odours may exacerbate symptoms of asthma or allergic rhinitis, although they have not been shown to cause allergies. Pollen from the chrysanthemum and the sunflower can cause asthma. Dust from dried plants sometimes causes allergies.

Dermatitis

The cases of occupational dermatitis found in floriculture are about 90% primarily due to contact dermatitis. Of these, about 60% are caused by primary irritants and 40% are due to allergic reactions. The acute form is characterized by reddening (erythema), swelling (oedema), pimples (papules), vesicles or blisters. It is especially localized on the hands, wrists and forearms. The chronic form can have deep fissures, lichenification (thickening and hardening) of the skin, and severe xerosis (dryness). It can be incapacitating and even irreversible.

Floriculture is one of those activities where contact with primary irritants or allergenic substances is high, and for that reason it is important to promote and use preventive measures, such as gloves.

Extreme temperatures—heat

When work must be carried out in a hot environment, as in the case of hothouses, the thermal load on the worker is the sum of the heat of the work environment plus the energy expended on the task itself.

Physical effects of excessive exposure to heat include heat rash, cramps and muscle spasms, exhaustion and fainting spells. Heat rash, in addition to being uncomfortable, lowers the worker’s tolerance to heat. If perspiration is abundant and liquids and electrolytes are not replenished adequately, cramps and muscle spasms can set in. Heat exhaustion occurs when vasomotor control and cardiac output are insufficient to compensate for the additional demands placed on these systems by the heat stress. Fainting spells represent a very serious clinical situation that can lead to confusion, delirium and coma.

Precautions include frequent rest breaks in cool areas, availability of beverages to drink, rotating of tasks requiring heavy exertion and wearing of light-coloured clothing.

Non-ionizing radiation

The most important kinds of non-ionizing radiation that floriculture workers are exposed to are ultraviolet (UV) radiation, visible light and infrared radiation. The most serious effects of UV radiation are solar erythema, actinic dermatitis, irritative conjunctivitis and photokeratitis.

Radiation from the visible spectrum of light may cause retinal and macular degeneration. One symptom of exposure to infrared radiation is superficial burn of the cornea, and prolonged exposure can lead to the premature appearance of cataracts.

Precautions include keeping the skin covered, wearing tinted glasses, and medical surveillance.

Ergonomic factors

Workers who maintain a static body posture for long periods of time (see figure 64.10) can suffer from resulting static muscle contractions and from alterations of the peripheral, vascular and nervous systems. Repetitive movements are more common in tasks that require manual dexterity. For example, clipping shears can require a lot of force and involve repetitive motion. The most frequently observed effects are musculoskeletal impairments, including tendinitis of the elbow and wrist, carpal tunnel syndrome and impairment of movement at the shoulder.

Figure 64.10 Bending over for extended periods is a common cause of ergonomic problems

Job rotation and the proper ergonomic design of equipment such as clipping shears are needed precautions. Redesigning the workplace to require less bending is another solution.

Infectious diseases

Floriculture may expose workers to a variety of biological agents. Early signs of an infection are rarely specific, although they are generally well-defined enough to lead to a suspicion of illness. The signs, symptomatology and precautions depend on the agent, which includes tetanus, rabies, hepatitis and so on. Preventive measures include a source of potable water, good sanitary facilities, first aid and medical care for cuts and abrasions.

Other factors

The most common health and safety hazards associated with mechanical factors are cuts, abrasions and single and multiple traumas, which most frequently injure the hands and face. Such injuries must be attended to immediately. Workers should have up-to-date tetanus shots and adequate first-aid facilities must be available.

The psychosocial environment can also endanger worker health. The results of exposure to these factors can have the following consequences: physiological changes (indigestion, constipation, palpitations, difficulty breathing, hyperventilation, insomnia and anxiety); psychological disturbances (tension and depression); and behavioural disturbances (absenteeism, instability, dissatisfaction).

FARMWORKER EDUCATION ABOUT PESTICIDES: A CASE STUDY

Merri Weinger

At the San Antonio farm, several workers became poisoned when applying the pesticide Lannate. An investigation of the case revealed that the workers had been using backpack sprayers for application without wearing any protective clothing, gloves or boots. Their employer had never provided the necessary equipment, and soap and showers were also unavailable. Following the poisonings, the employer was directed to take the appropriate corrective actions.

When the Ministry of Health made a follow-up inspection, they discovered that many farmers were still not using any protective clothing or equipment. When they were asked why, some said that the equipment was too hot and uncomfortable. Others explained that they had been working this way for years and never had any problems. Several commented that they didn’t need the equipment because they drank a large glass of milk after applying pesticides.

This experience, which took place in Nicaragua, is common to many parts of the world and illustrates the challenge to effective farmworker training. Training must be accompanied by provision of a safe work environment and legislative enforcement, but must also consider the barriers to implementing safe work practices and incorporate them in training programmes. These barriers, such as unsafe work environments, absence of protective equipment and attitudes and beliefs which are not health-promoting, should be directly discussed in training sessions, and strategies to address them should be developed.

This article describes an action-oriented training approach applied in two multidisciplinary pesticide projects that were designed to address the problem of farmworker pesticide poisoning. They were implemented in Nicaragua by CARE, Nicaragua and the American Friends Service Committee (1985 to 1989) and in the Central American region by the International Labour Organization (ILO, 1993 to present). In addition to a strong educational approach, the Nicaraguan project developed improved methods to mix and load pesticides, a medical monitoring plan to screen workers for overexposure to pesticides and a system to collect data for epidemiological investigation (Weinger and Lyons 1992). Within its multifaceted project, the ILO emphasized legislative improvements, training and building a regional network of pesticide educators.

Key elements of both projects were the implementation of a training needs assessment in order to tailor teaching content to the target audience, the use of a variety of participatory teaching approaches (Weinger and Wallerstein 1990) and the production of a teacher’s guide and educational materials to facilitate the learning process. Training topics included the health effects of pesticides, symptoms of pesticide poisoning, rights, resources and a problem-solving component which analysed the obstacles to working safely and how to resolve them.

Although there were many similarities between the two projects, the Nicaraguan project emphasized worker education while the regional project focused on teacher training. This article provides selected guidelines for both worker and teacher training.

Worker Education

Needs assessment

The first step in developing the training programme was the needs assessment or “listening phase”, which identified problems and obstacles to effective change, recognized factors which were conducive to change, defined values and beliefs held by the farmworkers and identified specific hazardous exposures and experiences which needed to be incorporated into the training. Walkthrough inspections were used by the Nicaraguan project team to observe work practices and sources of worker exposure to pesticides. Photographs were taken of the work environment and work practices for documentation, analysis and discussion during the training. The team also listened for emotional issues which might be barriers to action: worker frustration with inadequate personal protection, lack of soap and water or lack of safe alternatives to currently used pesticides.

Training methods and objectives

The next step in the training process was to identify the content areas to be covered utilizing information gained from listening to workers and then to select appropriate training methods based on the learning objectives. The training had four objectives: providing information; identifying and changing attitudes/emotions; promoting healthy behaviours; and developing action/problem-solving skills. What follows are examples of methods grouped under the objective which they best achieve. The following methods were incorporated into a 2-day training session (Wallerstein and Weinger 1992).

Methods for information objectives

Flipchart. In Nicaragua, the project staff needed visual educational tools which were easily portable and independent of electricity for use during field training or with medical screening on the farms. The flipchart included 18 drawings based on real-life situations, which were designed for use as discussion starters. Each picture had specific objectives and key questions that were outlined in an accompanying guide for instructors.

The flipchart could be used both to provide information and to promote problem analysis leading to action planning. For example, a drawing was used to provide information on the routes of entry by asking “How do pesticides enter the body?” To generate analysis of the problem of pesticide poisoning, the instructor would ask participants: “What’s happening here? Is this scene familiar? Why does this occur? What can (he) you do about it?” The introduction of two or more people into a drawing (of two people entering a recently sprayed field) encourages discussion of suspected motivations and feelings. “Why is she reading the sign? Why did he go right in?” With effective visual images, the same picture may trigger a variety of discussions, depending upon the group.

Slides. Slides which portray familiar images or problems were used in the same way as the flipchart. Using photos taken during the needs assessment phase, a slide show was created following the path of pesticide use from selection and purchase to disposal and clean-up at the end of the workday.

Methods for attitude-emotion objectives

Attitudes and emotions may effectively block learning and influence how health and safety practices are implemented back on the job.

Scripted role-play. A scripted role-play was often used to explore attitudes and trigger discussion of the problems of exposure to pesticides. The following script was given to three workers, who read their roles to the entire group.

Jose: What’s the matter?

Rafael: I’m about ready to give up. Two workers were poisoned today, just one week after that big training session. Nothing ever changes around here.

Jose: What did you expect? The managers didn’t even attend the training.

Sara: But at least they scheduled a training for the workers. That’s more than the other farms are doing.

Jose: Setting up a training is one thing, but what about follow-up? Are the managers providing showers and adequate protective equipment?

Sara: Have you ever thought that the workers might have something to do with these poisonings? How do you know they’re working safely?

Rafael: I don’t know. All I know is that two guys are in the hospital today and I have to go back to work.

The role-play was developed to explore the complex problem of pesticide health and safety and the multiple elements involved in resolving it, including training. In the discussion which followed, the facilitator asked the group if they shared any of the attitudes expressed by the farmworkers in the role-play, explored obstacles to resolving the problems portrayed and solicited strategies for overcoming them.

Worksheet questionnaire. In addition to serving as an excellent discussion starter and providing factual information, a questionnaire can also be a vehicle for eliciting attitudes. Sample questions for a farmworker group in Nicaragua were:

1.     Drinking milk before work is effective in preventing pesticide poisoning.

     Agree     Disagree

2.     All pesticides have the same effect on your health.

     Agree     Disagree

A discussion of attitudes was encouraged by inviting participants with conflicting viewpoints to present and justify their opinions. Rather than affirming the “correct” answer, the instructor acknowledged useful elements in the variety of attitudes that were expressed.

Methods for behavioural skill objectives

Behavioural skills are the desired competencies that workers will acquire as a result of training. The most effective way to achieve objectives for behavioural skill development is to provide participants with opportunities to practise in the class, to see an activity and perform it.

Personal protective equipment demonstration. A display of protective equipment and clothing was laid out on a table in front of the class, including an array of appropriate and inappropriate options. The trainer asked a volunteer from the audience to get dressed for work applying pesticides. The farmworker chose clothing from the display and put it on; the audience was asked to comment. A discussion followed concerning appropriate protective clothing and alternatives to uncomfortable clothing.

Hands-on practice. Both trainers and farmworkers in Nicaragua learned to interpret pesticide labels by reading them in small groups during the class. In this activity, the class was divided into groups and given the task of reading different labels as a group. For low-literacy groups, volunteer participants were recruited to read the label aloud and lead their group through a worksheet questionnaire on the label, which emphasized visual cues to determine level of toxicity. Back in the large group, volunteer spokespeople introduced their pesticide to the group with instructions for potential users.

Methods for action/problem-solving objectives

A primary goal of the training session is to provide farmworkers with the information and skills to make changes back on the job.

Discussion starters. A discussion starter can be used to pose problems or potential obstacles to change, for analysis by the group. A discussion starter can take a variety of forms: a role-play, a picture in a flipchart or slide, a case study. To lead a dialogue on the discussion starter, there is a 5-step questioning process which invites participants to identify the problem, project themselves into the situation being presented, share their personal reactions, analyse the causes of the problem and suggest action strategies (Weinger and Wallerstein 1990).

Case studies. Cases were drawn from real and familiar situations that occurred in Nicaragua that were identified in the planning process. They most commonly illustrated problems such as employer noncompliance, worker noncompliance with safety precautions within their control and the dilemma of a worker with symptoms that may be related to pesticide exposure. A sample case study was used to introduce this article.

Participants read the case in small groups and responded to a series of questions such as: What are some of the causes of pesticide poisoning in this incident? Who’s benefiting? Who’s being harmed? What steps would you take to prevent a similar problem in the future?

Action planning. Prior to the conclusion of the training session, participants worked independently or in groups to develop a plan of action to increase workplace health and safety when pesticides are used. Using a worksheet, participants identified at least one step they could take to promote safe working conditions and practices.

Evaluation and Teacher Training

Determining the extent to which the sessions met their objectives is a crucial part of training projects. Evaluation tools included a written post-workshop questionnaire and follow-up visits to farms as well as surveys and interviews with participants 6 months following the training session.

Training teachers who would utilize the approach outlined above to provide information and training to farmworkers was an essential component of the ILO-sponsored Central American programmes. The objectives of the teacher training programme were to increase the knowledge on pesticide health and safety and the teaching skill of trainers; to increase the number and quality of training sessions directed toward farmworkers, employers, extension workers and agronomists in project countries; and to initiate a network of educators in pesticide health and safety in the region.

Training topics in the 1-week session included: an overview of the health effects of pesticides, safe work practices and equipment; the principles of adult education; steps in planning an educational programme and how to implement them; demonstration of selected teaching methods; overview of presentation skills; practice teaching by participants using participatory methods, with critique; and development of action plans for future teaching about pesticides and alternatives to their use. A 2-week session allows time to conduct a field visit and training needs assessment during the workshop, to develop educational materials in the classroom and to conduct worker training sessions in the field.

A trainer’s guide and sample curricula were provided during the workshop to facilitate practice teaching both in the classroom and following the workshop. The educators’ network offers another source of support and a vehicle for sharing innovative teaching approaches and materials.

Conclusion

The success of this teaching approach with workers in the cotton fields of Nicaragua, trade unionists in Panama and trainers from the Ministry of Health in Costa Rica, among others, demonstrates its adaptability to a variety of work settings and target groups. Its goals are not only to increase knowledge and skills, but also to provide the tools for problem-solving in the field after the teaching sessions have ended. One must be clear, however, that education alone cannot resolve the problems of pesticide use and abuse. A multidisciplinary approach which includes farmworker organizing, legislative enforcement strategies, engineering controls, medical monitoring and investigation into alternatives to pesticides is essential to effect comprehensive changes in pesticide practices.

PLANTING AND GROWING OPERATIONS

Yuri Kundiev and V.I. Chernyuk

Modern agriculture is based on highly efficient equipment, especially high-speed, powerful tractors and agricultural machines. Tractors with mounted and trailed implements allow the mechanization of many agricultural operations.

Use of tractors allows farmers to accomplish the main tillage and care of plants in the optimum time without major manual labour. Permanent enlargement of farms, extension of land under cultivation and intensification of crop rotation promotes more efficient agriculture as well. Widespread use of high-speed assemblies is hampered by two factors: existing agricultural methods based mainly on machines and implements with passive tools; and difficulties in ensuring safe working conditions for the high-speed tractor assembly operator.

Mechanization can accomplish approximately 70% of planting and growing operations. It is used at all stages of crop cultivation and harvesting as well. Nevertheless, each stage of planting and growing has its own requisite set of machines, tools and environmental conditions, and this variability of the production and environmental factors has an influence upon the tractor driver.

Cultivation of the Land

Cultivation of the land (ploughing, harrowing, scuffing, disk harrowing, entire cultivation, rolling-down) is important and the most labour-intensive preliminary stage of crop production. These operations involve 30% of planting and growing operations.

As a rule, loosening of the soil results in the formation of dust. The nature of the dust in the air is variable, and depends on meteorological conditions, season, kind of work, type of soil and so on. Dust concentration in tractor cabs can vary from a few mg/m3 to hundreds of mg/m3, depending essentially on the cab enclosure. Approximately 60 to 65% of cases exceed the permissible total dust concentration level; permissible levels of respirable (less than or equal to 5 microns) dust are exceeded 60 to 80% of the time (see figure 64.11). Silica content in the dust varies from 0.5 to 20% (Kundiev 1983).

Figure 64.11 Tractor driver exposures to dust during land cultivation

Cultivation consists of power-consuming operations, especially during ploughing, and it demands a considerable mobilization of the power resources of machines, generating considerable levels of noise where tractor drivers sit. These noise levels amount to 86 to 90 dBA and higher, creating a considerable risk of hearing disorders for these workers.

As a rule, whole-body vibration levels where the tractor driver is seated can be very high, exceeding levels established by the International Organization for Standardization (ISO 1985) for fatigue-decreased proficiency boundary and frequently for exposure limit.

Ground preparation is conducted mainly in early spring and autumn, so the microclimate of cabs in temperate zones for machines without air conditioners is not a health problem except on occasional hot days.

Sowing and Growing

Ensuring that sowing attachments or ploughing implements move in a straight line and that tractors follow marker tracks or the middle of the row are characteristic features of the sowing and care of crops.

In general, these activities require the driver to work in uncomfortable positions and involve considerable nervous and emotional tension due to restricted working-zone visibility, resulting in rapid development of operator fatigue.

The layout of sowing machines and their preparation for use, as well as the necessity of manual auxiliary work, especially materials handling, may involve considerable physical loads.

A wide geographical distribution of grain varieties results in a diversity of meteorological conditions when sowing. Winter crop sowing for different climate zones can be performed, for example, when the outdoor temperature ranges from 3–10 °C to 30–35 °C. Spring crop sowings are performed when the outdoor temperature ranges from 0 °C to 15–20 °C. The temperatures in tractor cabs without air conditioners can be very high in regions where climate is mild and hot.

Microclimate conditions in tractor cabs are favourable as a rule during tilled crops sowing (sugar beet, maize, sunflower) in temperate zones. Cultivation of crops is performed when the outdoor temperature is high and solar radiation is intense. The air temperature in cabs without microclimate control can rise to 40 °C and more. Tractor drivers can work under uncomfortable conditions about 40 to 70% of the total time involved in the care of crops.

Working operations for tilled crops cultivation involve considerable moving of earth, causing formation of dust. Maximum ground dust concentrations in the breathing zone air do not exceed 10 to 20 mg/m3. The dust is 90% inorganic, containing a large amount of free silica. Noise and vibration levels where the driver sits are a little lower than those existing during cultivation.

During sowing and cultivation, workers can be exposed to manures, chemical fertilizers and pesticides. When safety regulations for handling these materials are not followed, and if machines are not working properly, the breathing zone concentration of hazardous materials can exceed permissible values.

Harvesting

As a rule, harvesting lasts from 25 to 40 days. Dust, microclimate conditions and noise can be hazards during harvesting.

Breathing zone dust concentrations depend chiefly on outside concentration and the airtightness of the harvesting machine’s cab. Older machines without cabs leave drivers exposed to the dust. Dust formation is most intensive during the harvesting of dry corn, when the dust concentration at non-enclosed combines’ cabs can be as much as 60 to 90 mg/m3. Dust consists mainly of plant scraps, pollen and mushroom spores, mostly in large, nonrespirable particles (larger than 10 microns). Free silica content is less than 5.5%.

Formation of dust during sugar beet harvesting is lower. Maximum dust concentration at the cab does not exceed 30 mg/m3.

Harvesting of grain is generally performed in the hottest season. Temperature in the cab can rise to 36 to 40 °C. The flux level of direct solar radiation is 500 W/m2 and more when ordinary glass is used for cab windows. Tinted glass lowers the temperature of air in the cab by 1 to 1.6 °C. A mechanical forced ventilation system with a flow rate of 350 m3/h can create a temperature difference between inside and outside air of 5 to 7 °C. If the combine is equipped with adjustable louvers, this difference drops to 4 to 6 °C.

Tilled crops are harvested in the autumn months. As a rule conditions of the microclimate in cabs in this time are not a great health problem.

Experience in developed countries points to the fact that agriculture at small farms can be profitable with the use of small-scale mechanization (minitractors—motorized units with a capacity of up to 18 horsepower, with different kinds of auxiliary equipment).

Use of such equipment gives rise to a number of specific health problems. These problems include: intensification of workload in certain seasons, the use of child labour and the labour of elderly persons, absence of the means of protection against intensive noise, whole-body and local vibration, harmful meteorological conditions, dust, pesticides, and exhaust gases. The effort necessary to move the control levers of motorized units can amount to 60 to 80 N (newtons).

Some kinds of work are performed with the help of draught animals or done manually due to insufficient equipment or because of the impossibility of using machinery for some reason. Manual labour demands as a rule considerable physical effort. Power requirements during ploughing, horse-drawn sowing and manual mowing can amount to 5,000 to 6,000 cal/day and more.

Injuries are common during manual work, especially among inexperienced workers, and cases of plant burns, insect and reptile stings and dermatitis from the sap of some plants are frequent.

Prevention

One of the main trends in tractor construction is the improvement of working conditions of tractor operators. Side by side with perfection of the design of protective cabs is the search for ways of coordinating technical parameters of various tractor units with the functional abilities of operators. The aim of this research consists of ensuring the effectiveness of control and driving functions as well as necessary ergonomic parameters of the workplace environment.

Effectiveness of control and driving of tractor assemblies is ensured by good visibility of the working zone, by optimizing assemblies and control panel design and by proper ergonomic design of tractor seats.

Common ways of increasing visibility are increasing the viewing area of the cab using panoramic glass, improved layout of auxiliary equipment (e.g., fuel tank), rationalization of seat location, use of rear view mirrors and so on.

Optimization of construction control elements is connected with the construction of the control mechanism’s drive. Along with hydraulic and electric drives, a new improvement is suspended control pedals. This allows improved access and increased driving comfort. Functional coding (by means of form, colour and/or symbolic signs) plays an important part in recognition of the control elements.

Rational layout of instrumentation (which comprises 15 to 20 units in modern tractors) requires taking into account further increases in indicators due to remote control of technological process conditions, automation of the driving and operating of the technological equipment.

The operator’s seat is designed to guarantee a comfortable position and effective driving of the machine and tractor assembly. Design of modern tractor seats takes into account anthropometric data of the human body. Seats have adjustable back and arms and can be adjusted according to the operator’s size, in both horizontal and vertical dimensions (figure 64.12).

Figure 64.12 Angle parameters of optimal work posture of a tractor driver

Precautions against harmful working conditions for tractor drivers include means of protection against noise and vibration, microclimate normalization and airtight sealing of cabs.

Besides special engineering of the engine to reduce noise at its source, considerable effect is achieved by mounting the engine on vibration isolators, isolating the cab from the tractor body with the help of shock absorbers and a number of measures designed for absorption of noise in the cab. Flaky, sound-absorbing lagging with a decorative surface is applied for this purpose to cab wall panels, and rugs made of rubber and porolon are laid on the cab floor. Hard perforated panelling with an air gap of 30 to 50 mm is applied to the ceiling. These measures have reduced noise levels in cabs to 80–83 dBA.

The main means of damping low-frequency vibration in the cab is use of an effective seat suspension. Nevertheless, the effect of whole-body vibration damping achieved this way does not exceed 20 to 30%.

Agricultural ground levelling gives considerable opportunities for decreasing vibration.

Improvement of the microclimate conditions in tractor cabs is reached with the help of both standard equipment (e.g., fans with filter elements, thermo-insulating tinted glass, sun-proof cap peaks, adjustable louvers) and special devices (e.g., air conditioners). Modern tractor heating systems are designed as an autonomous assembly attached to the engine’s cooling system and using warmed water to heat the air. Combined air conditioners and air heaters are also available.

Complex solutions of the problem of noise, vibration and heat isolation and sealing of cabs can be reached with the help of sealed cab capsules designed with suspended control pedals and wire rope systems of drives.

Ease of access to tractor engines and assemblies for their maintenance and repairs, as well as obtaining timely information about technical condition of certain units of the assembly, are important indices of the level of tractor operator working conditions. Eliminating the cab bonnet, forward inclination of the cab, detachable panels of the engine’s bonnet and so on are available in certain types of tractors.

In the future, tractor cabs are likely to be equipped with automatic control units, with television screens for observation of implements that are out of the operator’s field of vision and with units for conditioning of microclimate. Cabs will be mounted on outside rotary rods so they can be moved to a required position.

Rational organization of work and rest is of great importance for the prevention of fatigue and diseases of agricultural workers. In the hot season, daily routine ought to provide for working mainly in the morning and evening hours, reserving the hottest time for rest. During exhausting work (moving, hoeing), short regular breaks are necessary. Special attention has to be devoted to the rational, balanced nourishment of workers with due regard for the energy requirements of the tasks. Drinking regularly during the heat is of great importance. As a rule, workers drink traditional beverages (tea, coffee, fruit juices, infusions, broths and so on) in addition to water. Availability of sufficient amounts of wholesome liquids of high quality is very important.

Availability of comfortable overalls and personal protection equipment (PPE) (respirators, hearing protectors), especially during contact with dust and chemicals, is very important as well.

Medical control of the agricultural workers’ health has to be oriented to prevention of common occupational diseases, such as infectious diseases, chemical exposures, injuries, ergonomic problems and so forth. Teaching safe working methods, information about matters of hygiene and sanitation are of great importance.

HARVESTING OPERATIONS

William E. Field

The gathering in of agricultural crops upon maturity, or the practice of harvesting, signals the end of the production cycle prior to storage and processing. The size and quality of the crop removed from the field, orchard or vineyard represents the most significant measure of a farmer’s productivity and success. The value that has been placed on the outcome of the harvest is reflected in the terms used almost universally to measure and compare agricultural productivity, such as kilograms per hectare (kg/ha), bales per hectare, bushels per acre (bu/a) and tons per acre or hectare. From an agronomic perspective, it is actually the inputs that determine the yield; however, it is the harvest that becomes the primary determinant of whether or not there will be sufficient seed and resources to ensure the sustainability of the farm and those it supports. Because of the significance of harvest and all of its related activities, this part of the agricultural cycle has taken on an almost spiritual role in the lives of farmers throughout the world.

Few agricultural practices illustrate more clearly the scope and diversity of technology- and work-related hazards found in agricultural production than harvesting. Crop harvesting is carried out under a wide variety of conditions, over various types of terrain, utilizing machines from simple to complex that must handle a diversity of crops; it involves considerable physical effort from the farmer (Snyder and Bobick 1995). For these reasons, any attempt to briefly generalize the characteristics or nature of harvest practices and harvest-related hazards is extremely difficult. Small grains (rice, wheat, barley, oats and so on), for example, which dominate much of the planted cropland in the world, represent not only some of the most highly mechanized crops, but in large regions of Africa and Asia are harvested in a manner that would be familiar to farmers 2,500 years ago. The use of hand sickles to harvest a few stalks at a time, hard-packed clay threshing floors and simple threshing devices remain the primary tools of harvest for far too many producers.

The primary hazards associated with the more labour-intensive harvesting practices have changed little with time and are often overshadowed by the perceived increased risks associated with greater mechanization. Long hours of exposure to the elements, the physical demands resulting from lifting heavy loads, repetitive motion and awkward or stooped posture, along with natural hazards such as poisonous insects and snakes, have historically taken, and continue to take, a significant toll (see figure 64.13). Harvesting grain or sugar cane with a sickle or machete, picking fruit or vegetables by hand and manually removing peanuts from the vine are dirty, uncomfortable and exhausting tasks that in many communities frequently are completed by large numbers of children and women. One of the strongest motivating forces that has shaped modern harvesting practices has been the desire to remove the physical drudgery associated with manual harvesting.

Figure 64.13 Hand-harvesting millet

Even if the resources were available to mechanize harvesting and reduce its risks (and for many small farmers in many areas of the world, they are not), investments to improve the safety and health aspects of harvesting would likely have smaller returns than would comparable investments to improve housing, water quality or health care. This is especially true if farmers have access to large numbers of unemployed or underemployed workers. High levels of unemployment and limited job opportunities, for example, place large numbers of younger workers at risk of injury during harvest because they are cheaper to use than machines. Even in many countries with highly mechanized agricultural practices, child labour laws frequently exempt children involved in agricultural activities. For example, special provisions of the US Department of Labor child labour laws continue to exempt children under 16 during harvest and allow them to operate agricultural equipment under certain conditions (DOL 1968).

Contrary to a general perception that greater mechanization in agriculture has increased the risks associated with agricultural production, with respect to harvesting, nothing could be further from the truth. Through the introduction of intensive mechanization in major grain- and forage-producing regions, the amount of time required to produce a bushel of grain, for example, has dropped from over an hour to under a minute (Griffin 1973). This accomplishment, though heavily dependent upon fossil fuels, has released tens of millions of people from the drudgery and unsafe working conditions associated with hand harvesting. Mechanization has resulted in not only tremendous increases in productivity and yields, but also the near elimination of the most historically significant harvest-related injuries, such as those involving livestock.

The intensive mechanization of the harvesting process, however, has introduced new hazards, which have required periods of adjustment and in some cases the replacement of machines with improved practices and designs that were either more productive or less hazardous. An example of this technological evolution was experienced with the transition that took place in corn harvesting in North America between the 1930s and 1970s. Up through the 1930s, the corn crop was almost entirely harvested by hand and transported to on-farm storage sites by horse-drawn wagons. The primary cause of harvest-related injuries was related to working with horses (NSC 1942). With the introduction and widespread use of the mechanical, tractor-drawn corn picker in the 1940s, horse- and livestock-related deaths and injuries rapidly declined during the harvest period, and there was a corresponding growth in the number of corn picker-related injuries. This was not because corn pickers were inherently more dangerous, but because the injuries reflected a rapid transition to a new practice that had not been fully refined and that farmers were unfamiliar with. As farmers adjusted to the technology and manufacturers improved the performance of the corn picker, and as more uniform varieties of corn were planted that were better suited to machine harvesting, the number of deaths and injuries quickly declined. In other words, the introduction of the corn picker ultimately resulted in a decline in harvest- related injuries due to exposure to traditional hazards.

With the introduction in the 1960s of the self-propelled combine, which could harvest higher-yielding corn varieties at rates ten or more times faster than the corn picker, corn picker injuries almost disappeared. But, once again, as with the corn picker, the combine introduced a new set of hazards that required a period of adjustment. For example, the ability to gather, cut, separate and clean the grain in the field using one machine changed the handling of grain from a lumpy flow process in the form of ear corn to shelled corn, which was almost fluid-like. Consequently, in the 1970s, there was a dramatic increase in the number of auger-related injuries, and of engulfments and suffocations in flowing grain that took place in storage structures and grain transport vehicles (Kelley 1996). In addition, there were new categories of injuries being reported that were related to the sheer size and weight of the combine, such as falls from the operator platform and ladders, which can place the operator as much as 4 m off the ground, and operators being crushed beneath the multi-row gathering unit.

The mechanization of the corn harvest directly contributed to one of the most dramatic shifts in rural population ever experienced in North America. The farm population, in less than 75 years after the introduction of hybrid varieties of corn and the mechanical corn picker, went from over 50% to less than 5% of the total population. Through this period of increased productivity and greatly reduced labour demands, the overall exposure to agricultural workplace hazards was substantially reduced, contributing to a drop in reported farm-related deaths from over 14,000 in 1942 to fewer than 900 in 1995 (NSC 1995).

Injuries associated with modern harvesting operations typically relate to tractors, machinery, grain-handling equipment and grain-storage structures. Since the 1950s, tractors have contributed to approximately one-half of all farm-related fatalities, with overturns being the single most important contributing factor. The utilization of rollover protective structures (ROPS) has proven to be the single most important intervention strategy in reducing the number of tractor-related fatalities (Deere & Co. 1994). Other design features that improved the safety and health of tractor operators included wider wheel bases and designs that lowered the centre of gravity to improve stability, all-weather operator enclosures to reduce exposure to the elements and dust, ergonomically designed seating and controls and reduced noise levels.

The problem of tractor-related injuries, however, remains significant and is a growing concern in areas that are being rapidly mechanized, such as China and India. In many areas of the world it is more likely to see the tractor being used as a vehicle of highway transport or a stationary power source than being used in the field to produce crops, as it was designed to do. In these areas, tractors are typically introduced with minimal operator training and are used widely as a means of transporting multiple passengers, another use for which the tractor was not designed. The result has been that runovers of extra riders who have fallen from the tractors during operation has become the second leading cause of tractor-related fatalities. If the trend towards greater utilization of ROPS continues, runovers may eventually become the leading cause of tractor-related fatalities worldwide.

Though used fewer hours during the year than tractors, harvesting equipment such as combines are involved in about twice as many injuries per 1,000 machines (Etherton et al. 1991). These injuries often take place during servicing, repairing or adjusting the machine when the power to machine components is still engaged (NSC 1986). Recent design changes have been made to incorporate more passive and active operator warnings and interlocks, such as safety switches in the operator seat to prevent machine operation when no one is in the seat, and to reduce the number of maintenance points to reduce operator exposure to operating machinery. Many of these design concepts, however, remain voluntary, are frequently by-passed by the operator and are not universally found on all harvesting machines.

Hay and forage harvesting equipment exposes workers to hazards similar to those found on combines. This equipment contains components that cut, crush, grind, chop and blow crop material at high speed, leaving little room for human error. As with grain harvesting, hay and forage harvesting must take place in a timely fashion in order to prevent damage to the crop from the elements. This added stress to complete tasks rapidly, in conjunction with machine hazards, frequently leads to injuries (Murphy and Williams 1983).

Traditionally, the hay baler has been identified as a frequent source of serious injuries. These machines are used under some of the most harsh conditions found in any type of harvesting. High temperature, rough terrain, dusty conditions and the need for frequent adjustments contribute to a high rate of injury. The conversion to large packages or bales of hay and mechanical handling systems has improved safety with a few exceptions, as was the case with the introduction of the early designs of the round baler. The aggressive compression rolls on the front of these machines resulted in a large number of hand and arm amputations. This design was later replaced with a less aggressive gathering unit, which nearly eliminated the problem.

Fire is a potential problem for many types of harvesting operations. Crops that are required to be dried to less than 15% moisture content for proper storage make excellent fuel if ignited. Combines and cotton harvesters are especially vulnerable to fires during field operation. Design features such as the use of diesel engines and protected electrical systems, proper equipment maintenance and operator access to fire extinguishers have been shown to reduce the risk of fire-related damage or injury (Shutske et al. 1991).

Noise and dust are two other hazards that are typically intrinsic to harvesting operations. Both pose serious long-term health risks to the operator of harvesting equipment. The inclusion of environmentally controlled operator enclosures in the design of modern harvesting equipment has done much to reduce operator exposure to excessive noise pressures and dust levels. However, most farmers have yet to benefit from this safety feature. The use of PPE such as ear plugs and disposable dust masks provides an alternative, but less effective, means of protection from these hazards.

As harvesting operations around the world become increasingly mechanized, there will be a continuing shift from environmental-, animal- and hand tool-related injuries to those caused by machines. Drawing upon the experiences of farmers and manufacturers of harvesting equipment who have completed this transition should prove useful in reducing the adjustment period and preventing injuries caused by lack of familiarity and poor design. The experience of farmers with even the most highly mechanized harvesting operations, however, suggests that the injury problem will not be totally eliminated. Contributions of operator error and machine design will continue to play a significant role in injury causation. But there is no question that in addition to greater productivity, the process of mechanization has significantly reduced the risks associated with harvesting.

STORING AND TRANSPORTATION OPERATIONS

Thomas L. Bean

Storing

The growing and gathering of crops and production of livestock has long been recognized as one of the world’s oldest and most important occupations. Farming and ranching today is as diverse as the many crops, fibres and livestock which are produced. At one extreme, the farming unit may consist of a single family that cultivates the soil and plants and harvests the crop, all by hand over a limited area. The opposite extreme includes large corporate farms spanning vast areas that are highly mechanized, using sophisticated machinery, equipment and facilities. The same is true for the storage of food and fibre. Storage of agricultural products may be as rudimentary as simple huts and hand-dug pits, and as complex as towering silos, bunkers, bins and refrigerated units.

Hazards and their prevention

Agricultural products such as grains, hays, fruit, nuts, vegetables and plant fibre are often stored for later human and livestock consumption or sale to the general populace or to manufacturers. The storage of agricultural products prior to shipment to market may occur in a variety of structures—pits, bunkers, bins, silos, refrigerated units, carts, wagons, barns and railroad cars, to mention a few. Despite the diversity of products being stored and of storage facilities, there are hazards which are common to the storage process:

Falls and falling objects

Falls may occur from heights or at the same level. In the case of bins, silos, barns and other storage structures, falls from heights most often occur from and in storage structures. Most often the cause is unguarded roofs, floor openings, stairways, lofts and shafts, and climbing ladders or standing on raised work areas such as an unprotected platform. Falls from height may also result from climbing on or off the transportation unit (e.g., wagons, carts and tractors). Falls from the same level occur from slippery surfaces, tripping over objects or being pushed by a moving object. Protection against falls includes such measures as:

·     provision of safety belts, harnesses, lifelines and safety boots

·     installation of guard rails, toeboards, cat-ladders or crawling boards on sloped roofs

·     guarded floor openings, lofts and shafts

·     use of the standard rise and run of stairways, provision of handrails on both sides, and application non-skid strips where necessary

·     maintaining floors in good condition, free from uneven surfaces, holes and accumulations of waste or slippery substances

·     provision of handholds on permanent ladders, guard platforms and landings

·     maintaining extension or step ladders in good condition and training employees on their use.

Agricultural products may be stored loose in a facility or bundled, bagged, crated or bailed. Loose storage is often associated with grains such as wheat, corn or soybeans. Bundled, bagged, crated or bailed products include hay, straw, vegetables, grains and feeds. Falls of materials occur in all types of storage. Collapse of unsecured stacked foodstuffs, overhead materials and piles of goods are often causes of injury. Employees should be trained in the correct stacking of goods to prevent their collapse. Employers and managers must monitor the workplace for compliance.

Confined spaces

Agricultural products may be stored in two types of facilities—those that contain enough oxygen to sustain life, such as barns, open carts and wagons, and those that do not, such as some silos, tanks and refrigeration units. The latter are confined spaces, and should be treated with appropriate precautions. The oxygen level should be monitored prior to entry and a supplied air or self-contained breathing unit used if necessary; someone else should be on hand. Suffocation may also occur in either type of facility if the goods which it contains have the characteristics of a fluid. This is commonly associated with grains and similar foodstuffs. The worker dies as a result of drowning. In grain bins it is a common practice for an agricultural worker to enter the bin due to difficulties in loading or unloading, often caused by a condition of the grain resulting in bridging. Workers attempting to alleviate the situation by unbridging the grain may voluntarily walk on the bridged grain. They may fall in and be covered with the grain or be sucked under if the loading or unloading equipment is operational. Bridging also may occur to the sides of such structures, in which case a worker may enter to knock down the material sticking to the sides and become engulfed when the material fails. A lockout/tagout system and fall protection such as a safety belt and rope are essential if workers are to enter this type of structure. Children’s safety is of special concern. Often inquisitive, playful and wanting to do adult chores, they are attracted to such structures, and the results are all-too-often fatal.

Fruit and vegetables are often kept in cold storage prior to shipping to market. As indicated in the above paragraph, depending on the type of unit, cold storage may be considered a confined space and should be monitored for oxygen content. Other hazards include frostbite and cold-induced injury or death from body temperature loss following prolonged exposure to cold. Personal protective clothing should be worn appropriate to the temperature within the cold-storage unit.

Gases and poisons

Depending on the moisture content of the product when it is placed in storage and atmospheric and other conditions, feeds, grains and fibres may produce dangerous gases. Such gases include carbon monoxide (CO), carbon dioxide (CO2) and oxides of nitrogen (NOx), some of which may cause death in a matter of minutes. This is also especially important if the goods are stored in a facility in which nonlethal gases may be allowed to accumulate to dangerous levels, displacing oxygen. If the potential for gas production exists, then monitoring for gases should be done. In addition, foods and feeds may have been sprayed or treated with a pesticide during the growing period to kill weeds, insects or disease, or during the storage process to reduce spoilage or mould, spore or insect damage. This may add to the hazards of gas production, inhalation of dusts and handling of the product. Special care should be taken by workers to wear PPE depending on the nature and longevity of the treatment, the product used and the label directions.

Machine hazards

Storage facilities may contain a variety of machinery for conveying the product. These range from belt and roller conveyors to blowers, augers, slides and other such product-handling devices, each with its own power source. Hazards and suitable precautions include:

·     Nip points formed by belts, pulleys and gears. Agricultural workers should be protected from nip and shear points by an appropriate guarding around the point of potential contact.

·     Protruding belt fasteners, setscrews, keys, bolts and grooves. Protruding setscrews, keys or bolts on revolving shafts should be countersunk, encased or shrouded. Belt fasteners should be inspected and repaired.

·     Shear points caused by flywheel arms, augers and their housing, pulley spokes, crank and lever mechanisms. These should be guarded or enclosed.

·     Contact with moving transmission or electrical elements. These should be guarded or enclosed.

·     Inadvertent starting of machinery or equipment. A system for locking out or tagging out equipment prior to maintenance or repair should be implemented and enforced.

·     Loose clothing or hair getting wound on or caught by shafts. Clothing that is loose, frayed or that has hanging threads should never be worn. Other personal protective apparel and shoes appropriate to the job task should be worn.

·     Excessive noise. Noise exposure should be monitored and administrative, engineering and/or personal protective controls should be taken if necessary.

Employees should be trained and aware of the hazards, basic safety rules and safe working methods.

Health outcomes

Agricultural workers who are involved in the handling of agricultural products for storage are at risk for respiratory disorders. Exposures to a variety of dusts, gases, chemicals, silica, fungal spores and endotoxins can result in damage to the lungs. Recent studies link lung disorders caused by these substances to workers who handle grain, cotton, flax, hemp, hay and tobacco. Therefore the populations at risk are worldwide. Agricultural lung disorders have many common names, some of which include: occupational asthma, farmer’s lung, green tobacco sickness, brown lung, organic dust toxic syndrome, silo filler’s or unloader’s disease, bronchitis and airway obstruction. Symptoms may first manifest themselves as being characteristic of influenza (chills, fever, coughing, headaches, myalgias and breathing difficulty). This is especially true for organic dusts. Prevention of lung dysfunction should include an assessment of the worker’s environment, health promotion programmes targeted at primary prevention and the use of personal protective respirators and other protective devices based on the environmental assessment.

Transportation Operations

Although it may seem simple, the transportation of goods to market is often as complex and hazardous as growing and storing the crop. The transportation of products to market is as diversified as the types of farming operations. Transportation may range from goods being carried by humans and livestock, to being transported by simple mechanical devices such as bicycles and animal-drawn carts, being hauled by complex mechanical equipment such as large carts and wagons pulled by tractors, to the use of commercial transportation systems, which include large trucks, buses, trains and airplanes. As the world’s population increases and urban areas grow, road travel of agricultural equipment and implements of husbandry has increased. In the US, according to the National Safety Council (NSC), 8,000 farm tractors and other agricultural vehicles were involved in highway accidents in 1992 (NSC 1993). Many farming operations are consolidating and expanding by acquiring or renting a number of smaller farms which are typically scattered and not adjoining. A 1991 study in Ohio showed that 79% of the farms surveyed operated in multiple locations (Bean and Lawrence 1992).

Hazards and their prevention

Although each of the modes of transportation mentioned above will have its own unique hazards, it is the intermix of civilian traffic with agricultural transport machinery and equipment that is of major concern. The increase in road travel of agricultural equipment has resulted in a greater number of collisions between motor vehicles and slower moving agricultural equipment. Farm equipment and implements of husbandry may be wider than the width of the road. Due to pressure of planting at the right time to assure a crop or harvesting and getting the crop to a market or storage location as quickly as possible, agricultural machinery must often travel on the roadways during periods of darkness, early morning or evening.

An in-depth study of all 50 states’ codes in the United States revealed that the lighting and marking requirements vary greatly from state to state. This diversity in requirements does not communicate a consistent message to motor vehicle drivers (Eicher 1993). Faster speeds of other vehicles combined with inadequate lighting or marking of agricultural equipment is often a deadly combination. A recent study in the United States found that the common accident types are rear end, sideswipe-meeting, sideswipe-passing, angle, head-on, backing and other. In 20% of the 803 two-vehicle crashes studied, the farm vehicle was struck from an angle. In 28% of the crashes, the farm vehicle was sideswiped (15% meeting and 13% passing). Twenty-two per cent of the accidents consisted of rear-end (15%), head-on (4%) and backing (3%) collisions. The remaining 25% were crashes which were caused by something other than a moving vehicle (i.e., a parked vehicle, pedestrian, animal and so on) (Glascock et al. 1993).

Livestock are used in many parts of the world as the “horsepower” to transport agricultural products. Although beasts of burden are generally reliable, most are colourblind, have territorial and maternal instincts, react independently and unexpectedly, and are of great strength. Such animals have caused vehicle crashes. Falls from agricultural machinery and implements of husbandry are common.

The following general safety principles apply to transportation operations:

·     Local traffic rules, regulations or laws should be learned and obeyed.

·     No riders or passengers other than those that are necessary to accomplish the transport and unloading duties should be permitted.

·     Vehicles should stay as close to the shoulder of the road as road conditions will allow.

·     Passing other vehicles (moving or parked) and pedestrians must be done with caution.

·     Broken-down vehicles should be moved off the road if possible.

·     All marking and lighting on machinery and equipment should be maintained and clean.

·     Driving should never be done under the influence of alcohol or drugs.

Laws and regulations may dictate the state of acceptable lighting and marking. However, many such regulations only describe the minimal acceptable standards. Unless such regulations specifically prohibit retrofitting and adding additional lighting and marking, farmers should consider adding such devices. It is important that such lighting and marking devices be installed not only on self-propelled implements but also on pieces of equipment that they may be pulling or trailing.

Lights are especially critical for dusk, dawn and night-time movement of agricultural equipment. If the agricultural vehicle has a power source, consideration should be given to having, at a minimum: two headlights, two tail-lights, two turn signals and two brake lights.

Tail-lights, turn signals and brake lights may be incorporated into single units or can be attached as separate entities. Standards for such devices may be found through standard-setting organizations such as the American Society of Agricultural Engineers (ASAE), the American National Standards Institute (ANSI), the European Committee for Standardization (CEN) and the International Organization for Standardization (ISO).

If the agricultural vehicle does not have a power source, battery-powered lights, although not as effective, may be used. Many such lights are commercially available in a variety of types (flood, blinking, rotating and strobe) and sizes. If it is impossible to obtain these devices, then reflectors, flags and other alternative materials discussed below may be used.

Many new retroreflective fluorescent materials are available today to aid in marking agricultural vehicles for enhanced visibility. They are manufactured in patches or strips in a variety of colours. Local regulations should be consulted for acceptable colours or colour combinations.

Fluorescent materials provide excellent daytime visibility by relying on solar radiation for their light-emitting properties. A complex photochemical reaction takes place when the fluorescent pigments absorb non-visible solar radiation and re-emit the energy as a longer wavelength of light. In a sense, fluorescent materials appear to “glow” in the daytime and appear brighter than the conventional colours in the same light conditions. The primary disadvantage of fluorescent materials is their deterioration with prolonged exposure to solar radiation.

Reflection is an element of sight. Wavelengths of light strike an object and are either absorbed or bounced back in all directions (diffused reflection) or at an angle exactly opposite to the angle at which the light struck the object (specular reflection). Retroreflectivity is very similar to specular reflection; however, the light is reflected directly back toward the light source. There are three primary forms of retroreflective materials, each having a different degree of retroreflectivity based on how they were manufactured. They are presented here in increasing order of retroreflectivity: enclosed lens (often called engineering grade or Type ID), encapsulated lens (high intensity) and cube corner (diamond grade, prismatic, DOT C2 or Type IIIB). These retroreflective materials are excellent for night-time visual identification. These materials are also of great assistance in defining the extremities of agricultural implements. In this application, strips of retroreflective and fluorescent material across the width of the machinery, front and back, best communicate to drivers of other, nonagricultural vehicles the actual width of the equipment.

The distinctive red triangle with a yellow-orange centre is used in the United States, Canada and many other parts of the world to designate a class of vehicles as “slow moving”. This means the vehicle travels less than 40 km per hour on the roadway. Typically, other vehicles travel much faster, and the difference in speed may result in a misjudgement on the part of the faster vehicle driver, affecting the driver’s ability to stop in time to avoid an accident. This emblem or an acceptable substitute should always be used.

Health outcomes

Agricultural workers who are involved in the transportation of agricultural products may be at risk for respiratory disorders. Exposures to a variety of dusts, chemicals, silica, fungal spores and endotoxins may result in damage to the lungs. This is somewhat dependent on whether the transport vehicle has an enclosed cab and whether the operator engages in the loading and unloading process. If the transport vehicle has been used in the process of pesticide application, pesticides could be present and trapped inside the cab unless it has an air filtration system. Nevertheless, symptoms may first manifest themselves as being characteristic of influenza. This is especially true for organic dusts. Prevention of lung dysfunction should include an assessment of the worker’s environment, health promotion programmes targeted at primary prevention and the use of personal protective masks, respirators and other protective devices.

MANUAL OPERATIONS IN FARMING

Pranab Kumar Nag

Agricultural methods and practices vary across national boundaries:

·     industrial agriculture—industrialized countries of the West (temperate climate) and specialized sectors of the tropical countries

·     green revolution agriculture—well endowed areas in the tropics, primarily irrigated plains and deltas of Asia, Latin America and North Africa

·     resource-poor agriculture—hinterlands, dry lands, forests, mountains and hills, near deserts and swamps. About 1 billion people in Asia, 300 million in sub-Saharan Africa and 100 million in Latin America are dependent on this form of agriculture. Women comprise a large proportion of subsistence farmers—nearly 80% of the food for sub-Saharan Africa, 50 to 60% of Asia’s food, 46% of the Caribbean’s food, 31% of North Africa and the Middle East’s food and 30% of Latin America’s food is produced by women (Dankelman and Davidson 1988).

With distinct agro-climatic features, the farm crops are grouped as follows:

·     Field crops (cereals, oilseeds, fibre, sugar and fodder crops) are rain-fed or cultivated through controlled irrigation.

·     Upland and semi-upland cultivation (wheat, groundnuts, cotton and so on) are practised where irrigation or rain water is not abundantly available.

·     Wetland cultivation (rice crops) is practised where the land is ploughed and puddled with 5 to 6 cm of standing water and seedlings are transplanted.

·     Horticulture crops are fruit, vegetable and flower crops.

·     Plantation or perennial crops include coconut, rubber, coffee, tea and so on.

·     Pastures are anything nature grows without human intervention.

Farming Operations, Hand Tools and Machinery

Farming in the tropical countries is labour intensive. The ratio of rural population to arable land in Asia is twice as great as in Africa and three times that of Latin America. It is estimated that human effort provides more than 70% of the energy required for crop production tasks (FAO 1987). Improvement in the existing tools, equipment and methods of work has significant effects in minimizing human strain and fatigue and increasing farm productivity. For field crops, farm activities may be categorized based on the physiological demand of work with reference to an individual’s maximal working capacity (see table 64.5).

Table 64.5 Categorization of farm activities

Work severity

Farm operations

 

Seed bed preparation

Sowing

Weeding and intercultivation

Harvesting

Light work

Laddering (two workers)

Broadcasting seeds/fertilizer, scaring birds, ridging

Fertilizer broadcasting

Grain cleaning, grading, spreading vegetables (squatting), pounding grain (helper), winnowing (sitting)

Moderately heavy work

Walking behind animal-drawn implement, levelling soil surface with wooden rake, laddering (one worker), digging soil with spade, bush cutting

Manual uprooting of seedlings (squatting and bent posture), transplanting seedlings (bent posture), walking on a puddled field

Manual weeding with sickle and hand hoe (squatting and bent posture), channel irrigation, knapsack spraying of pesticides, weeder operation in wet and dry soil

Cutting crops, harvesting paddy, wheat (squatting and bent posture), plucking vegetables, manual winnowing (sitting and standing), cutting sugarcane, pedal-thresher helper, carrying load (20-35 kg)

Heavy work

Ploughing, water lifting (swing busket), hoeing dry soil, bund trimming wet soil, spade work, disc harrowing

 

Weeder operation in dry soil

Grain threshing by beating, pounding grain

Extremely heavy work

Bund trimming dry soil

Germinating seeder operation in puddled field

 

Pedal threshing, carrying load on head or yoke (60-80 kg)

Source: Based on data from Nag, Sebastian and Marlankar 1980; Nag and Chatterjee 1981.

Seed-bed preparation

A suitable seed-bed is one that is mellow yet compact and free from vegetation that would interfere with seeding. Seed-bed preparation involves use of different types of hand tools, shallow chisel desi or a mould board plough pulled by draft animals (figure 64.14) or tractor implements for ploughing, harrowing and so on. About 0.4 hectare (ha) of land can be tilled by a bullock-drawn plough in a day, and a pair of bullocks can provide power to the extent of 1 horsepower (hp).

Figure 64.14 Bullock-drawn shallow chisel desi plough

Pranab Kumar Nag

In using animal-drawn equipment, the worker acts as a controller of animals and guides the implement with a handle. In most cases, the operator walks behind the implement or sits on the equipment (e.g., disc harrows and puddlers). The operation of animal-drawn implements involves considerable human energy expenditure. For a 15 cm plough, a person may walk about 67 km to cover a 1-hectare area. At a walking speed of 1.5 km/h, the human energy expenditure amounts to 21 kJ/min (about 5.6 × 104 kJ per ha). A handle on implements that is too long or too short results in physical discomfort. Gite (1991) and Gite and Yadav (1990) suggested that the optimum handle height of an implement may be adjusted between 64 and 84 cm (1.0 to 1.2 times the metacarpal III height of the operator).

Hand tools (spade, shovel, hoe and so on) are used for digging and loosening the soil. To minimize drudgery in shovelling work, Freivalds (1984) deduced the optimum rate of work (i.e., shovelling rate) (18 to 21 scoops/minute), shovel load (5 to 7 kg for 15 to 20 scoops/minute, and 8 kg for 6 to 8 scoops/minute), throw distance (1.2 m) and throw height (1 to 1.3 m). Recommendations also include a shovel lift angle of about 32°, a long tool handle, a large, square-pointed blade for shovelling, a round-pointed blade for digging and hollow back construction to reduce shovel weight.

Nag and Pradhan (1992) suggested low-lift and high-lift hoeing tasks (see figure 64.15), based on physiological and biomechanical studies. As a general guide, the method of work and the hoe design are the deciding factors in performance efficiency of hoeing tasks (Pradhan et al. 1986). The mode of striking the blade to the ground determines the angle at which it penetrates the soil. For low-lift work, the work output was optimized at 53 strokes/ minute, with a land area dug of 1.34 m2/minute, and a work-rest ratio of 10:7. For high-lift work, the optimal conditions were 21 strokes per minute and 0.33 m2/minute of land dug. The shape of the blade—rectangular, trapezoidal, triangular or circular—depends upon the purpose and preference of the local users. For different modes of hoeing, the recommended design dimensions are: weight 2 kg, angle between blade and handle 65 to 70° , handle length 70 to 75 cm, blade length 25 to 30 cm, blade width 22 to 24 cm and handle diameter 3 to 4 cm.

Figure 64.15 Hoeing tasks in bund trimming in paddy field

Pranab Krumar Nag

Sowing/planting and fertilizer application

The sowing of seeds and planting of seedlings involve the use of planters, seeders, drills and the manual broadcasting of seeds. About 8% of total person-hours are required for broadcasting of seeds and uprooting and transplanting of seedlings.

·     In the broadcasting of seeds/fertilizer by hand, manually operated broadcasters allow uniform distribution with minimum drudgery.

·     Seeding behind a plough consists of sowing of seeds in a furrow opened by a wooden plough.

·     In drilling, seeds are placed in the soil by a seed drill or seed-cum-fertilizer drill. The push/pull force required for a worker to operate the drill (manual or animal-drawn units mounted on wheels) is an important design consideration.

·     Dibbling is the placing of seeds by hand or with a small implement (a dibbler), at an average spacing of 15 × 15 cm or 25 × 25 cm. Abrasion of fingers and bodily discomfort due to bent and squat postures are common complaints.

·     In planting, sugar cane sets are planted at 30 cm length in a furrow; potato seed tubers are planted flat and ridges are made.

·     About 1/3 of the world’s rice is grown by the transplanting system. This is also done for tobacco and some vegetable crops. Usually, germinating seeds are broadcasted densely on a puddled field. The seedlings are uprooted and transplanted to a puddled field by hand or with manual or power-operated transplanters. The operator of a manually operated transplanter walks behind the unit to operate the handle mechanism to pick and transplant the seedlings.

For manual transplanting, the workers are required to be immersed knee deep in mud. The squatting posture used for planting on dry land, with one or two legs flexed at the knee, cannot be adopted in a watered field. About 85 person-hours are required to transplant seedlings for each hectare of land. The awkward posture and static load exert strain on the cardiovascular system and cause low-back pain (Nag and Dutt 1980). Manually operated seeders produce higher work output (i.e., a seeder is about eight times more efficient than transplanting by hand). However, maintaining the balance of the machine (see figure 64.16) in a puddled field requires about 2.5 times more energy than manual transplanting.

Figure 64.16 Operating an improved germinated seeder

Pranab Kumar Nag

Plant protection

Fertilizer, pesticide, herbicide and other chemical applicators are operated by pressure through nozzles or by centrifugal force. Large-scale spraying is based on the hydraulic nozzle spray atomizer, either manually operated or using tractor-mounted equipment. Knapsack sprayers are scaled-down models of vehicle-mounted sprayers (Bull 1982).

·     A compression knapsack sprayer consists of a tank, a pump and a rod with nozzle and hose.

·     A lever-operated knapsack sprayer (10 to 20 l) has an operating lever.

·     A power knapsack sprayer consists of a chemical tank of about 10-litre capacity and an air-cooled engine of 1 to 3 hp. The sprayer and engine unit is mounted on a frame and carried on the operator’s back.

·     A hand-operated bucket sprayer and foot-operated sprayer require two persons for operating the pump and spraying. A rocking sprayer is operated by the rocking (forward and backward) movement of the handle lever.

When carried on the shoulder for prolonged periods, the vibrations of knapsack sprayers/chemical applicators have detrimental effects on the human body. Spraying using a knapsack sprayer results in potential skin exposure (the legs experience 61% of the total contamination, the hands 33%, the torso 3%, the head 2%, and the arms 1%) (Bonsall 1985). Personal protective clothing (including gloves and boots) can reduce the dermal contamination of pesticides (Forget 1991, 1992). The work is quite strenuous, due to carrying of the load on the back as well as continuous operation of the sprayer handle (20 to 30 strokes/minute); in addition, there is the thermoregulatory load due to protective garments. The weight and height of the sprayer, shape of sprayer tank, mounting system and force required to operate the pump are important ergonomic aspects.

Irrigation

Irrigation is a prerequisite for intensive cropping in arid and semi-arid regions. Since time immemorial, various indigenous devices have been used for lifting water. Lifting water by different manual methods is physically strenuous. In spite of the availability of water pump sets (electrical or engine powered), manually operated devices are widely used (e.g., swing baskets, counterpoise water lifts, water wheels, chain and washer pumps, reciprocating pumps).

·     A swing basket is used for lifting water from an irrigation channel (see figure 64.17). The capacity of the basket is about 4 to 6 l and the frequency of operation is about 15 to 20 swings/minute. Two operators work at right angles to the direction of basket motion. The work demands heavy physical activity, with adoption of awkward body movements and posture.

Figure 64.17 Lifting water from irrigation channel using a swing basket

Pranab Kumar Nag

·     A counterpoise water lift consists of a container attached to the end of a horizontal lever which is supported on a vertical pole. The worker exerts force on the counterweight to operate the device.

·     Reciprocating pumps (piston-cylinder type hand pumps) are operated either by hand in reciprocating mode or by pedalling in rotary mode.

Weeding and intercultivation

Undesirable plants and weeds cause losses by impairing crop yields and quality, harbouring plant pests and increasing irrigation cost. Reduction in yield varies from 10 to 60% depending upon the thickness of growth and the kind of weeds. About 15% of human labour is spent in removing weeds during the cultivating season. Women typically comprise a large portion of the workforce engaged in weeding. In a typical situation, a worker spends about 190 to 220 hours weeding one hectare of land by hand or hand hoe. Spades are also used for weeding and intercultivation.

Of several methods (e.g., mechanical, chemical, biological, cultural), mechanical weeding, either by pulling out the weeds by hand or with hand tools like the hand hoe and simple weeders, is useful in both dry and wet land (Nag and Dutt 1979; Gite and Yadav 1990). In dry land, the workers squat on the ground with one or two legs flexed at the knee and remove weeds using a sickle or hand hoe. In watered land, the workers adopt a bent forward stooping posture to remove weeds manually or with the help of weeders.

The physiological demand in using weeders (e.g., blade and rake, projection finger, double sweep type weeders) is relatively higher than in manual weeding. However, the efficiency of work in terms of area covered is significantly better with the weeders than with manual weeding. The energy demand in manual weeding jobs is only about 27% of one’s working capacity, whereas for different weeders, the energy demand goes up to 56%. However, the strain is relatively less in the case of wheel hoe-type weeders, with which it takes about 110 to 140 person-hours to cover one hectare. A wheel hoe-type weeder (push/pull) consists of one or two wheels, a blade, a frame and a handle. A force (push or pull) of about 5 to 20 kilograms of force (1 kgf = 9.81 Newtons) is required, with a frequency of about 20 to 40 strokes per minute. The technical specifications of the wheel hoe-type weeders, however, need to be standardized for better operation.

Harvesting

In rice and wheat crops, harvesting requires 8 to 10% of the total person-hours used in crop production. Despite rapid mechanization in harvesting, large-scale dependence on manual methods (see figure 64.18) will continue for years to come. Hand tools (sickle, scythe and so on) are used in manual harvesting. The scythe is commonly used in some parts of the world, because of its large area of coverage. However, it requires more energy than harvesting with a sickle.

Figure 64.18 Harvesting wheat crop using a sickle

Pranab Krumar Nag

The popularity of the sickle is due to its simplicity in construction and operation. A sickle is a curved blade, with a smooth or serrated edge, attached to a wooden handle. Sickle design varies from region to region, and there is a difference in cardiorespiratory load with different types of sickles. The output varies from 110 to 165 m2/hour, values corresponding to 90 and 60 person-hours per hectare of land. Awkward work postures may lead to long-term clinical complications relating to the back and to the joints of the limbs. Harvesting in a bent posture has the advantage of mobility on both dry and wet land, and it is about 16% faster than squatting; however, a bent posture is 18% more energy demanding than squatting (Nag et al. 1988).

Harvesting accidents, lacerations and incised wounds are common in paddy, wheat and cane sugar fields. The hand tools are primarily designed for right-handed persons, but are often used by left-handed users, who are unaware of the possible safety implications. The important factors in a sickle design are the blade geometry, blade serration, handle shape and size. Based on an ergonomics study, suggested design dimensions of a sickle are: weight, 200 g; total length, 33 cm; handle length, 11 cm; handle diameter, 3 cm; radius of blade curvature, 15 cm; blade concavity, 5 cm. For a serrated sickle: tooth pitch, 0.2 cm; tooth angle, 60°; and ratio of the length of cutting surface to chord length, 1.2. Since the workers perform activities under extreme climatic conditions, health and safety issues are critically important in tropical farming. The cardiorespiratory strain accumulates over long hours of work. Extreme climatic conditions and heat disorders place added stress on the worker and diminish working capacity.

Harvesting machines include mowers, choppers, balers and so on. Power-operated or animal-drawn reapers are also used for harvesting field crops. Combine harvesters (self-propelled or tractor operated) are useful where intensive cultivation is practised and the labour shortage is acute.

Harvesting of sorghum is done by cutting the ear-head and then cutting the plant, or vice versa. The cotton crop is collected in 3 to 5 pickings by hand as the ball matures. Harvesting of potatoes and sugar beets is done manually (see figure 64.19) or by using a blade harrow or digger, which may be animal or tractor powered. In the case of groundnuts, the vines are either pulled manually or removed using diggers, and the pods separated.

Figure 64.19 Manual harvesting of potatoes with a hand hoe

Pranab Krumar Nag

Threshing

Threshing includes separation of grains from the earheads. Age-old manual methods of threshing of grain from the paddy pinnacle are: rubbing the earheads with one’s feet, beating of the harvested crop on a plank, animal treading and so on. Threshing is classified as a moderately heavy task (Nag and Dutt 1980). In manual threshing by beating, (see figure 64.20) one separates about 1.6 to 1.8 kg of grain and 1.8 to 2.1 kg of straw per minute from medium sized paddy/wheat plants.

Figure 64.20 Threshing paddy pinnacle by beating

Pranab Krumar Nag

Mechanical threshers carry out threshing and winnowing operations simultaneously. The pedal thresher (oscillating or rotary mode) increases the output to 2.3 to 2.6 kg of grain (paddy/wheat) and 3.1 to 3.6 kg of straw per min. Pedal threshing (see figure 64.21) is a more strenuous activity than manual threshing by beating. The pedalling and holding of paddy plants on the rolling drum result in high muscular strains. Ergonomic improvements in the pedal thresher may allow a rhythmic pattern of leg work in alternate sitting and standing postures and minimize postural strains. The optimal momentum of the thresher may be reached at about 8 kg weight of the rolling drum.

Figure 64.21 A pedal thresher in operation

Pranab Krumar Nag

Power threshers are gradually being introduced in green revolution areas. Essentially they consist of a prime mover, a threshing unit, a winnowing unit, a feeding unit and a outlet for clean grain. Self-propelled combines are a combination of a harvester and a thresher unit for grain crops.

Fatal accidents have been reported in grain threshing using power threshers and fodder cutters. The incidence of moderate to severe thresher injuries was 13.1 per thousand threshers (Mohan and Patel 1992). Hands and feet can be injured by the rotor. The position of the feeding chute can result in awkward postures when feeding the crop into the thresher. The belt powering the thresher is also a common cause of injuries. With fodder cutters, the operators can sustain injury while feeding the fodder into the moving blades. Children sustain injury when playing with the machines.

The workers often stand on unstable platforms. In the event of a jerk or loss of balance, the torso weight pushes the hands into the threshing drum/fodder cutter. The thresher must be designed so that the feeding chute is at elbow level and the operators stand on a stable platform. The design of the fodder cutter may be improved for safety as follows (Mohan and Patel 1992):

·     a warning roller placed on the chute before the feed rollers

·     a locking pin to fix the flywheel when the cutter is not in use

·     gear cover and blade guards to push limbs away and prevent clothes from getting entangled.

For threshing groundnuts, the traditional practice is to hold the plants by one hand and strike them against a rod or grill. For threshing maize, tubular maize shellers are used. The worker holds the equipment in his or her palm and inserts and rotates cobs through the equipment to separate the maize grains from the cobs. Output with this equipment is about 25 kg/hour. Hand-operated rotary type maize shellers have higher work output, about 50 to 120 kg/hour. The length of the handle, the force required to operate it and the speed of operation are the important considerations in hand-operated rotary maize shellers.

Winnowing

Winnowing is a process to separate grains from chaff by blowing air, using a hand fan or a pedal- or motor-driven fan. In manual methods (see figure 64.22), the whole content is thrown up in the air, and the grain and chaff get separated out by differential momentum. A mechanical winnower may, with considerable human exertion, be hand or pedal operated.

Figure 64.22 Manual winnowing

Pranab Krumar Nag

Other post-harvest operations include cleaning and grading of grains, shelling, decortication, hulling, peeling, slicing, fibre extraction and so on. Different types of manually operated equipment are used in post-harvest operations (e.g., potato peelers and slicers, coconut dehuskers). Decortication involves breaking of shells and removal of seeds (e.g., groundnuts, castor beans). A groundnut decorticator separates kernels from pods. Manual decortication has a very low output (about 2 kg of pod shelling per person-hour). Workers complain of bodily discomfort due to the continuous sitting or squatting posture. Oscillating or rotary-mode decorticators have an output of about 40 to 60 kg of pods per hour. Shelling and hulling refer to separation of seed coat or husk from the inner portion of the grain (e.g., paddy, soybean). Traditional rice hullers are manually (hand or foot) operated and are widely used in rural Asia. The maximum force which can be exerted by hand or foot determines the size and other characteristics of the device. Nowadays, motorized rice mills are used for hulling. In some grains, such as pigeonpea, the seed coat or husk is tightly attached. Removal of the husk in such cases is called dehusking.

For different hand tools and manually operated implements, the grip size and the force exerted on the handles are important considerations. In the case of shears, the force which can be applied by two hands is important. Although most injuries related to hand tools are classified as minor, their consequences are often painful and disabling because of delayed treatment. Design changes in hand tools should be limited to those that can be easily fabricated by village artisans. Safety aspects need to be given due consideration in powered equipment. Safety shoes and gloves available at present are far too expensive and are not suitable for farmers in the tropics.

Manual material-handling tasks

Most agricultural activities involve manual material-handling tasks (e.g., lifting, lowering, pulling, pushing and carrying of heavy loads), resulting in musculoskeletal strains, falls, spinal injuries and so on. The fall injury rate increases dramatically when the fall height is more than 2 m; impact forces are reduced manyfold if the victim falls on soft earth, hay or sand.

In rural areas, loads weighing 50 to 100 kg might be carried several miles on a daily basis (Sen and Nag 1975). In some countries, women and children have to fetch water in large quantities from a distance. These arduous tasks need to be minimized to the extent possible. Different methods of water carriage involve carrying on the head, on the hip, on the back and on the shoulder. These have been associated with a variety of biomechanical effects and spinal disorders (Dufaut 1988). Attempts have been made to improve shoulder load-carrying techniques, designs of wheelbarrows and so on. Load transportation using transverse yoke and head load are more efficient than the frontal yoke. The load optimization that can be carried by men may be obtained from the nomogram shown (figure 64.23). The nomogram is based on a multiple regression drawn between oxygen demand (the independent variable) and load carried and walking speed (the dependent variables). One may put a scale on the graph across the variables to identify the result. Two variables must be known to find the third. For example, with an oxygen demand of 1.4 l/min (approximate equivalent of 50% of one’s maximum working capacity) and walking speed of 30 m/min, the optimum load would be about 65 kg.

Figure 64.23 A nomogram to optimize load to be carried on head/yoke,  with reference to walking speed and oxygen demand of work.

In view of the diversity of farm activities, certain organizational measures towards redesigning of tools and machinery, methods of work, installation of safety guards on machinery, optimization of human exposure to adverse work environment and so on may significantly improve conditions of work for farming populations (Christiani 1990). Extensive ergonomic research on farm methods and practices, tools and equipment may generate a great deal of knowledge for the betterment of health, safety and productivity of billions of agricultural workers. This being the world’s largest industry, the primitive image of the sector, particularly the resource-poor tropical agriculture, could be transformed as task-oriented. Thus rural workers can undergo systematic training on the hazards of jobs, and safe operational procedures can be developed.

MECHANIZATION

Dennis Murphy

The mechanization of agricultural work and work processes has relieved many workers throughout the world of onerous, back-breaking, monotonous labour. At the same time, the speed and power associated with mechanization contributes greatly toward serious traumatic injury. Throughout the world, countries that practise mechanized agriculture list tractors and field and farmstead machinery as leading agents of fatal and disabling injury in agricultural work. Power tools also contribute to the injury toll, though these injuries are usually less severe. Some machinery also presents environmental hazards such as noise and vibration.

Tractor hazards

Farm tractors have many characteristics that result in their being the most important piece of power equipment on the farm. Most tractors have rubber tyres, hydraulic systems, and power take-off (PTO), and utilize a combination of engine speeds and gear ratios. These characteristics combine to provide tractors with speed, power, flexibility and adaptability. The most serious hazards associated with tractor operation include overturns, runovers and PTO entanglement. Tractor overturns fatally injure far more victims than any other type of incident. Table 64.6  provides a listing of tractor hazards and how injuries occur.

Table 64.6 Common tractor hazards and how they occur

Hazard

Type of incident

How injury occurs

Overturns

Side rollovers

Operating on slopes, turning corners too fast, rear wheel drops into a hole or off-road surface.

 

Rear rollovers

Hitching to a point other than the drawbar, rear wheels are stuck in mudhole or are frozen to the ground.

Runovers

Passenger (extra rider) falls off

Most tractors are designed only for one operator; therefore, there is no safe location for an extra person on a tractor.

 

Operator falls off

Knocked off by low-hanging tree limb, bounced out of seat by traversing rough ground.

 

Operator is run over while standing on the ground

Jump starting tractor with tractor inadvertently in gear. Tractor rolls while mounting/dismounting. Tractor rolls during hitching/unhitching of equipment.

 

Bystander or on-ground helper is run over

Bystander incidents often involve small children the operator does not see. On-ground helper incidents are similar to operator-on-the-ground incidents.

Power take-off (PTO)

Entanglement with PTO stub shaft

Master shield is missing and PTO is left engaged while tractor is running. Operator may be mounting/dismounting from rear of tractor.

Slips and falls

Mounting/dismounting from tractor

Wet and/or muddy feet, first/last step is high off the ground, difficult to reach handholds, hurrying, facing wrong way when dismounting.

Noise-induced hearing loss

Operating tractor

The tractor muffler may be missing, damaged, or is a non-recommended replacement; tractor engine is not maintained properly; metal weather cab redirects sound back to the operator. Damaging noise level may come from a combination of tractor and attached machine. (Older tractors generally produce louder sounds than newer tractors.)

Overturns

The central concept in tractor stability/instability is centre of gravity (CG). A tractor’s CG is the point on the tractor where all parts balance one another. For example, when a two-wheel-drive tractor is sitting with all wheels on level ground, the CG is typically about 25.4 cm above and 0.6 m in front of the rear axle and in the centre of the tractor body. For four-wheel-drive and centre-articulated tractors, the CG is located slightly more forward. For a tractor to stay upright, its CG must stay within the tractor’s stability baseline. Stability baselines are essentially imaginary lines drawn between points where tractor tires contact the ground (see figure 64.24). A tractor’s CG as such does not move, but its relationship with stability baselines may change. This most often occurs as the tractor moves out of a perfectly level position, such as onto a slope. A changing relationship between CG and stability baseline means the tractor is moving toward an unstable position. If the CG-stability baseline relationship changes significantly (e.g., the tractor CG moves beyond the stability baseline), the tractor rolls over. If equipment such as a front-end loader, a round bale lifting fork or a chemical side-saddle tank is mounted on the tractor, the additional weight shifts the CG toward that piece of equipment. As mounted equipment is raised, the CG is raised.

Figure 64.24 The stability baseline of a tricycle tractor and a wide front-end tractor, respectively

Other factors important to tractor stability/instability include centrifugal force (CF), rear-axle torque (RAT) and drawbar leverage (DBL). Each of these factors works through the CG. Centrifugal force is the outward force nature exerts on objects that move in a circular fashion. Centrifugal force increases both as the turning angle of the tractor becomes sharper (decreases) and as the speed of the tractor increases during a turn. The CF increase is directly proportional to the turning angle of the tractor. For every degree the tractor is turned tighter, there is an equal amount of increased CF. The relationship between CF and tractor speed, however, is not directly proportional. Finding the increase in CF from turning a tractor at a higher speed (assuming the turning radius stays the same) calls for squaring the difference between the two tractor speeds.

RAT involves energy transfer between the tractor engine and the rear axle of a two-wheel-drive tractor. Engaging the clutch results in a twisting force, called torque, to the rear axle. This torque is then transferred to the tractor tyres. Under normal circumstances, the rear axle (and tyres) should rotate, and the tractor will move ahead. In lay terms, the rear axle is said to be rotating about the tractor chassis. If the rear axle should be unable to rotate, the tractor chassis rotates about the axle. This reverse rotation results in the front end of the tractor lifting off the ground until the tractor’s CG passes the rear stability baseline. At this point the tractor will continue rearward from its own weight until it crashes into the ground or another obstacle.

DBL is another principle of stability/instability related to rear overturns. When a two-wheel-drive tractor is pulling a load, its rear tyres push against the ground. Simultaneously, the load attached to the tractor is pulling back and down against the forward movement of the tractor. The load is pulling down because it is resting on the earth’s surface. This backward and downward pull results in the rear tyres becoming a pivot point, with the load acting as a force trying to tip the tractor rearward. An “angle of pull” is created between the ground’s surface and the point of attachment on the tractor. The heavier the load, and the higher the angle of pull, the more leverage the load has to tip the tractor rearward.

Runovers

There are three basic types of tractor runover incidents. One is when a passenger (extra rider) on the tractor falls off the tractor. A second is when the tractor operator falls off the tractor. The third type occurs when a person already on the ground is run over by the tractor. The person already on the ground may be a bystander (e.g., a non-working adult or a small child), a co-worker or the tractor operator. The tractor runover event often involves trailing machinery hitched to the tractor; it may be the trailing machinery that inflicts the injury. Extra rider injury incidents occur because there is no safe location for an extra person on a tractor, yet the practice of taking extra riders is common, as a means of saving time, for convenience, work assistance or baby-sitting. Whether an extra rider can be justified for any reason is strictly in the eye of the beholder. Safety experts and tractor manufacturers strongly recommend against an operator carrying an extra rider for any reason. This advice, however, conflicts with several factors that farmers must face daily. For instance, it is human nature to want to complete work tasks as easily and quickly as possible; different transportation may call for added expenditure of a meagre money supply; other baby-sitting options simply may not exist; and new tractor drivers must be taught how to operate tractors.

Persons already on the ground, usually tractor operators or children, are occasionally run over by tractors and their attached equipment. Tractor operators sometimes try to start their tractor from the ground, instead of from the operator’s seat. Most of these incidents occur with older tractors that will start with the tractor in gear, or on newer tractors where the starting interlocks built into the tractor have been by-passed. Small children, usually under the age of five, are sometimes run over by tractors and machinery that is moved around the farmstead. Often, the tractor operator is unaware that the child is even near the equipment. A loud noise, such as the start-up of a tractor, is often attractive to young children and may draw them near. And the practice of allowing extra riders may bring them running to the tractor.

Tractor safety rules include:

·     The most important safety device for a tractor is a rollover protective structure (ROPS). This device, along with a properly buckled seat-belt, prevents an operator from being crushed by the tractor during a rollover.

·     A ROPS enclosed cab provides even more protection, as cabs also provide protection from adverse weather elements and from falling off the tractor.

·     A master shield over the PTO stub shaft protects against PTO entanglement.

·     The one seat–one rider rule and other safe operating practices must be followed.

·     Operator manuals must be read to learn how to safely operate the machine.

·     Workers must be physically, psychologically and physiologically capable of operating a given machine.

Machinery Hazards

There are a multitude of machines used in mechanized agriculture. These machines are powered in many different ways including PTO shafts, hydraulic oil pressure, electrical power, engine power and ground traction. Many machines have several types of hazards. Table 64.7  gives machine hazards, descriptions of the hazards and examples of where the hazards occur on various machines.

Table 64.7 Common machinery hazards and where they occur

Hazards

Sources

Locations

Pinch points

Two machine parts moving together with at least one of them moving in a circle

Where drive belts contact pulley wheels, drive chains contact gear sprockets, feed rolls mesh together

Wrap points

An exposed/unguarded rotating machine component

Power take-off (PTO) drive shafts, beater bars on self-unloading ensilage wagons, blades of some manure spreaders

Shear/cutting points

The edges of two moving parts move across one another, or a single edge moves against a stationary edge or soft material

Mowers and forage harvesters, small-grain combine heads, bedding choppers, grain augers

Crush points

Two moving objects moving toward each other, or one moving object moves toward a stationary object

The front and rear tires/sections of articulating tractors, hitching machinery, a hand caught under a piece of hydraulically-controlled equipment

Free-wheeling parts

Machine parts that continue to move after power to the part has stopped, usually from the continuing rotation of knife or fan blades

Forage harvesters, feed grinders, rotary mowers, ensilage blowers

Thrown objects

The chopping, grinding, cutting, and flinging motions of machines. Small objects such as rocks, metal, glass, sticks, and vegetation may be picked up and thrown with great force

Rotary mowers, feed grinders, combines with straw choppers, and manure spreaders

Stored energy

Energy that is confined and released unintentionally or unexpectedly

Machine springs, hydraulic systems, compressed air, electrical systems

Burn points

Skin burns from contacting hot parts of machines

Hot mufflers, engine blocks, pipes, fluids (fuel, oils, chemicals)

Pull-in points

Occurs at the point where the machine takes the crop material in for further processing

Corn pickers and combines, forage choppers, and hay balers

Noise-induced hearing loss

Operating machinery

Tractors, field machinery, grain augers, dryers, silo blowers, bedding choppers, feed grinders. Damaging noise level may come from a combination of one or more machines. Older machines generally produce louder sounds than newer machines.

Machinery power and speed

Though workers may understand that machinery is powerful and operates at very high speeds, most workers have not stopped to consider just how powerful machines are in comparison to their own power, nor do they fully comprehend how fast machines are. Machinery power varies considerably, but even small machines generate many times more horsepower than any person. A quick, pull-away action of a human arm normally generates less than 1 horsepower (hp), sometimes much less. A small 16-hp machine, such as a walk-behind mower, may have 20 to 40 times more power pulling a person into the machine than that person can generate pulling away. A medium-sized machine operated at 40 to 60 hp will have hundreds of times more power than a person.

This power and speed combination presents many potentially hazardous situations to workers. For example, the tractor’s PTO stub shaft transfers power between the tractor and PTO-powered machinery. Power transfer is accomplished by connecting a drive shaft from the machinery to the tractor’s PTO stub. The PTO stub and drive shaft rotate at 540 rpm (9 times/second) or 1,000 rpm (16.7 times/second) when operating at full recommended speed. Most incidents involving PTOs stem from clothing suddenly caught by an engaged but unguarded PTO stub or driveline. Even with a relatively quick reaction of 1 second (i.e., the worker tries to pull away from the shaft) and a shaft with a diameter of 76 mm operating only at half speed (e.g., at 270 rpm (one-half of 540), the victim’s clothing has already wrapped 1.1 m around the shaft. A faster-operating PTO and/or a slower reaction provides even less of an opportunity for the worker to avoid entanglement with the shaft.

When a machine is running at full recommended PTO speed, crop material moves into the machine intake or processing area at approximately 3.7 m/s. If a worker is holding onto crop material as it begins entry into the machine, he or she is usually unable to let go quickly enough to release the material before being pulled into the machine. In 0.3 second, the worker will be pulled 1.1 m into the machine. This situation most often happens when crop material plugs the intake point of the machine and the worker attempts to unplug it with the PTO engaged.

Machinery safety

Machinery safety is largely a matter of keeping the guards and shields that came with the original in place and properly maintained. Warning decals should be used as a reminder to keep guards and shields in place. If guards or shields must be removed for maintenance, service or adjustment, they must be replaced immediately upon completion of the repair. Safe operating practices must be followed. For example, the tractor must be shut off and the PTO or block hydraulic systems disengaged before unplugging or servicing equipment. Operator manuals must be read and their safety instructions followed. Workers must be properly trained.

AGRICULTURAL MACHINERY *

*Adapted from 3rd edition, "Encyclopaedia of Occupational Health and Safety".

Agricultural machinery is designed to till the soil and render it more suitable for crop growth, to sow seeds, to apply agricultural chemicals for improved plant growth and control of pests and diseases, and to harvest and store the mature crops. There is an extremely wide variety of agricultural machines, but all are essentially a combination of gears, shafts, chains, belts, knives, shakers and so on, assembled to perform a certain task. These parts are usually suspended in a frame which may be either stationary or, as is more often the case, mobile and designed to perform the desired operation while moving across a field. The major groups of agricultural machines are: soil tillage machines; planting machines; cultivating machines; forage harvesting machines; grain, fibre, vegetable, and fruit and nut harvesting machines; agricultural chemical applicators; transport and elevating machines; and sorting and packaging machines.

Soil tillage machines. These include ploughs, tillers, subsoilers, harrows, rollers, levellers, graders and so on. They are designed to turn, agitate, level and compact the soil to prepare it for planting. They may be small in size and require only a small power source (as in the case of a one-person roto-tiller for tilling a rice paddy), or they may be large and require a considerable power source (as in the case of a combined subsoiler, drill and harrow).

Planting machines. These include planters, drills, broadcast seeders and so on and are designed to take seeds from a hopper or bin and insert them in the soil at a predetermined depth and spacing or spread them uniformly over the ground. Planters may be of simple design and comprise a single-row seeding mechanism, or they may be highly complex (as is the case with the multi-row planter with attachments that simultaneously add fertilizer, pesticides and herbicides).

Cultivating machines. These include rotary hoes, cultivators, weeders (mechanical and flame) and so on. They are used to eradicate undesirable weeds or grasses which compete with the plant for soil moisture and make the harvest of the crop more difficult. They also improve the soil tillage so as to make it more absorptive of rain.

Forage harvesting machines. These include mowers, choppers, balers and so on and are designed to sever the stems of roughage crops from their roots and prepare them for storage or immediate use. The machines also vary in their complexity: the simple mower merely cuts the crop, whereas the chopper will not only separate the stalk from the root but will also chop the entire plant into small pieces and load it into a vehicle, which may be a towed wagon. Crimpers, which crush or break the stems of plants, are often used to expedite the field-drying process of fodder crops to prevent spoilage, especially of legumes that will be placed in dry storage or baled. Pelleting machines are used to compress fodder crops into compact cubes for mechanical feeding of livestock. Balers are used to compress fodder into square or round bales to facilitate storage and handling. Some bales are small enough (20 to 40 kg) to handle manually, while others may be so large (400 to 500 kg) as to require mechanical handling systems.

Grain and fibre harvesting machines. These include reapers, binders, corn pickers, combines, threshers and so on. They are used to remove the ripe grain or fibre from the plant and place it in a bin or bag for transport to the storage area. Grain harvesting may involve the use of a number of machines, such as a reaper or binder to cut the standing grain, a wagon or truck to transport the crop to the threshing or separating machines and vehicles to transport the grain to a storage area. In other cases many of these functions may be performed by a single machine, the combine harvester (figure 64.25), which cuts the standing grain, separates it from the stalk, cleans it and collects it in a bin, all while moving through the field. Such machines will also load the grain into transport vehicles. Some machines such as cotton pickers and corn pickers may operate selectively and remove only the grain or fibre boll from the stem or stalk.

Figure 64.25 Combine for harvesting wheat without an enclosed cabin

Vegetable harvesting machines. These include diggers and lifters, and are designed either to dig the crops from the earth and separate them from the soil or to lift or pull the plant free. The potato digger, for example, may form part of a potato combine comprising a sorting, grading device, polisher, bagger and elevator. At the other extreme is the simple two-wheeled, bladed sugar-beet lifter which is followed by hand labourers.

Fruit and nut harvesting machines. These machines are used to harvest berries, fruit and nuts. They may be as simple as a tractor-mounted, vibrating tree shaker which separates the ripe fruit from the tree. Or they may be as complex as the ones which harvest the fruit, catch the falling fruit, place it in a storage container and later transfer it to transport vehicles.

Transport and elevating machines. These also vary considerably in size and complexity ranging, for example, from a simple wagon comprising merely a platform on wheels to a self-loading and stacking transport unit. Inclined chain, flight or belt conveyors or other mechanical handling devices are used to move bulky material (hay, straw, ear corn and so on) from wagon to storage or from one location in a building to another. Screw conveyors are used to move granular material and grain from one level to another, and blowers or pneumatic conveyors are used to move light materials horizontally or vertically.

Agricultural chemical applicators. These are used to apply fertilizers to stimulate plant growth or herbicides and pesticides to control weeds and pests. The chemicals may be liquid, powdered or granular, and the applicator distributes them either by pressure through a nozzle or by centrifugal force. Applicators may be portable or vehicle-mounted; the use of aircraft for chemical application is growing rapidly.

Sorting and packaging machines. These machines are usually stationary. They may be as simple as a fanning mill, which grades and cleans grain merely by passing it over a series of screens, or as complex as a seed mill, which will not only grade and clean but also, for example, separate different types of seeds. Packaging machines usually form part of a sophisticated grading system. They are used primarily for fruit and vegetables and may wrap the produce in paper, bag it or insert it into a plastic container.

Power plants. Electric motors may be used to drive stationary equipment permanently located near a mains supply; however, since many agricultural machines are mobile and must operate in remote areas, they are usually powered by an integral petrol engine or by a separate engine such as that of a tractor. Power from a tractor may be transmitted to the machine via belt, chain, gear or shaft drives; most tractors are fitted with a power take-off coupling specially designed for this purpose.

L.W. Knapp, Jr.

RICE

Malinee Wongphanich

Rice is the staple food for Asian people; it is prepared by cooking or ground as flour for bread making, thus helping to feed the rest of the world population. Various kinds of rice are produced to suit the taste of the consumers. Rice cultivation is done either in marshy, lowland areas with plenty of water or in plateau or hilly regions where natural rainfall provides adequate amounts of water.

Cultivation Process

Rice can be cultivated either by hand or by partial or full mechanization, according to the technological development of the country and the need for productivity. Whatever kind of operation is done, the following step-by-step processes are necessary.

1.     Ploughing. The land is ploughed in three stages to eliminate lumps and to make soil as soft and muddy as possible. Buffalo, oxen or cows usually pull the ploughs, though the use of mechanical equipment is increasing.

2.     Weeding is carried out three times by irrigating the land for 5 days at a time and then letting it dry for 5 days. At the end of each cycle, the land is beaten with a heavy wooden tool to kill off young weeds so they may be used as natural fertilizer.

3.     Preparation of seedlings. The seeds are soaked in a large water-filled jar with appropriate concentrations of salt added to make the healthy seeds sink. These healthy seeds are then thoroughly washed, soaked overnight, wrapped in a thick cloth or sack for 2 nights to germinate, sown in the area prepared for them and left to grow for approximately 30 days.

4.     Transplantation. The young plants, in bunches of 3 to 5, are thrust into the mud in rows and grown for 10 days. After about a total of 45 days, the plant is fully grown and begins to bear seeds.

5.     Harvesting. When the plant is about 100 days old, it is usually reaped by hand (see figure 64.26); sickles or similar tools are used for cutting the bearing grains off.

Figure 64.26 Harvesting of rice plants by hand in China, 1992

Lenore Manderson

6.     Drying is done in the open air in the sun, to make the moisture content fall below 15%.

7.     Threshing separates the grain, with its husk or glume, from the stalk. Traditionally, buffaloes or oxen are used to slowly drag the threshing combs over the stalk to force out the grain. Many places use locally made machines for this.

8.     Storage. Grains and hays are stored in barns or silos.

Hazards

Common and specific hazards are as follows:

·     Poor housing, low sanitary standards, inadequate nourishment and the need to drink large quantities of water, which is not always pure, lead to general weakness and fatigue, possible sunstroke, intestinal troubles and diarrhoea.

·     Most injuries caused by farm machinery occur when the workers are not familiar with the machines. Muscles, bones and joints are intensively used, both in dynamic and static loads, causing physical fatigue and resulting in the reduction of work capacity and an increase in traumatic injuries and accidents. Children and adolescents, as well as migrant workers, die from farm injuries each year.

·     Chemical agents, such as fertilizers, strong weedkillers, pesticides and other extensively used substances, increase the hazards both for the workers and the animal or plant foods they consume (e.g., fish, field crabs, water plants, mushrooms, medicinal herbs, field rats or even contaminated water).

·     Diseases (e.g., malaria, tetanus, hookworm, schistosomiasis, leptospirosis, hay fever, farmer’s lung, dermatitis, blepharitis, conjunctivitis, common cold and sunstroke) are very common, as are nutritional disorders (e.g., protein deficiency, toxins), alcoholism, heavy smoking and other addictive habits.

·     The most common occupational diseases are skin diseases. These include: redness and blisters from prickly rice leaves; abrasions and skin injuries caused by prickly plants; calluses of the palms, hands, knees and elbows caused by bad posture and the use of hand tools; skin fungal infections (tinea) due to epidermophytes and Monilia (candida), which may be complicated by secondary sensitization, redness and blisters, frequently due to Staphylococcus bacteria; vesicular dermatitis (small blisters) on the feet sometimes attributed to Rhizopus parasiticus; itch commonly caused by the penetration of the skin by Ancylostoma (hookworms); schistosome dermatitis caused directly or indirectly by contact with water containing blood flukes from nonhuman hosts; and redness, blisters and oedema resulting from insect stings.

·     Respiratory diseases due to organic and inorganic dusts and synthetic chemicals are common. Gram-negative bacterial endotoxin levels in air are high in some countries. Silage gas poisoning of high nitrate soils is also a health problem.

·     Climatic agents such as heat, heavy rain, humidity, high wind, storms and lightning strike both workers and cattle.

·     Psychological stress factors such as economic problems, sense of insecurity, lack of social standing, lack of educational opportunities, lack of prospects and risk of unexpected calamities are particularly common in the developing countries.

Safety and Health Measures

Working conditions should be improved and the health hazards reduced through increased mechanization. Ergonomic interventions to organize the work and working equipment, and systematic training of the body and its movements to ensure good working methods, are essential.

Necessary medical preventive methods should be strictly applied, including the introduction of first aid instruction, the provision of treatment facilities, health promotion campaigns and medical surveillance of workers.

Improvement of housing, sanitary standards, accessible potable water, nutritional environmental hygiene and economic stability are essential for the quality of life of rice field workers.

Applicable International Labour Organization (ILO) Conventions and Recommendations should be followed. These include:

·     The Minimum Age (Agriculture) Convention, 1921 (No.10), provides that children under the age of 14 years may not be employed or work in any public or private agricultural undertakings, or in any branch thereof, when school is in session.

·     The Night Work of Children and Young Persons (Agriculture) Recommendation, 1921 (No.14), requires that each Member State regulate the employment of children under the age of 14 years in agricultural tasks at night, leaving not less than 10 consecutive hours for them to rest. For young persons between the age of 14 and 18 years, the period of rest must consist of not less than 9 consecutive hours.

·     The Plantations Convention, 1958 (No.110), provides that every recruited worker shall be medically examined. This Convention is obviously of great importance for workers of all ages.

·     The Maximum Weight Convention, 1967 (No.127), identified optimum loads that can be handled by 90% of workers for all routine and repetitive manual-handling tasks.

AGRICULTURAL GRAINS AND OILSEEDS

Charles Schwab

Several plants in the grass family, including wheat, rye, barley, oats, corn, rice, sorghum and millet, are valuable agricultural commodities, representing the largest effort in production agriculture. Grains provide a concentrated form of carbohydrates and are an important source of food for animals and humans.

In the human diet, grains make up about 60% of the calories and 55% of the protein, and are used for food as well as beverages. Bread is the most commonly recognized food product made from grains, although grains are also important in the production of beer and liquor. Grain is a basic ingredient in the distillation of neutral spirits that produce liquors with the taste and aroma of grain. Grains also are used to make feed for animals, including pets, working animals and animals raised in the production of meat products for human consumption. 

Grain production can be traced to the beginning of civilization. In 1996, world production of cereal grains was 2,003,380,000 tonnes. This volume has increased more than 10% since the mid-1980s (FAO 1997).

Three of the major grains produced for their oil, also called oilseeds, are soybean, rapeseed and sunflower. Although ten different types of oilseed crops exist, these three account for the majority of the market, with soybean as the leader. Virtually all oilseeds are crushed and processed to produce vegetable oils and high-protein meals. Much of the vegetable oil is used as salad or cooking oils, and meal is used predominantly in animal feeds. World oilseed production in 1996 was 91,377,790 tonnes, almost a 41% increase since 1986 (FAO 1997).

The production of grains and oilseeds is affected by regional factors such as weather and geography. Dry soils and environments restrict corn production, while moist soils deter wheat production. Temperature, precipitation, soil fertility and topography also affect the type of grain or oilseed that can be successfully produced in an area.

For production of grain and oilseed crops, work falls into four areas: seed bed preparation and planting, harvest, storage and transportation of the crop to market or processing facilities. In modern agriculture, some of these processes have changed completely, but other processes have changed little since early civilization. However, the mechanization of agriculture has created new situations and safety issues.

Hazards and Their Prevention

All tools used in grain harvest—from complex combines to the simple scythe—have one aspect in common: they are hazardous. Harvest tools are aggressive; they are designed to cut, chew or chop plant materials placed into them. These tools do not discriminate between a crop and a person. Various mechanical hazards associated with grain harvesting include shear-point, pull-in, crush-point, entanglement, wrap-point and pinch-point. A combine pulls in cornstalks at a rate of 3.7 metres per second (m/s), too quickly for humans to avoid entanglement, even with a normal reaction time. Augers and PTO units used to move grain, rotate and have wrapping speeds of 3 m/s and 2 m/s, respectively, and also pose an entanglement hazard.

Agricultural workers also can experience noise-induced hearing loss from large-horsepower machinery and equipment used in crop production. Axial-vane fans that force heated air through a bin or storage structure to dry grain can generate noise levels of 110 dBA or more. Since grain-drying units often are located near living quarters and are operated continuously throughout a season, they often result in substantial hearing loss in farmworkers as well as family members over long periods of time. Other sources of noise that can contribute to hearing loss are machinery such as tractors, combines and conveying equipment, and grain moving through a gravity spout.

Agricultural workers also can be exposed to significant suffocation hazards by engulfment either in flowing grain or collapsing grain surfaces. A person caught in grain is almost impossible to rescue because of the tremendous weight of grain. Workers can prevent engulfment in flowing grain by always turning off all power sources to the unloading and transporting equipment before they enter an area and locking shut all gravity flow gates. Engulfment in a collapsed grain surface is difficult to prevent, but workers can avoid the situation by knowing the history of the storage structure and the grain it contains. All workers should follow confined-space entry procedures for physical engulfment hazards when working with grain. 

During the harvest, storage and transportation of grains and oilseeds, agricultural workers are exposed to dusts, spores, mycotoxins and endotoxins that can be harmful to the respiratory system. Biologically active dust is capable of producing irritation and/or allergic, inflammatory or infectious responses in the lungs. Workers can avoid or reduce their exposure to dust, or wear personal protective equipment such as mechanical filter respirators or air-supplied respirators in dusty environments. Some handling and storage systems minimize the creation of dust, and additives such as vegetable oils can keep dust from becoming airborne.

In some conditions during storage, grain can spoil and emit gases that pose a suffocation hazard. Carbon dioxide (CO2) can collect above a grain surface to displace oxygen, which can cause impairment in workers if oxygen levels drop below 19.5%. Mechanical filter respirators are useless in these situations.

Another hazard is the potential for fires and explosions that can occur when grains or oilseeds are stored or handled. Dust particles that become airborne when grain is moved create an atmosphere ripe for a powerful blast. Only an ignition source is needed, such as an overheated bearing or a belt rubbing against a housing component. The biggest hazards exist at large port elevators or inland community elevators where huge volumes of grain are handled. Regular preventive maintenance and good housekeeping policies minimize the risk of possible ignition and explosive atmospheres.

Chemicals used at the beginning of the crop production cycle for seed-bed preparation and planting also can pose hazards for agricultural workers. Chemicals can increase soil fertility, reduce competition from weeds and insects and boost yields. The biggest concern for agricultural chemicals hazards is long-term exposure; however, anhydrous ammonia, a compressed liquid fertilizer, can cause immediate injury. Anhydrous ammonia (NH3) is a hygroscopic, or water-seeking, compound, and caustic burns result when it dissolves body tissue. Ammonia gas is a strong lung irritant, but has good warning properties. It also has a low boiling point and freezes on contact, causing another type of severe burn. Wearing protective equipment is the best way to reduce risk of exposure. When exposure occurs, first aid treatment requires immediately flushing of the area with plenty of water.

Grain production workers also are exposed to potential injury from slips and falls. A person can die from injuries in a fall from a height as low as 3.7 m, which is easily exceeded by operator’s platforms on most machinery or grain storage structures. Grain storage structures are at least 9 and up to 30 m tall, reachable only by ladders. Inclement weather can cause slippery surfaces from rain, mud, ice or snow build-up, so the use of guards, handrails and footwear with non-slip soles is important. Devices such as a body harness or lanyard also can be used to arrest the fall and minimize injury.

SUGAR CANE CULTIVATION AND PROCESSING

R.A. Munoz, E.A. Suchman, J.M. Baztarrica and Carol J. Lehtola*

*Adapted from 3rd edition, “Encyclopaedia of Occupational Health and Safety”.

Cultivation

Sugar cane is a hardy crop that is cultivated in tropical and sub-tropical regions for its sucrose content and by-products such as molasses and bagasse (the waste fibrous residue). The plant grows in clumps of cylindrical stalks measuring from 1.25 to 7.25 cm in diameter and reaching 6 to 7 m in height. The cane stalks grow straight upward until the stalk becomes too heavy to hold itself up. It then lies on its side and continues to grow upward. This results in a mature cane field lying on top of itself in a mesh pattern. The sugar cane stalks contain a sap from which sugar is processed. Sugar cane is grown throughout the Caribbean, Central and South America, India, the Pacific Islands, Australia, Central and South Africa, Mauritius and the southern United States. Sugar cane’s main use is for sugar; however, it can be fermented and distilled to produce rum. Bagasse, the cellulose material that remains after pressing, may be used in the production of paper and other products or as a fuel source.

Under favourable conditions and the appropriate use of pesticides and fertilizers, cane grows rapidly. To ensure the maximum sugar content of 1 to 17% of total weight, the cane must be harvested immediately after it reaches its final growth period. The cane fields are burned prior to harvest, to eliminate weeds (without destroying the crop) and to destroy snakes, dangerous insects and other pests that live in the dense growth of the cane fields. Harvesting is done either by hand (machetes are used to cut the cane) or by a sugar cane harvesting machine. Mechanization of sugar cane harvesting has become more prevalent during the 1990s. However, hand harvesting still occurs in many parts of the world, as well as in field locations that are not conducive for harvesting equipment. Large numbers of seasonal or migrant labourers are employed during cane harvesting, especially in areas of hand harvesting.

To retain the sugar content, the cane has to be processed as soon as possible after harvesting; therefore the processing plants (mills) are located near the major areas of sugar cane production. The crop is transported to the mills by tractors, semi trucks or, in some areas, by internal rail systems.

Hazards and their prevention

In areas where hand harvesting prevails, many of the injuries are machete related. These injuries can range from minor cuts to the severing of body parts. Also, the machete is the tool that is most commonly used by the less skilled workers on the farm or plantation. Keeping the machete sharp aids in reducing injuries, since with a sharp machete the worker does not have to swing as hard and can maintain better control over the machete. There are also instances of workers getting into fights with machetes. Safety gloves armoured with chain mesh have been developed to provide protection for the hand from machete-related injuries. The use of steel-toed boots and arm and leg guards will also reduce these types of injuries. Boots will also provide some protection from snake bites. Working with cane also can very easily produce injuries and cuts to the eyes. Eye protection is recommended during hand harvesting, where workers are exposed to the cane stalks. Since cane is grown in tropical and sub-tropical locations, workers also need to be concerned about heat-related health problems. This can be exacerbated due to use of the necessary protective clothing. These regions are also areas of high levels of sun exposure, which can result in various types of skin cancer conditions. Precautions need to be taken to limit or protect against sun exposure.

Manual harvesting with machetes can also result in musculoskeletal injuries from the repetitive motions and physical effort. The size of the machete, sharpness and frequency of cutting strokes are factors that affect this. See also the article “Manual operations in farming” in this chapter.

Precautions need to be taken to prevent infection when cuts and abrasions occur. Where the harvesting has become mechanized, hazards exist that are associated with the particular machine being used. These are similar to those of other agricultural harvesting equipment.

Pesticides and other chemicals may involve toxic risks that can lead to poisoning through skin absorption or inhalation. People who apply the pesticides need to be instructed on the hazards of the operation and provided with protective clothing and adequate washing facilities. Their equipment needs to be maintained and repaired as needed in order to prevent spills. Back-pack sprayers are particularly prone to develop leaks that will cause spillage onto the person. Aerial applications of pesticides can affect other people that are in the area of the application. Also, when pesticides are applied, the product label provides both legal and practical requirements for handling and disposal after use, as well as listing time intervals after which it is safe for people to re-enter the field.

Sugar Cane Mills (Processing Plants)

The sugar cane industry is concerned with more than the production of food for human consumption. Certain kinds of sugar and sugar residues provide nutritious supplementary food for animals, and various products of commercial significance are obtained from the raw material and its by-products.

Principal by-products are saccharose, glucose, levulose, raffinose, pectin, waxes and betaines. Subproducts are stalks (used for fodder), bagasse, rum and molasses. Among products manufactured on an industrial scale are saccharose octacetate, ethyl alcohol and acetic, citric, glutamic, oxalic, formic and saccharic acids. Paper and hardboard are produced industrially from bagasse. Bagasse can also, when dried, be used as a biogas source or as fuel in the sugar mill.

In the sugar mill, the cane is crushed and the juice extracted by heavy rollers. The juice contains saccharose, glucose, levulose, organic salts and acids in solution, and is mixed with bagasse fibres, grit, clay, colouring matter, albumin and pectin in suspension. Because of the properties of albumin and the pectin, the juice cannot be filtered cold. Heat and chemicals are required to eliminate the impurities and to obtain saccharose.

The mixture is clarified by heating and the addition of lime-based precipitants. Once clarified, the juice is concentrated by vacuum evaporation until it precipitates in the form of grayish crystals. The concentrated juice, or molasses, is 45% water. Centrifugal treatment produces granulated sugar of a grayish hue (brown sugar), for which there is a market. White sugar is obtained by a refining process. In this process, the brown sugar is dissolved with various chemicals (sulphuric anhydride, phosphoric acid) and filtered with or without bone black, according to the purity desired. The filtered syrup evaporates under a vacuum until it crystallizes. It is then centrifuged until a white crystalline powder is obtained.

Hazards and their prevention

Worker conditions will vary according to geographical locale. Seasonal workers are especially vulnerable to living in substandard conditions. Health risks will vary in relation to the environmental factors, working conditions, living conditions and the socioeconomic class of the worker.

Due to the high temperatures in the areas where cane is produced, workers need to consume large quantities of liquid.

Fumes and gases such as carbon dioxide, sulphur dioxide, carbon monoxide and hydrochloric acid may be given off at various stages of the refining process. The high temperatures of processing can also result in fumes and steam that are not only irritating or hot, but sometimes can be toxic as well.

In some areas of the mill, there are excessive noise levels.

Bagassosis is an occupational lung disease of the extrinsic allergic alveolitis type, caused by breathing dusts containing spores of thermophilic actinomycetes which grow in stored, mouldy bagasse. Hypersensitivity pneumonitis can also result from this exposure.

In developing countries, workers may be unskilled, with no safety training. Also there may be a high turnover rate for employees, which can lead to problems in keeping up with training and increasing skill levels. Although statistical data do not show a high incidence of occupational disease, this can be due in part to reporting and calculating problems, such as the fact that the mills and refining plants are not open year-round, but only for 5 to 6 months of the year. Thus annual accident rates may appear low. During the remainder of the year, seasonal workers will be employed in entirely different jobs, while permanent employees will be maintaining and working with the machinery, equipment and facilities.

Occupational accidents, such as falls, strains, sprains and so on, differ little from those in other industrial and agricultural activities. With increasing mechanization, the occupational accidents are fewer but are often more serious. The more frequent injuries include diseases related to heat stroke or heat stress, dermatitis, conjunctivitis, burns and falls.

In order to plan and put into effect a health and safety programme for a specific sugar mill, it is necessary to conduct a qualitative and quantitative assessment of the risks and hazards involved, including identification of corrective measures, such as the use of local exhaust systems for dust, gas and fumes where appropriate. Dust control can be used effectively for controlling bagasse dust. The facility should be properly aired and ventilated to reduce excessive heat, and adequate lighting should be provided. Machinery should be properly guarded, and proper protective clothing should be provided and easily accessible to workers. Health and safety standards and regulations must be complied with. A proper safety programme, for which trained staff are responsible, to ensure the safety of the workers should be in place.

Noise is a widespread hazard. Noisy machines should be soundproofed, and, in areas where the noise level cannot be reduced adequately, hearing protection must be provided and a hearing conservation programme instituted. That programme should include audiometric testing and worker training.

POTATO HARVESTING

Steven B. Johnson

Roots and tubers are a major part of the diet, food energy and nutrient source for more than 1 billion people in the developing world. Root crops are used to produce food products including composite flours, noodles, chips and dehydrated products. They provide about 40% of the diet for half of the sub-Saharan African population. Cassava has become one of the developing world’s most important staples, providing a basic diet to about 500 million people. Cassava has also become an important export crop for animal feed in Europe.

Roots and tubers—potatoes, sweet potatoes, cassava, yams and taro—are known as the starchy foods. They are high in carbohydrates, calcium and vitamin C, but low in protein. These foods are the subsistence crops in some of the poorest countries. Several root food crops are staples in major world regions. These include the yam in Indochina, Indonesia and Africa; the potato in South America, Central America, Mexico and Europe; and the cassava and sweet potato in South America (Alexandratos 1995).

The potato was introduced into Ireland in the 1580s, and a small plot could feed a six-child family, a cow and a pig. Moreover, the crop could remain in the soil protected from the winter freezes and fires. The potato became the food of the poor in Ireland, England, France, Germany, Poland and Russia. In 1845, a blight struck the potato across Europe, which resulted in the great, fatal potato famine in Ireland, where substitute crops were unavailable (Tannahill 1973).

The potato is still a principal crop in the developed world. Its production continues to increase in the United States, and much of this increase is attributed to processed potatoes. Growth in processed potatoes is occurring in chips and shoestrings, frozen French fries, other frozen products and canned potatoes. The principal occupational hazards are related to injury and are experienced during the mechanical harvesting operation. In a Canadian study, potato farmers were found to be at elevated risk of pancreatic cancer, but no association was made with an exposure.

Hazards

Each moving part of the potato harvester carries the potential for injury. The tractor’s PTO shaft, which connects the tractor and the harvester by universal joints or yokes, is the source of kinetic energy and of injuries. The PTO shaft should be shielded. The most common injury on a PTO shaft occurs when the yoke catches a loose piece of clothing, entangling the wearer.

All hydraulic systems operate under pressure, even as much as 2,000 pounds per square inch (14,000 Kpa), which is three times the pressure needed to penetrate skin. Thus a worker should never cover a leaking hydraulic hose with a finger since the fluid could be injected through the skin. If any fluid is injected into the skin, it must be surgically removed within a few hours or gangrene may develop. If any point in the hydraulic system fails, a serious injury can occur. A ruptured hydraulic hose can spray fluid a great distance. Hydraulic systems store energy. Careless servicing or adjusting can lead to injury.

A pinch-type injury can occur where two machinery parts move together and at least one of them moves in a circle. Gear and belt drives are examples of pinch points. Clothing or body parts can catch and become drawn into the gears. Proper guarding of potato harvester parts reduces the chance of a pinch-type injury.

A wrap-type injury can occur when an exposed, unshielded rotating component, such as a PTO shaft, entangles a loose piece of clothing: a sleeve, a shirt-tail, a frayed piece of clothing or even long hair. Smooth PTO shafts with rust or nicks can be rough enough to catch clothing; a slowly rotating PTO shaft must still be regarded with caution. However, the rounder, smoother shafts are less likely to catch clothing than square shafts. The universals at the end of the PTO shafts are the most likely to catch loose clothing and cause a wrap-type injury. These bulky parts extend beyond the PTO shaft and can cause a wrap-type injury even if one is clear of the PTO shaft. PTO shafts from the tractor to the potato harvester must be guarded. No one should work amid unsafe conditions such as unshielded PTO shafts.

Shear points are areas where two pieces move in a cutting motion. A finger placed in a boom joint or between a fan belt and the pulley would be quickly severed. The belt, turned by the engine that drives the fan, is a site for amputation as well as other bodily injuries. Again, proper shielding of potato harvester parts reduces the chance of a shear injury.

Crush points are found where two objects move towards each other, or an object moves toward a stationary object. Big trucks are involved in a potato harvest. Movement in the field and especially in a closed facility such as a potato storage building can lead to runovers and crushed feet or legs.

A pull-in injury occurs when a worker is pulled into machinery. Pull-in injuries can occur any time there is an attempt to remove something from a potato harvester while it is operating, even if it is not moving forward.

Thrown-object injuries occur when projectiles are hurled. Air-assisted potato harvesters routinely throw soil and small rocks in the process of separating potato tubers from rocks. The soil and debris are thrown with enough force to cause eye injuries.

Prevention

Fortunately, there is a great deal that can be done to avoid injuries. Clothing can make the difference between being caught in a pinch or wrap point and being safe. Loose, long hair can catch in wrap and pinch points and drag the worker’s head into a dangerous spot. Long hair should be securely tied. Skid-resistant shoes help keep the worker from slipping while standing on the sorting platform, which may be treacherous with mud and vines. Gloves, if worn while working on the sorting table, should be tight fitting and not have frayed edges or floppy cuffs.

Attitude, alertness and avoiding dangerous situations complement safe attire. No one should ever mount or dismount a potato harvester while it is in motion. The rider must wait until the harvester stops. Many of the serious and debilitating injuries occur from falling and being crushed while attempting to mount or dismount a moving harvester. One should try to be in a stable position before the tractor starts to pull the potato harvester. This will reduce the possibility of falling down as the tractor jerks forward. No one should ever be between the tractor and the harvester while they are in motion or when they are started. The tractor operator or the workers riding the potato harvester should never be close enough to touch the PTO shaft while it is running or when it is started. Harvesters should not be lubricated, adjusted or repaired while running. No attempt to dislodge anything from the belts should be made while they are in motion.

VEGETABLES AND MELONS

B.H. Xu and Toshio Matsushita

A wide variety of vegetables (herbaceous plants) is grown for edible leaves, stems, roots, fruits and seeds. Crops include leafy salad crops (e.g., lettuce and spinach), root crops (e.g., beets, carrots, turnips), cole crops (cabbage, broccoli, cauliflower) and many others grown for their fruit or seed (e.g., peas, beans, squashes, melons, tomatoes).

Since the 1940s, the nature of vegetable farming, particularly in North America and Europe, has changed dramatically. Previously, most fresh vegetables were grown close to population centres by garden or truck farmers and were available only during or shortly after harvest. The growth of supermarkets and the development of large food-processing companies created a demand for steady, year-round supplies of vegetables. At the same time, large-scale vegetable production on commercial farms became possible in areas far from major population centres because of rapidly expanding irrigation systems, improved insect sprays and weed control, and the development of sophisticated machinery for planting, spraying, harvesting and grading. Today, the main source of fresh vegetables in the United States is long-season areas, such as the states of California, Florida, Texas and Arizona, and Mexico. Southern Europe and North Africa are major vegetable sources for northern Europe. Many vegetables are also grown in greenhouses. Farmers’ markets selling local produce, however, remain the major outlet for vegetable growers throughout much of the world, particularly in Asia, Africa and South America.

Vegetable farming requires substantial skills and care to ensure production of high-quality vegetables that will sell. Vegetable farming operations include soil preparation, planting and growing crops, harvesting, processing and transportation. Weed and pest control and water management are crucial.

Vegetable and melon workers are exposed to many occupational hazards in their working environment, which include plants and their products, agrochemicals for controlling pests and oils and detergents for maintaining and repairing machinery. Manual or automatic work also forces the workers into uncomfortable positions (see figure 64.27). Musculoskeletal disorders such as low-back pain are important health problems in these workers. Agricultural tools and machines used with vegetables and melons give rise to high risks for traumatic injuries and various health impairments similar to those seen in other agricultural work. In addition, outdoor growers are exposed to solar radiation and heat, whereas exposure to pollens, endotoxins and fungi should be taken into account among greenhouse farmers. Therefore, a wide variety of work-related disorders can be found in those populations.

Figure 64.27 Manual labour on a vegetable farm near Assam, Jordan

Food allergies to vegetables and melons are well known. They are mostly provoked by vegetable allergens and can cause an immediate reaction. Clinically, mucocutaneous and respiratory symptoms appear in most patients. Occupational allergy among vegetable workers differs from food allergy in several ways. Occupational allergens are diverse, including those of vegetable origin, chemicals and biological derivatives. Artichoke, brussels sprouts, cabbage, carrot, celery, chicory, chive, endive, garlic, horseradish, leek, lettuce, okra, onion, parsley and parsnip have been reported to contain vegetable allergens and to sensitize vegetable workers. Occupational allergies to melon allergens, however, are seldom reported. Only a few allergens from vegetables and melons have been isolated and identified because of the difficulty and complexity of the laboratory techniques required. Most allergens, especially those of vegetable origin, are fat soluble, but a few are water soluble. The ability to sensitize also varies depending on botanical factors: The allergens may be sequestered in resin canals and released only when the vegetables are bruised. However, in other cases they may be readily released by fragile grandular hairs, or be excreted onto the leaf, coat the pollens or be widely disseminated by the action of wind on trichomes (hair-like growths on the plants).

Clinically, the most common occupational allergic diseases reported in the vegetable workers are allergic dermatitis, asthma and rhinitis. Extrinsic allergic alveolitis, allergic photodermatitis and allergic urticaria (hives) can be seen in some cases. It should be emphasized that vegetables, melons, fruits and pollens have some allergens in common or cross-reacting allergens. This implies that atopic persons and individuals with an allergy to one of those may become more susceptible than others in the development of occupational allergies. To screen and diagnose these occupational allergies, a number of immune tests are currently available. In general, the prick test, intradermal test, measurement of allergen-specific IgE antibody and in vivo allergen challenge test are used for immediate allergies, whereas the patch test can be chosen for delayed-type allergy. The allergen-specific lymphocyte proliferation test and cytokine production are helpful in diagnosing both types of allergy. These tests can be performed using native vegetables, their extracts and released chemicals.

Dermatoses such as pachylosis, hyperkeratosis, nail injury chromatosis and dermatitis are observed in vegetable workers. In particular, contact dermatitis, both irritant and allergic, occurs more frequently. Irritant dermatitis is caused by chemical and/or physical factors. Vegetable parts such as thrichomes, spicules, coarse hairs, raphides and spines are responsible for most of this irritation. On the other hand, allergic dermatitis is classified into immediate and delayed types on the basis of their immunopathogenesis. The former is mediated through humoural immune responses, whereas the later is mediated through cellular immune responses.

Clinically, many patients with allergic dermatitis experience a range of symptoms including itching, erythema, rash, swelling and vesicles. The sites of lesions are mainly the hands, arms, face and neck. In a field survey of Japanese okra growers (Nomura 1993), more than 50% of farmers had skin lesions, and these appeared mostly on the hands and arms. About 20 to 30% of farmers showed a positive patch test reaction to okra pad or leaf extracts. Furthermore, proteolytic activity of okra extracts was shown to cause the skin lesions.

Agricultural chemicals are also important allergens responsible for allergic dermatitis. These include insecticides (DDVP, diazinon, EPN, malathion, naled, parathion and so on), fungicides (benomyl, captafol, captan, maneb, manzeb, nitrofen, plondrel®, thiram, zineb, ziram and so on), herbicides (carbyne, randox and so on) and fumigants (D-D® mixture of 1,3-dichloropropene and 1,1,2-dichloropropane and related compounds). Additionally, opportunistic bacteria and Streptococcus pyogenes are found to play an important role in allergic dermatitis and urticaria for vegetable workers.

Vegetable workers, especially those working in greenhouses or indoors, are exposed to many vegetable products and to compounds such as pesticides, which are responsible for increased lung diseases. In a national study conducted among Swiss farmers, it was documented that the age-standardized proportional mortality for all lung diseases, bronchitis and asthma, and asthma alone were 127, 140 and 137, respectively. Vegetable products can directly cause occupational allergic asthma, or provide non-specific irritants and/or the vehicle for other allergens including pollens, spores, mites and other substances. Vegetable products which can cause allergic asthma are bromelin, castor beans and wax, freesia, grain pollen, guar gum, papain, paprika, hops, ipecacuanha, plicatic acid, quillaic acid, saponin and sunflower pollen.

Fungi in the work environment produce many spores, some of which cause allergic asthma and/or extrinsic allergic alveolitis. However, it is rare that allergic asthma and extrinsic allergic alveolitis from those allergens occur in the same subjects. As for the causative micro-organisms, Alternaria, Aspergillus niger, Cladosporium, humidifier sludge, Merulius lacrymans, Micropolyspora faei, Paecilomyces and Verticillium have been identified. In most cases, antigens of fungal origin are present in spores and breakdown products.

Patients with occupational asthma caused by vegetable products always show elevated serum IgE antibody, eosinophilia and a positive prick test, whereas specific precipitating antibody, positive prick test and distinct radiological findings are seen in patients with extrinsic allergic alveolitis. In addition to pulmonary allergy to vegetable products and fungi spores, nasal symptoms are provoked in atopic patients when handling vegetables such as carrots and lettuce. Gastrointestinal complaints are not generally found.

Agrochemicals are applied for various purposes both in indoor and outdoor vegetable growing. Among the chemicals used, some have been found to have asthmatic potential. They include captafol, chlorothalonil, creosote, formaldehyde, pyrethrin and streptomycin. The improper uses of pesticides potentially can result in soil and vegetable contamination. The application of pesticides without suitable personal protective equipment can lead to both acute or chronic toxic effects.

BERRIES AND GRAPES

William E. Steinke

This article covers the injury and illness prevention methods against hazards commonly encountered in production of grapes (for fresh consumption, wine, juice or raisins) and berries, including brambles (i.e., raspberries), strawberries and bush berries (i.e., blueberries and cranberries).

Grapevines are stems that climb on supporting structures. Vines planted in commercial vineyards are usually started in spring from year-old rooted or grafted cuttings. They are typically planted 2 to 3.5 m apart. Each year, the vines must be dug over, fertilized, subdivided and pruned. The style of pruning varies in different parts of the world. In the system prevalent in the United States, all the shoots except the strongest ones on the vine are later pruned; the remaining shoots are cut back to 2 or 3 buds. The resulting plant develops a strong main stem which can stand alone, before it is allowed to bear fruit. During the expansion of the main stem, the vine is loosely tied to an upright support 1.8 m tall or higher. After the fruit-producing stage is reached, the vines are carefully pruned to control the number of buds.

Strawberries are planted in early spring, midsummer or later, depending on the latitude. The plants bear fruit in the spring of the following year. A variety called everbearing strawberries produces a second, smaller crop of fruit in the fall. Most strawberries are propagated naturally by means of runners that form about two months after the planting season. The fruit is found at ground level. Brambles such as raspberries are typically shrubs with prickly stems (canes) and edible fruits. The underground parts of brambles are perennial and the canes biennial; only second-year canes bear flowers and fruits. Brambles grow fruit at heights of 2 m or less. Like grapevines, berries require frequent pruning.

Growing practices differ for each fruit species, depending on the type of soil, climate and fertilizer it needs. Close control of insects and diseases is essential, often requiring frequent application of pesticides. Some modern growers have shifted toward biological controls and careful monitoring of pest populations, spraying chemicals only at the most effective times. Most grapes and berries are harvested by hand.

In a study of non-fatal injuries for the 10-year period 1981 through 1990 in California, the most common injury within this category of farms was sprains and strains, accounting for 42% of all injuries reported. Lacerations, fractures and contusions accounted for another 37% of injuries. The most common causes of injuries were being struck by an object (27%), overexertion (23%) and falls (19%) (AgSafe 1992). In a 1991 survey, Steinke (1991) found that 65% of injuries on farms identified as producing this category of crops in California were strains, sprains, lacerations, fractures and contusions. Parts of the body injured were fingers (17%), the back (15%), eyes (14%) and the hand or wrist (11%). Villarejo (1995) reported that there were 6,000 injury claims awarded per 100,000 full-time equivalents to workers in strawberry production in California in 1989. He also noted that most workers do not find employment throughout the year, so that the percentage of workers who suffer injuries could be several times higher than the 6% figure reported.

Musculoskeletal Problems

The major hazard associated with musculoskeletal injuries in these crops is rate of work. If the owner is working in the fields, she or he is typically working quickly to finish one task and move on to the next task. Hired labour is often paid by piece-rate, the practice of paying for work solely based upon what is accomplished (i.e., kilograms of berries harvested or number of grapevines pruned). This type of payment is often at odds with the extra time required to make sure fingers are out of the clipper before squeezing, or carefully walking to and from the edge of the field when exchanging filled baskets for empty ones during harvest. A high rate of work performance can lead to using poor postures, taking undue risks, and not following good safety practices and procedures.

Hand pruning of berries or vines requires the frequent squeezing of the hand to engage a clipper, or the frequent use of a knife. Hazards from the knife are obvious, as there is no solid surface against which to place the vine, shoot or stalk and frequent cuts to the fingers, hands, arms, legs and feet are likely to result. Pruning with a knife should be done only as a last resort.

Although a clipper is the preferred tool for pruning, either in the dormant season or while foliage is on the plants or vines, its use does have hazards. The major safety hazard is the threat of cuts from contact with the open blade while placing a vine or stalk in the jaws, or from inadvertent cutting of a finger while also cutting a vine or stalk. Sturdy leather or cloth gloves are good protection against both hazards and can also provide protection against contact dermatitis, allergies, insects, bees and cuts from a trellis.

The frequency and effort required for cutting determines the likelihood of development of cumulative-trauma injuries. Although injury reports do not currently show widespread injury, this is believed to be due to the frequent job rotation found on farms. The force required to operate a common clipper is in excess of recommended values, and the frequency of effort indicates the potential for cumulative-trauma disorders, according to accepted guidelines (Miles 1996).

To minimize likelihood of injury, clippers should be kept well lubricated and blades should be sharpened frequently. When large vines are encountered, as they are frequently in grapes, the size of the clipper should be increased accordingly, so as not to overload the wrist or the clipper itself. Lopping shears or pruning saws are often required for safe cutting of large vines or plants.

Lifting and carrying of loads is typically associated with harvesting of these crops. The berries or fruit are usually hand harvested and carried in some type of basket or carrier to the edge of the field, where they are deposited. Loads are often not heavy (10 kg or less), but the distance to be travelled is significant in many cases and over uneven terrain, which may also be wet or slippery. Workers should not run on the uneven terrain and should maintain solid footing at all times.

Harvesting of these crops is often done in awkward postures and at a rapid pace. Persons typically twist and bend, bend to the ground without bending the knees and move quickly between the bush or vine and the container. Containers are sometimes placed upon the ground and pushed or pulled along with the worker. Fruit and berries can be found anywhere from ground level to 2 m in height, depending upon the crop. Brambles are typically found at heights of 1 m or less, leading to almost continuous bending of the back during harvest. Strawberries are at ground level, but workers remain on their feet and bend down to harvest.

Grapes are also commonly cut to free them from the vine during hand harvest. This cutting motion is also very frequent (hundreds of times per hour) and requires sufficient force to cause concern regarding cumulative-trauma injuries if the harvest season were to last more then a few weeks.

Working with trellises or arbours is often involved in production of vines and berries. Installing or repairing arbours frequently involves doing work at heights above one’s head and stretching while exerting a force. Sustained effort of this type can lead to cumulative injuries. Each instance is an exposure to strain and sprain injury, particularly to the shoulders and arms, resulting from exerting significant force while working in an awkward posture. Training plants on trellises requires the exertion of substantial force, a force that is increased by the weight of the vines, foliage and fruit. This force is commonly exerted through the arms, shoulders and back, all of which are susceptible to both acute and long-term injury from such overexertion.

Pesticides and Fertilizers

Grapes and berries are subject to frequent pesticide applications for control of insects and disease pathogens. Applicators, mixers, loaders and anyone else in the field or assisting with the application should follow the precautions listed on the pesticide label or as required by local regulations. Applications in these crops can be particularly hazardous because of the nature of the deposit required for pest control. Frequently, all portions of the plant must be covered, including the undersides of the leaves and all surfaces of the fruit or berries. This often implies use of very small droplets and the use of air to promote canopy penetration and deposit of the pesticide. Thus many aerosols are produced, which can be hazardous through inhalation, ocular and dermal exposure routes.

Fungicides are frequently applied as dusts to grapes and many types of berries. The most common of these dusts is sulphur, which may be used in organic farming. Sulphur can be irritating to the applicator and to others in the field. It has also been known to reach air concentrations sufficient to cause explosions and fires. Care should be taken to avoid travelling through a cloud of sulphur dust with any possible ignition source, such as an engine, electric motor or other spark-producing device.

Many fields are fumigated with highly toxic materials before these crops are planted in order to reduce the population of such pests as nematodes, bacteria, fungi and viruses before they can attack the young plants. Fumigation usually involves injection of a gas or liquid into the soil and covering with a plastic sheet to prevent the pesticide from escaping too soon. Fumigation is a specialized practice and should be attempted only by those properly trained. Fumigated fields should be posted with warnings and should not be entered until the cover has been removed and the fumigant has dissipated.

Fertilizers may generate hazards during their application. Inhalation of dust, skin contact dermatitis and irritation of the lungs, throat and breathing passages may occur. A dust mask may be useful in reducing exposure to non-irritating levels.

Workers may be required to enter fields for culturing operations such as irrigation, pruning or harvest soon after pesticides have been applied. If this is sooner than the re-entry interval specified by the pesticide label or local regulations, protective clothing must be worn to protect against exposure. The minimum protection should be a long-sleeved shirt, long-legged pants, gloves, head covering, foot coverings and eye protection. More stringent protection, including a respirator, impermeable clothing and rubber boots may be required based upon the pesticide used, time since the application and regulations. Local pesticide authorities should be consulted to determine the proper level of protection.

Machine Exposures

The use of machinery in these crops is common for soil preparation, planting, weed cultivation and harvest. Many of these crops are grown on hillsides and uneven fields, increasing the chance for tractor and equipment rollovers. General safety rules of tractor and equipment operation to avoid rollovers should be followed, as should the policy of no riders on equipment unless additional personnel must be present for proper equipment operation and a platform is provided for their safety. More information on proper use of equipment can be found in the article “Mechanization” in this chapter and elsewhere in this Encyclopaedia.

Many of these crops are also grown in uneven fields, such as on beds or ridges or in furrows. These features increase the danger when they become muddy, slippery or concealed by weeds or the plant canopy. Falling in front of equipment is a hazard, as is falling and straining or spraining a body part. Extra precautions should be taken particularly when fields are wet or at harvest, when discarded fruit may be underfoot.

Mechanical pruning of grapes is increasing around the world. Mechanical pruning typically involves rotating knives or fingers to gather vines and draw them past stationary knives. This equipment can be hazardous to anyone in the vicinity of the entry point for the cutters and should be used only by a properly trained operator.

Harvest operations typically use several machines at once, requiring coordination and cooperation of all equipment operators. Harvesting operations also, by their very nature, include crop gathering and removal, which frequently requires the use of vibrating rods or paddles, stripping fingers, fans, cutting or slicing operations and rakes, any of which are capable of causing great physical harm to persons who become entangled in them. Care should be taken to not place any person near the intake of such machines while they are running. Machine guards should always be kept in place and maintained. If guards must be removed for lubrication, adjustment or cleaning, they should be replaced before the machine is started again. Guards on an operating machine should never be opened or removed.

Other Hazards

Infections

One of the most common injuries suffered by workers in grapes and berries is a cut or puncture, either from thorns on the plant, tools or the trellis or support structure. Such open wounds are always subject to infection from the many bacteria, viruses or infectious agents present in fields. Such infections can cause serious complications, even loss of limb or life. All field workers should be protected with an up-to-date tetanus immunization. Cuts should be washed and cleaned, and antibacterial agent applied; any infections that develop should be treated by a physician immediately.

Insect bites and bee stings

Field workers tending and harvesting are at an increased risk of insect bites and bee stings. Placing hands and fingers into the plant canopy to select and grasp ripe fruit or berries increases the exposure to bees and insects that may be foraging or resting in the canopy. Some insects may be feeding on the ripe berries also, as could rodents and other vermin. The best protection is to wear long sleeves and gloves whenever working in the foliage.

Solar radiation

Heat stress

Exposure to excessive solar radiation and heat can easily lead to heat exhaustion, heat stroke or even death. Heat added to the human body through solar radiation, the effort of work and heat transfer from the environment must be removed from the body through sweat or sensible heat loss. When ambient temperatures are above 37 °C (i.e., normal body temperature), there can be no sensible heat loss, so the body must rely solely on perspiration for cooling.

Perspiration requires water. Anyone working in the sun or in a hot climate should drink plenty of fluids over the entire day. Water or sports drinks should be used, even before one feels thirsty. Alcohol and caffeine should be avoided, as they tend to act as diuretics and actually speed water loss and interfere with the body’s heat-regulating process. It is often recommended that persons drink 1 litre per hour of work in the sun or in hot climates. A sign of drinking insufficient fluids is the lack of the need to urinate.

Heat-related diseases can be life-threatening and require immediate attention. Persons suffering from heat exhaustion should be made to lie down in the shade and drink plenty of fluids. Anyone suffering from heat stroke is in grave danger and needs immediate attention. Medical assistance should be summoned immediately. If assistance is not available within a matter of minutes, one should attempt to cool the victim by immersing him or her in cool water. If the victim is unconscious, continued breathing should be assured through first aid. Do not give fluids by mouth.

Signs of heat-related diseases include excessive sweating, weakness in the limbs, disorientation, headaches, dizziness and, in extreme cases, loss of consciousness and also loss of the ability to sweat. The latter symptoms are immediately life-threatening, and action is required.

Working in vineyards and bush berry fields may increase the risk of heat-related illnesses. Air circulation is reduced between the rows, and there is the illusion of working partially in the shade. High relative humidity and cloud covers can also give one a false impression of the effects of the sun. It is necessary to drink plenty of fluids whenever working in fields.

Skin diseases

Long-term exposure to the sun can lead to premature ageing of the skin and increased likelihood of skin cancers. Persons exposed to the direct rays of the sun should wear clothing or sun-screen products to provide protection. At lower latitudes, even a few minutes of exposure to the sun can result in a severe sunburn, especially in those with fair complexions.

Skin cancers can begin on any part of the body, and suspected cancers should immediately be checked by a physician. Some of the frequent signs of skin cancers or pre-cancerous lesions are changes in a mole or birthmark, an irregular border, bleeding or a change in colour, often to a brown or gray tone. Those with a history of sun exposure should undergo annual skin cancer screenings.

Contact dermatitis and other allergies

Frequent and prolonged contact with plant excretions or plant pieces can result in sensitization and cases of contact allergies and dermatitis. Prevention through wearing long-sleeved shirts, long-legged pants and gloves whenever possible is the preferred course of action. Some creams can be used to provide a barrier to the transfer of irritants to the skin. If the skin cannot be protected from exposure to plants, washing immediately after the plant contact ends will minimize the effects. Cases of dermatitis with skin eruptions or which do not heal should be seen by a physician.

ORCHARD CROPS

Melvin L. Myers

Generally, farms where fruit trees grow in the temperate zones are called orchards; tropical trees are typically grown in plantation or village groves. Naturally occurring fruit trees have been bred and selected over the centuries to produce a diversity of cultivars. Temperate orchard crops include the apple, pear, peach, nectarine, plum, apricot, cherry, persimmon and prune. Nut crops grown in either temperate or semitropical climates include the pecan, almond, walnut, filbert, hazelnut, chestnut and pistachio. Semitropical orchard crops include the orange, grapefruit, tangerine, lime, lemon, figs, kiwis, tangelo, kumquat, calamondin (Panama orange), citron, Javanese pomelo and date.

Orchard Systems

The growing of fruit trees involves several processes. Orchardists may choose to propagate their own stock either by planting seed or asexually through one or more cutting, budding, grafting or tissue culture techniques. Orchardists plow or disk the soil for planting the tree stock, dig holes in the soil, plant the tree and add water and fertilizer.

Growing the tree requires fertilizing, weed control, irrigation and protecting the tree from spring frost. Fertilizer is applied aggressively during the early years of a tree’s growth. Components of fertilizers mixtures used include ammonium nitrate and suphate, elemental fertilizer (nitrogen, phosphorus and potassium), cottonseed meal, blood meal, fish meal, sterilized sewage sludge and urea formaldehyde (slow release). Weeds are controlled by mulching, tilling, mowing, hoeing and applying herbicides. Insecticides and fungicides are applied with sprayers, which are tractor-drawn in the larger operations. Several pests can damage the bark or eat the fruit, including squirrels, rabbits, raccoons, opossums, mice, rats and deer. Controls include netting, live traps, electric fences and guns, as well as visual or odorous deterrents.

Spring freezes can destroy flower blooms in hours. Overhead sprinklers are used to maintain a water-ice mixture so that the temperature does not drop below freezing. Special frost-guard chemicals may be applied with the water to control ice-nucleating bacteria, which can attack damaged tree tissue. Heaters also may be used in the orchard to prevent freezing, and they may be oil-fired in open areas or electric incandescent bulbs under a plastic film supported by plastic pipe frames.

Pruning tools can transmit disease, so they are soaked in a water-chlorine bleach solution or rubbing alcohol after pruning each tree. All limbs and trimmings are removed, shredded and composted. Limbs are trained, which requires the positioning of scaffolds between limbs, building trellises, pounding vertical stakes into the soil and tying limbs to these devises.

The honey-bee is the principal pollinator of fruit trees. Partial girdling—knife cuts into the bark on each side of the trunk—of the peach and pear tree can stimulate production. To avoid excess stunting, limb breakage and irregular bearing, orchardists thin the fruit either by hand or chemically. The insecticide carbaryl (Sevin), a photo inhibitor, is used for chemical thinning.

Manual fruit picking requires climbing ladders, reaching for the fruit or nuts, placing the fruit into containers and carrying the filled container down the ladder and to a collection area. Pecans are knocked from the trees with long poles and gathered manually or by a special machine that envelopes and shakes the tree trunk and catches and automatically funnels the pecans into a container. Trucks and trailers are commonly used in the field during harvest and for transport on public roads.

Tree Crop Hazards

Orchardists use a variety of agricultural chemicals, including fertilizers, herbicides, insecticides and fungicides. Pesticide exposures occur during application, from residues during various tasks, from pesticide drift, during mixing and loading and during harvesting. Employees may also be exposed to noise, diesel exhaust, solvents, fuels and oils. Malignant melanoma is elevated for orchardists as well, especially to the trunk, scalp and arms, presumably from sunlight (ultraviolet exposure). Handling some types of fruit, especially citrus, may cause allergies or other skin problems.

Rotary mowers are popular machines for cutting weeds. These mowers are attached to and powered by tractors. Riders on tractors can fall off and be seriously injured or killed by the mower, and debris can be thrown hundreds of metres and cause injury. 

The construction of fences, trellises and vertical stakes in orchards may require the use of tractor-mounted post hole diggers or post drivers. Post hole diggers are tractor-powered augers that drill holes 15 to 30 cm in diameter. Post drivers are tractor-power impact drivers for pounding posts into the soil. Both of these machines are dangerous if not operated properly.

Dry fertilizer can cause skin burns and irritation of the mouth, nose and eyes. The spinning mechanism at the rear of a centrifugal broadcast spreader is also a source of injury. Spreaders are also cleaned with diesel fuel, which presents a fire hazard.

Fatalities among orchard workers may occur from motor vehicle crashes, tractor rollovers, farm machinery incidents and electrocutions from moving irrigation pipe or ladders that come into contact with overhead power lines. For orchard work, rollover protective structures (ROPs) are commonly removed from tractors because of their interference with tree limbs.

Manual handling of fruit and nuts in the picking and carrying operations places orchardists at  risk of sprain and strain injury. In addition, hand tools such as knives and shears are hazards for cuts in orchard work. Orchardists are also exposed to falling objects from the trees during harvesting and injury from falls from ladders.

Hazard Control

In the use of pesticides, the pest must be identified first so that the most effective control method and timing of control can be used. Safety procedures on the label should be followed, including the use of personal protective equipment. Heat stress is a hazard when wearing protective gear, so frequent rest breaks and plenty of drinking water are needed. Attention needs to be given to allowing enough reentry time to prevent hazardous exposures from pesticide residue, and pesticide drift from applications elsewhere in the orchard needs to be avoided. Good sanitary facilities are needed, and gloves may be useful to avoid skin disorders. In addition, table 64.8  shows several safety precautions in operating rotary mowers, post hole diggers, post drivers and fertilizer spreading.

Table 64.8 Safety precautions for rotary mowers, post hole diggers and post drivers

Rotary mowers (cutters)

  • Avoid cutting over tree stumps, metal, and rocks, which can become projectiles thrown from the mower.
  • Keep people out of the work area to avoid being struck by flying objects.
  • Maintain the chain guards around the mower to prevent projectiles from being thrown from the mower.
  • Do not allow riders on the tractor to avoid a fall under the mower.
  • Keep PTO shields in place.
  • Disengage the PTO before starting the tractor.
  • Use care when turning sharp corners and pulling drawn mowers so as not to catch the mower on the tractor wheel, which can result in the mower being thrown towards the operator.
  • Use front wheel weights when attached to a mower by the three-point hitch so as to keep the front wheels on the round to maintain steering control.
  • Use wide-set tires if possible to add to tractor stability.
  • Lower the mower to the ground before leaving it unattended.

Post hole diggers (tractor mounted augers)

  • Shift the transmission into park or neutral before operation.
  • Set tractor brakes before digging.
  • Run the digger slowly to maintain control.
  • Dig the hole in small steps.
  • Never wear loose hair, clothing, or drawstrings when digging.
  • Keep everyone clear of the auger and power shafts when digging.
  • Stop the auger and lower it to the ground when not digging.
  • Do not engage the power when unlodging an auger. Remove lodged augers manually by turning it counter clockwise and then hydraulically lift the auger with the tractor.

Post drivers (tractor mounted, impact driver)

  • Shut off the tractor engine and lower the hammer before lubrication or adjustment.
  • Never place hands between the top of the post and the hammer.
  • Do not exceed the recommended hammer stroke per minute.
  • Use a guide to hold the post during driving in case the post breaks.
  • Keep hands clear of posts that are about to be driven.
  • Put all shields in place before operation.
  • Wear safety glasses and hearing protection during operation.

Fertilizer spreading (mechanical)

  • Stay clear of the rear of fertilizer spreaders.
  • Do not unplug a spreader while it is operating.
  • Work in well-ventilated areas away from fire ignition sources when cleaning the spreaders with diesel fuel.
  • Keep the dust off of skin, wear long sleeved shirts, and button collar when handling dry fertilizer. Wash several times a day.
  • Work with the wind blowing away from work.
  • Tractor operators should drive crosswind to the spreader to avoid dust blowing onto them.

Where ROPs interfere with orchard work, foldable or telescoping ROPs should be installed. The operator should not be belted into the seat when operating without a deployed ROPs. As soon as overhead clearance permits, the ROPs should be deployed and the seat belt fastened.

To prevent falls, use of the top step of the ladder should be prohibited, the ladder rungs should have anti-slip surfaces and workers should be trained and oriented on proper ladder use at the beginning of their employment. Non-conductive ladders or ladders with insulators designed into them should be used to avoid possible electrical shock if they contact a power line.

TROPICAL TREE AND PALM CROPS

Melvin L. Myers*

*Some text was revised from the articles “Date palms”, by D. Abed; “Raffia” and “Sisal”, by E. Arreguin Velez; “Copra”, by A.P. Bulengo; “Kapok”, by U. Egtasaeng; “Coconut cultivation”, by L.V.R. Fernando; “Bananas”, by Y. Ko; “Coir”, by P.V.C. Pinnagoda; and “Oil palms”, by G.O. Sofoluwe from the 3rd edition of this “Encyclopaedia”.

Although archaeological evidence is inconclusive, tropical forest trees transplanted to the village may have been the first domesticated agricultural crops. More than 200 fruit tree species have been identified in the humid tropics. Several of these trees and palms, such as the banana and coconut, are cultivated in smallholdings, cooperatives or plantations. While the date palm is completely domesticated, other species, such as the Brazil nut, are still harvested in the wild. More than 150 varieties of bananas and 2,500 palm species exist around the world, and they provide a broad range of products for human use. Sago palm wood feeds millions of people around the world. The coconut palm is used in more than 1,000 ways and the palmyra palm in more than 800 ways. About 400,000 people depend on the coconut for their entire livelihood. Several trees, fruits and palms of the tropical and semitropical zones of the world are listed in table 64.9, and table 64.10  shows selected commercial palms or palm types and their products.

Table 64.9 Commercial tropical and subtropical trees, fruits and palms

Categories

Species

Tropical and semitropical fruits (excluding citrus)

Figs, banana, jelly palm, loquat, papaya, guava, mango, kiwis, date, cherimoya, white sapota, durian, breadfruit, Surinam cherry, lychee, olive, carambola, carob, chocolate, loquat, avocado, sapodilla, japoticaba, pomegranate, pineapple

Semitropical citrus fruits

Orange, grapefruit, lime, lemon, tangerine, tangelos, calamondins, kumquats, citrons

Tropical nut trees

Cashew, Brazil, almond, pine, and macadamia nuts

Oil crops

Oil palm, olive, coconut

Insect feed

Mulberry leaf (silkworm feed), decaying sago palm pith (grub feed)

Fibre crops

Kapok, sisal, hemp, coir (coconut husk), raffia palm, piassaba palm, palmyra palm, fishtail palm

Starch

Sago palm

Vanilla bean

Vanilla orchid

Table 64.10 Palm products

Groups

Products

Uses

Coconut

Nut meat

Food, copra, animal feed

 

Copra (desiccated meat)

Food, oil, oilsoap, candle, cooking oil, margarine, cosmetics, detergent, pai, coconut milk, cream, jam

 

Nut water

Fuel, charcoal, bowls, scoops, cups

 

Nut shells

Mats, string, potting soil mix, brush, rope, cordage

 

Coir (husk)

Thatching, weaving

 

Leaves

Building

 

Wood

Palm honey

 

Flower nectar inflorescence

Palm sugar, alcohol, arrack (palm spirits)

Date

Fruit

Dry, sweet and fine dates

 

Sap

Date sugar

African oil

Fruit (palm pulp oil; similar to olive oil)

Cosmetics, margarine, dressing, fuel, lubricants

 

Seeds (palm kernel oil)

Soap, glycerine

Palmyra

Leaves

Paper, shelter, weaving, fans, buckets, caps

 

Petioles and leaf sheaths

Carpets, rope, twine, brooms, brushes

   

Timber, sago, cabbage

 

Truck

Food, fruit pulp, starch, buttons

 

Fruit and seeds

Sugar, wine, alcohol, vinegar, sura (raw sap drink)

 

Sap, roots

Food, diuretic

Sago (trunk pith of various species)

Starch

Meals, gruels, puddings, bread, flour

 

Insect feed

Food (grubs feeding on decayed sago pith)

Cabbage (various species)

Apical bud (upper trunk)

Salads, canned palm hearts or palmito

Raffia

Leaves

Plaiting, baskets work, tying material

Sugar (various species)

Palm sap

Palm sugar (gur, jaggery)

Wax

Leaves

Candles, lipsticks, shoe polish, car polish, floor wax

Rattan cane

Stems

Furniture

Betel nut

Fruit (nut)

Stimulant (betel chewing)

Processes

The agriculture of tropical tree and palm growing includes propagation, cultivation, harvesting and post-harvesting processes.

Propagation of tropical trees and palms can be sexual or asexual. Sexual techniques are needed to produce fruit; pollination is critical. The date palm is doecious, and pollen from the male palm must be dispersed upon the female flowers. Pollination is done either by hand or mechanically. The manual process involves the workers climbing the tree by gripping the truck or using tall ladders to hand pollinate the female trees by placing small male clusters in the center of each female cluster. The mechanical process uses a powerful sprayer to carry the pollen over the female clusters. In addition to use for generating products, sexual techniques are used to produce seed, which is planted and cultivated into new plants. An example of an asexual technique is cutting shoots from mature plants for replanting.

Cultivation can be manual or mechanized. Banana cultivation is typically manual, but in flat terrain, mechanization with large tractors is used. Mechanical shovels may be used to dig drainage ditches in banana fields. Fertilizer is added monthly to bananas, and pesticides are applied with boom sprayers or from the air. The plants are supported with bamboo poles against storm damage. A banana plant bears fruit after two years.

Harvesting relies largely on manual labour, though some machinery is also used. Harvesters cut the banana bunches, called hands, from the tree with a knife attached to a long pole. The bunch is dropped onto a worker’s shoulder and a second worker attaches a nylon cord to the bunch, which is then attached to an overhead cable that moves the bunch to a tractor and trailer for transport. Tapping the coconut inflorescence for the juice entails the taper walking from tree to tree on strands of rope high above the ground. Workers climb to the tree tops to pluck the nuts manually or cut the nuts with a knife attached to long bamboo poles. In the Southwest Pacific area the nuts are allowed to fall naturally; then they are gathered. The date ripens in the fall and two or three crops are gathered, requiring climbing the tree or a ladder to the date clusters. An old system of machete harvesting of fruit bunches has been replaced by the use of a hook and pole. However, the machete is still used in harvesting many crops (e.g., sisal leaves).

Post-harvest operations vary between tree and palm and by the expected product. After harvesting, banana workers—typically women and youth—wash the bananas, wrap them in polyethylene and pack them in corrugated cardboard boxes for shipping. Sisal leaves are dried, bound and transported to the factory. Kapok fruit is field dried, and the resulting brittle fruit is broken open with a hammer or pipe. Kapok fibers are then ginned in the field to remove seeds by shaking or stirring, packed in jute sacks, batted in sacks to soften the fibers and baled. After harvest, dates are hydrated and artificially ripened. They are exposed to hot air (100 to 110 °C) to glaze the skin and semi-pasteurize them and then packaged.

The dried meaty endosperm of the coconut is marketed as copra, and the prepared husk of the coconut is marketed as coir. The fibrous nut husks are stripped off by striking and levering them against spikes firmly fixed into the ground. The nut, stripped of the husk, is split in half with an axe and dried either in the sun, kilns or hot-air dryers. After drying, the meat is separated from the hard woody shell. Copra is used to produce coconut oil, oil extraction residue called copra cake or poonac and desiccated food. The coir is retted (partially rotted) by soaking in water for three to four weeks. Workers remove the retted coir from the pits in waist-deep water and send it for decortication, bleaching and processing.

Hazards and Their Prevention

Hazards in tropical fruit and palm crop production include injuries, natural exposures, pesticide exposures and respiratory and dermatitis problems. Working at high elevations is required for much work with many tropical trees and palms. The popular apple banana grows to 5 m, kapok to 15 m, coconut palms to 20 to 30 m, evergreen date palm to 30 m, and the oil palm, 12 m. Falls represent one of the most serious hazards in tropical tree cultivation, and so do falling objects. Safety harnesses and head protection should be used, and workers should be trained in their use. Using dwarf varieties of the palms may help eliminate the tree falls. Falls from the kapok tree because of branches breaking and minor hand injuries during shell cracking are also hazards.

Workers can be injured during the transport on trucks or tractor-drawn trailers. Workers climbing palms receive cuts and abrasions of the hands due to contact with sharp date palm spines and oil palm fruit as well as spiny sisal leaves. Sprains from falling in ditches and holes are a problem. Severe wounds from the machete may be inflicted. Workers, typically women, who lift packed boxes of bananas are exposed to heavy weights. Tractors should have safety cabs. Workers should be trained in the safe handling of agricultural implements, machinery guarding and safe tractor operation. Puncture-resistant gloves should be worn, and arm protection and hooks should be used in harvesting the oil palm fruit. Mechanization of weeding and cultivation reduces sprains from falls in ditches and holes. Safe and proper work practices should be used, such as proper lifting, getting help when lifting to reduce individual loads and taking breaks.

Natural hazards include snakes—a problem during forest clearing and in newly established plantations—and insects as well as diseases. Health problems include malaria, ancylostomiasis, anaemia and enteric diseases. The retting operation exposes workers to parasites and skin infections. Mosquito control, sanitation and safe drinking water are important.

Pesticide poisoning is a hazard in tropical tree production, and pesticides are used in significant quantities in fruit groves. However, palms have few problems with pests, and those that are a problem are unique to specific parts of the life cycle and thus can be identified for specific control. Integrated pest management and, when applying pesticides, following the manufacturer’s instructions are important protective measures.

Medical evaluations have identified cases of bronchial asthma among date workers probably from pollen exposure. Also reported among date workers are chronic dry eczema and “nail disease” (onychia). Respiratory protection should be provided during the pollination process, and workers should wear hand protection and frequently wash their hands to protect their skin when working with the trees and dates.

BARK AND SAP PRODUCTION

Melvin L. Myers*

*Some text was revised from the articles “Hemp”, by A. Barbero-Carnicero; “Cork”, by C. de Abeu; “Rubber cultivation”, by the Dunlop Co.; “Turpentine”, by W. Grimm and H. Gries; “Tanning and leather finishing”, by V.P. Gupta; “Spice industry”, by S. Hruby; “Camphor”, by Y. Ko; “Resins”, by J. Kubota; “Jute”, by K.M. Myunt; and “Bark”, by F.J. Wenzel from the 3rd edition of this “Encyclopaedia”.

The term bark refers to the multilayered protective shell covering a tree, shrub or vine. Some herbaceous plants, such as hemp, are also harvested for their bark. Bark is composed of inner and outer bark. Bark starts at the vascular cambium in the inner bark, where cells are generated for the phloem or conductive tissue that transports sugar from the leaves to the roots and other parts of the plant and the sap wood inside the bark layer with vessels that carry water (sap) up from the roots to the plant. The primary purpose of the outer bark is to protect the tree from injury, heat, wind and infection. A great variety of products are extracted from bark and tree sap, as shown in table 64.11 .

Table 64.11 Bark and sap products and uses

Commodity

Product (tree)

Use

Resins (inner bark)

Pine resin, copal, frankincense, myrrh, red resin (climbing palm)

Varnish, shellac, lacquer

   

Incense, perfume, dye

Oleoresins (sapwood)

Turpentine

Solvent, thinner, perfume feedstock, disinfectant, pesticide

 

Rosin

Violin bow treatment, varnish, paint, sealing wax, adhesive, cement, soap

 

Benzoin

Gymnast’s powder

 

Camphor (camphor laurel tree)

Perfume, incense, plastic and film feedstock, lacquers, smokeless powder explosives, perfumes, disinfectants, insect repellents

Latex

Rubber

Tyres, balloons, gaskets, condoms, gloves

 

Gutta-percha

Insulators, underground and marine cable coatings, golf balls, surgical appliances, some adhesives, chicle/base for chewing gum

Medicines and poisons (bark)

Witch hazel

Lotions

 

Cascara

Emetic

 

Quinine (cinchona)

Anti-malaria medicinal

 

Cherry

Cough medicine

 

Pacific yew

Ovarian cancer treatment

 

Curarine

Arrow poison

 

Caffeine (yoco vine)

Amazonian soft drink

 

Lonchocarpus vine

Fish asphyxiate

Flavours (bark)

Cinnamon (cassia tree)

Spice, flavouring

 

Bitters, nutmeg and mace, cloves, sassafras root

Root beer (until linked to liver cancer)

Tannins (bark)

Hemlock, oak, acacia, wattle, willow, mangrove, mimosa, quebracho, sumach, birch

Vegetable tanning for heavier leathers, food processing, fruit ripening, beverage (tea, coffee, wine) processing, ink colouring ingredient, dyeing mordants

Cork (outer bark)

Natural cork (cork oak), reconstituted cork

Buoy, bottle cap, gasket, cork paper, cork board, acoustic tile, shoe inner sole

Fibre (bark)

Cloth (birch, tapa, fig, hibiscus, mulberry)

Canoe, paper, loincloth, skirt, drapery, wall hanging, rope, fishing net, sack, coarse clothing

 

Baobab tree (inner) bark

Hat

 

Jute (linden family)

Hessians, sackings, burlap, twine, carpets, clothing

 

Bast from flax, hemp (mulberry family), ramie (nettle family)

Cordage, linen

Sugar

Sugar maple syrup (sapwood)

Condiment syrup

 

Gur (many palm species)

Palm sugar

Waste bark

Bark chips, strips

Soil conditioner, mulch (chips), garden pathway covering, fiberboard, particleboard, hardboard, chipboard, fuel

Trees are grown for their bark and sap products either by cultivation or in the wild. Reasons for this choice vary. Cork oak groves have advantages over wild trees, which are contaminated by sand and grow irregularly. The control of a rubber tree leaf rust fungus in Brazil is more effective in the sparse tree spacing of the wild. However, in locations free of this fungus, such as in Asia, plantation groves are very effective for cultivating rubber trees.

Processes

Three broad processes are used in harvesting bark and sap: stripping of bark in sheets, debarking for bulk bark and bark ingredients and the extraction of tree fluids by cutting or tapping.

Bark sheets

Stripping sheets of bark from standing trees is easier when the sap is running or after steam injection between the bark and the wood. Two bark stripping technologies are described below, one for cork and the other for cinnamon.

The cork oak is cultivated in the western Mediterranean basin for cork, and Portugal is the largest cork producer. The cork oak, as well as other trees such as the African baobab tree, share the important feature of regrowing outer bark after its removal. Cork is part of the outer bark that lies beneath the hard outer shell called the rhytidome. The thickness of the cork layer increases year-by-year. After an initial bark removal, harvesters cut regrown cork every 6 to 10 years. Stripping the cork involves cutting two circular and one or more vertical cuts without damaging the inner bark. The cork worker uses a bevelled hatchet handle to remove the cork sheets. The cork is then boiled, scraped and cut into marketable sizes.

Cinnamon tree cultivation has spread from Sri Lanka to Indonesia, East Africa and the West Indies. An ancient tree management technique is still used in cinnamon cultivation (as well as willow and cascara tree cultivation). The technique is called coppicing, from the French word couper, meaning to cut. In neolithic times, humans discovered that when a tree is cut close to the ground, a mass of similar, straight branches would sprout from the root around the stump, and that these stems could be regenerated by regular cutting just above ground. The cinnamon tree can grow to 18 m but is maintained as 2-metre-high coppices. The main stem is cut at three years, and the resulting coppices are harvested every two to three years. After cutting and bundling the coppices, the cinnamon gatherers slit the bark sides with a sharp, curved knife. They then strip the bark off and after one to two days separate the outer and inner bark. The outer corky layer is scraped off with a broad, blunt knife and discarded. The inner bark (phloem) is cut into 1-metre lengths called quills; these are the familiar cinnamon sticks.

Bulk bark and ingredients

In the second major process, bark may also be removed from cut trees in large rotating containers called debarking drums. Bark, as a byproduct of lumber, is used as fuel, fibre, mulch or tannin. Tannin is among the most important bark products and is used to produce leather from animal skins and in food processing (see the chapter Leather, fur and footwear). Tannins are derived from a variety of tree barks around the world by open diffusion or percolation.

In addition to tannin, many barks are harvested for their ingredients, which include witch hazel and camphor. Witch hazel is a lotion extracted by steam distillation of twigs from the North American witch hazel tree. Similar processes are used in harvesting camphor from branches of the camphor laurel tree.

Tree fluids

The third major process includes the harvesting of resin and latex from the inner bark and oeloresins and syrup from the sapwood. Resin is found especially in the pine. It oozes out of bark wounds to protect the tree from infection. To commercially obtain resin, the worker must wound the tree by peeling off a thin layer of the bark or piercing it.

Most resins thicken and harden when exposed to the air, but some trees produce liquid resins or oleoresins, such as turpentine from conifers. Severe wounds are made into one side of the tree wood to harvest turpentine. The turpentine runs down the wound and is collected and hauled to storage. Turpentine is distilled into turpentine oil with a colophony or rosin residue.

Any milky sap exuded by plants is called latex, which in rubber trees is formed in the inner bark. Latex gatherers tap the rubber trees with spiral cuts around the trunk without damaging the inner bark. They catch the latex in a bowl (see the chapter Rubber industry). The latex is kept from hardening either through coagulation or with an ammonium hydroxide fixative. Acid wood smoke in the Amazon or formic acid is used to coagulate raw rubber. Crude rubber is then shipped for processing.

In the early spring in the cold climates of the United States, Canada, and Finland, a syrup is harvested from the sugar maple tree. After the sap starts to run, spouts are placed into drilled holes in the trunk through which sap runs either into buckets or through plastic piping for transport to storage tanks. The sap is boiled to 1/40th of its original volume to produce maple syrup. Reverse osmosis may be used to remove much of the water prior to evaporation. The concentrated syrup is cooled and bottled.

Hazards and Their Prevention

The hazards related to producing bark and sap for processing are natural exposures, injuries, pesticide exposures, allergies and dermatitis. Natural hazards include snake and insect bites and the potential for infection where vector-borne or water-borne diseases are endemic. Mosquito control is important on plantations, and pure water supply and sanitation is important at any tree farm, grove or plantation.

Much of the work with bark stripping, cutting and tapping involves the possibility of cuts, which should be promptly treated to prevent infection. Hazards exist in the manual cutting of trees, but mechanized methods of clearing as well as planting have reduced injury hazards. The use of heat for “smoking” rubber and evaporating oils from bark, resins and sap expose workers to burns. Hot maple syrup exposes workers to scalding injuries during boiling. Special hazards include working with draught animals or vehicles, tool-related injuries and the lifting of bark or containers. Bark stripping machines expose workers to potentially serious injury as well as to noise. Injury control techniques are needed, including safe work practices, personal protection and engineering controls.

Pesticide exposures, especially to the herbicide sodium arsenite on rubber plantations, are potentially hazardous. These exposures can be controlled by following manufacturer recommendations for storage, mixing and spraying.

Allergic proteins have been identified in natural rubber sap, which has been associated with latex allergy (Makinen-Kiljunen et al. 1992). Substances in pine resin and sap can cause allergic reactions in persons sensitive to balsam-of-Peru, colophony or turpentine. Resins, terpenes and oils may cause allergic contact dermatitis in workers handling unfinished wood. Dermal exposures to latex, sap and resin should be avoided through safe work practices and protective clothing.

The disease hypersensitivity pneumonitis is also known as “maple stripper’s lung”. It is caused by exposure to the spores of Cryptostroma corticate, a black mould that grows under the bark, during bark removal from stored maple. Progressive pneumonitis may also be associated with sequoia and cork oak woods. Controls include eliminating the sawing operation, wetting the material during debarking with a detergent and ventilation of the debarking area.

BAMBOO AND CANE

Melvin L. Myers and Y.C. Ko*

*Adapted from Y.C. Ko’s article, “Bamboo and cane”, “Encyclopaedia of Occupational Health and Safety”, 3rd edition.

Bamboo, which is a subfamily of the grasses, exists as more than a thousand different species, but only a few species are cultivated in commercial plantations or nurseries. Bamboos are tree-like or shrubby grasses with woody stems, called culms. They range from small plants with centimetre-thick culms to giant subtropical species up to 30 m tall and 30 cm in diameter. Some bamboos grow at a prodigious rate, up to 16 cm in height per day. Bamboos rarely flower (and when they do, it may be at intervals of 120 years), but they can be cultivated by planting their stalks. Most bamboos came from Asia, where they grow wild in tropical and subtropical areas. Some species have been exported to temperate climates, where they require irrigation and special care during the winter.

Some bamboo species are used as vegetables and may be pickled or preserved. Bamboo has been used as an oral medicine against poisoning since it contains silicic acid which absorbs poison in the stomach. (Silicic acid is now produced synthetically.)

The wood-like properties of bamboo culms have led to their use for many other purposes. Bamboo is used in building houses, with the culms as uprights and the walls and roofs made from split stems or lattice work. Bamboo is also used for making boats and boat masts, rafts, fences, furniture, containers and handicraft products, including umbrellas and walking sticks. Other uses abound: water pipes, wheelbarrow axles, flutes, fishing rods, scaffolding, roller-blinds, ropes, rakes, brooms and weapons such as bows and arrows. In addition, bamboo pulp has been used to make high-quality paper. It is also grown in nurseries and used in gardens as ornamentals, wind breaks and hedges (Recht and Wetterwald 1992).

Cane is sometimes confused with bamboo, but is botanically different and comes from varieties of the rattan palm. Rattan palms grow freely in tropical and subtropical areas, particularly in Southeast Asia. Cane is used to make furniture (especially chairs), baskets, containers and other handicraft products. It is very popular due to its appearance and elasticity. It is frequently necessary to split the stems when cane is used in manufacturing.

Cultivation Processes

The processes for cultivating bamboo include propagation, planting, watering and feeding, pruning and harvesting. Bamboos are propagated in two ways: by planting seeds or by using sections of the rhizome (the underground stem). Some plantations depend upon natural reseeding. Since some bamboos flower infrequently and seeds remain viable only for a couple of weeks, most propagation is accomplished by dividing a large plant that includes the rhizome with culms. Spades, knives, axes or saws are used to divide the plant.

Growers plant bamboo in groves, and planting and replanting bamboo involves digging a hole, placing the plant into the hole and backfilling soil around its rhizomes and roots. About 10 years is required to establish a healthy grove of bamboo. Although not a concern in its native habitat where it rains often, irrigation is necessary when bamboos are grown in drier areas. Bamboo requires a lot of fertilizer, particularly nitrogen. Both animal dung and commercial fertilizer are used. Silica (SiO2) is as important for bamboos as is nitrogen. In natural growth, bamboo gains enough silica naturally by recycling it from shed leaves. In commercial nurseries, shed leaves are left around the bamboo and silica-rich clay minerals such as Bentonite may be added. Bamboos are pruned of old and dead culms to provide room for new growth. In Asian groves, dead culms may be split in the fields to hasten their decay and add to the soil’s humus.

Bamboo is harvested either as a food or for its wood or pulp. Bamboo shoots are harvested for food. They are dug from the soil and cut with a knife or chopped with an axe. The bamboo culms are harvested when they are 3 to 5 years old. Harvesting is timed for when the culms are neither too soft nor too hard. Bamboo culms are harvested for their wood. They are cut or chopped with a knife or an axe, and the cut bamboo may be heated to bend it or split with a knife and mallet, depending upon its end use.

Rattan palm cane is usually harvested from wild trees often in uncultivated mountainous areas. The stems of the plants are cut near the roots, dragged out from thickets and sun-dried. The leaves and the bark are then removed, and the stems are sent for processing.

Hazards and Their Prevention

Venomous snakes present a hazard in plantation groves. Stumbling over bamboo stumps may cause falls, and cuts can lead to tetanus infection. Bird and chicken droppings in bamboo groves can be contaminated with Histoplasma capsulatum (Storch et al. 1980). Working with bamboo culms can lead to knife cuts, particularly when splitting the culms. Sharp edges and the ends of bamboos can cause cuts or punctures. Hyperkeratosis of the palms and fingers has been observed in workers who make bamboo containers. Pesticide exposures are also possible. First aid and medical treatment is required to deal with snake bites. Vaccine and booster vaccine should be used to prevent tetanus.

All cutting knives and saws should be maintained and used with care. Where bird droppings are present, work should be conducted during wet conditions to prevent dust exposure, or  respiratory protection should be used.

In harvesting palm cane, workers are exposed to the dangers of remote forests, including snakes and venomous insects. The bark of the tree has thorns that may tear the skin, and workers are exposed to cuts from knives. Gloves should be worn when the stems are handled. Cuts are also a risk during manufacture, and hyperkeratosis of the palms and fingers may often occur among workers, probably because of the friction of the material.

TOBACCO CULTIVATION

Gerald F. Peedin

Tobacco (Nicotiana tabacum) is a unique plant with its characteristic commercial component, nicotine, contained in its leaves. Although cotton is grown on more surface area, tobacco is the most widely grown nonfood crop in the world; it is produced in approximately 100 countries and on every continent. Tobacco is consumed around the world as cigarettes, cigars, chewing or smoking tobaccos and snuff. However, over 80% of world production is consumed as cigarettes, currently estimated at nearly 5.6 trillion annually. China, the United States, Brazil and India produced over 60% of total world production in 1995, which was estimated at 6.8 million tonnes.

The specific uses of tobacco by manufacturers are determined by the chemical and physical properties of the cured leaves, which in turn are determined by interactions among genetic, soil, climatic and cultural management factors. Therefore, many kinds of tobacco are grown in the world, some with rather specific local, commercial uses in one or more tobacco products. In the United States alone, tobacco is categorized into seven major classes which contain a total of 25 different tobacco types. The specific techniques used to produce tobacco vary among and within tobacco classes in various countries, but cultural manipulation of nitrogen fertilization, plant density, time and height of topping, harvesting and curing are used to favourably influence the usability of the cured leaves for specific products; quality of leaves, however, is highly dependent on prevailing environmental conditions.

Flue-cured, Burley and Oriental tobaccos are the major components of the increasingly popular blended cigarette now consumed worldwide, and represented 57, 11 and 12%, respectively, of world production in 1995. Thus, these tobaccos are widely traded internationally; the United States and Brazil are the major exporters of flue-cured and Burley leaf tobaccos, while Turkey and Greece are the major world suppliers of Oriental tobacco. The world’s largest tobacco producer and cigarette manufacturer, China, currently consumes most of its production internally. Because of increasing demand for the “American” blended cigarette, the United States became the major cigarette exporter in the early 1990s.

Tobacco is a transplanted crop. In most countries, seedlings are started from tiny seeds (about 12,000 per gram) sown by hand on well-prepared soil beds and manually removed for transplanting to the field after reaching a height of 15 to 20 cm. In tropical climates, seed-beds are usually covered with dried plant materials to preserve soil moisture and reduce disturbance of seeds or seedlings by heavy rains. In cooler climates, seed-beds are covered for frost and freeze protection with one of several synthetic materials or with cotton cheesecloth until several days before transplanting. The bed sites are usually treated before seeding with methyl bromide or dazomet to manage most weeds and soil-borne diseases and insects. Herbicides for supplemental grass management are also labelled for use in some countries, but in areas where labour is plentiful and inexpensive, weeds and grasses are often removed by hand. Foliar insects and diseases are usually managed with periodic applications of appropriate pesticides. In the United States and Canada, seedlings are produced primarily in greenhouses covered with plastic and glass, respectively. Seedlings are usually grown in peat- or muck-based media which, in Canada, are steam-sterilized before seeds are sown. In the United States, polystyrene trays are predominantly used to contain the media and are often treated with methyl bromide and/or a chlorine bleach solution between transplant production seasons to protect against fungal diseases. However, only a few pesticides are labelled in the United States for use in tobacco greenhouses, so farmers there depend substantially on proper ventilation, horizontal air movement and sanitation to manage most foliar diseases.

Regardless of the method of transplant production, seedlings are periodically clipped or mowed above the apical meristems for several weeks before transplanting to improve uniformity and survival after transplanting to the field. Clipping is performed mechanically in some developed countries but manually where labour is plentiful (see figure 64.28).

Figure 64.28 Manual clipping of tobacco seedlings with shears in Zimbabwe

Gerald Peedin

Depending on availability and cost of labour and equipment, seedlings are manually or mechanically transplanted to well- prepared fields previously treated with one or more pesticides for control of soil pathogens and/or grasses (see figure 64.29). In order to protect workers from pesticide exposure, pesticides are seldom applied during the transplanting operation, but additional weed and foliar pest management are often needed during subsequent growth and harvesting of the crop. In many countries, varietal tolerance and 2- to 4-year rotations of tobacco with nonhost crops (where sufficient land is available) are widely used to reduce reliance on pesticides. In Zimbabwe, government regulations require seedling beds and stalks/roots in harvested fields to be destroyed by certain dates to reduce the incidence and spread of insect-transmitted viruses.

Figure 64.29 Mechanical transplanting of flue-cured tobacco in North Carolina (US)

About 4 to 5 hectares per day can be transplanted using ten workers  and a four-row transplanter. Six workers are needed for a two-row transplanter  and four workers for a one-row transplanter.

Gerald Peedin

Depending upon tobacco type, fields receive relatively moderate-to-high rates of fertilizer nutrients, which are usually applied by hand in developing countries. For proper ripening and curing of flue-cured tobacco, it is necessary for nitrogen absorption to decrease rapidly soon after vegetative growth is complete. Therefore, animal manures are not routinely applied to flue-cured soils, and only 35 to 70 kg per hectare of inorganic nitrogen from commercial fertilizers are applied, depending on soil characteristics and rainfall. Burley and most chewing and cigar tobaccos are usually grown on more fertile soils than those used for flue-cured tobacco, but receive 3 to 4 times more nitrogen to enhance certain desirable characteristics of these tobaccos.

Tobacco is a flowering plant with a central meristem which suppresses growth of axillary buds (suckers) by hormonal action until the meristem begins to produce flowers. For most tobacco types, removal of flowers (topping) before seed maturation and control of subsequent sucker growth are common cultural practices used to improve yields by diverting more growth resources into leaf production. Flowers are removed manually or mechanically (primarily in the United States) and sucker growth retarded in most countries with applications of contact and/or systemic growth regulators. In the United States, suckercides are applied mechanically on flue-cured tobacco, which has the longest harvest season of the tobacco types produced in that country. In underdeveloped countries, suckercides are often applied manually. However, regardless of the chemicals and application methods used, complete control is seldom achieved, and some hand labour is usually needed to remove suckers not controlled by the suckercides.

Harvesting practices vary substantially among tobacco types. Flue-cured, Oriental and cigar wrapper are the only types whose leaves are consistently harvested (primed) in sequence as they ripen (senesce) from the bottom to the top of the plant. As leaves ripen, their surfaces become textured and yellow as chlorophyll degrades. Several leaves are removed from each plant in each of several passes over the field during a period of 6 to 12 weeks after topping, depending on rainfall, temperature, soil fertility and variety. Other tobacco types such as Burley, Maryland, cigar binder and filler, and fire-cured chewing tobaccos are “stalk cut”, meaning that the entire plant is cut off near ground level when most of the leaves are judged to be ripe. For some air-cured types, the lower leaves are primed while the remainder of the plant is stalk cut. Regardless of tobacco type, harvesting and preparation of the leaves for curing and marketing are the most labour-intensive tasks in tobacco production (see figure 64.30). Harvesting is normally accomplished with manual labour, especially for stalk cutting, which has yet to be totally mechanized (see figure 64.31). Priming of flue-cured tobacco is now highly mechanized in most developed countries, where labour is scarce and expensive. In the United States, about one-half of the flue-cured type is primed with machines, which requires almost complete weed and sucker control to minimize content of these materials in the cured leaves.

Figure 64.30 Preparing Oriental tobacco for air-curing soon after hand harvesting

The small leaves are collected on a string by pushing a needle  through the central vein of each leaf.

Gerald Peedin

Figure 64.31 Hand harvesting of flue-cured tobacco by a small farmer in southern Brazil

Some farmers use small tractors rather than oxen to pull sleds or trailers.  Over 90% of harvesting and other labour is provided by family members,  relatives and/or neighbours.

Gerald Peedin

Proper curing of most tobacco types requires management of temperature and moisture content within the curing structure to regulate the drying rate of green leaves. Flue-curing requires the most sophisticated curing structures because temperature and moisture control follow rather specific schedules, and temperatures reach over 70 °C in the latter stages of curing, which totals only 5 to 8 days. In North America and Western Europe, flue-curing is accomplished primarily in gas- or oil-fired metal (bulk) barns equipped with automatic or semiautomatic temperature- and humidity-control devices. In most other countries, the barn environment is controlled manually and the barns are constructed of wood or bricks and often fired by hand with wood (Brazil) or coal (Zimbabwe). The initial and most important stage of flue-curing is called yellowing, during which chlorophyll is degraded and most carbohydrates are converted to simple sugars, giving cured leaves a characteristic sweet aroma. The leaf cells are then killed with drier and hotter air to stop respiratory losses of sugars. The products of combustion do not contact the leaves. Most other tobacco types are air-cured in barns or sheds without heat, but usually with some means of partial, manual ventilation control. The air-curing process requires 4 to 8 weeks, depending on prevailing environmental conditions and the ability to control humidity within the barn. This longer, gradual process results in cured leaves with low sugar contents. Fire-cured tobacco, used primarily in chewing and snuff products, is basically air-cured but small, open fires using oak or hickory wood are used to periodically “smoke” the leaves to give them a characteristic wood odour and taste and to improve their keeping properties.

The colours of cured leaves and their uniformity within a lot of tobacco are important characteristics used by buyers to determine the usefulness of tobaccos for specific products. Therefore, leaves with undesirable colours (particularly green, black and brown) are usually manually removed by farmers before offering the tobacco for sale (see figure 64.32).

Figure 64.32 Manual removal of cured Burley leaves from the stalks

Gerald Peedin

In most countries, the cured tobaccos are further separated into homogeneous lots based on variations in leaf colour, size, texture and other visual characteristics (see figure 64.33).

Figure 64.33 Manual separation of cured flue-cured tobacco  into homogeneous grades in Zimbabwe.

Gerald Peedin

In some southern African countries, where labour is plentiful and inexpensive and most of the production is exported, a crop may be sorted into 60 or more lots (i.e., grades) before being sold (as in figure 64.33). Most tobacco types are packaged in bales weighing 50 to 60 kg (100 kg in Zimbabwe) and deliveredto the purchaser in the cured form (see figure 64.34).

Figure 64.34 Loading tobacco bales for transport from the farm  to a marketing centre in southern Brazil.

Gerald Peedin

In the United States, flue-cured tobacco is marketed in burlap sheets averaging about 100 kg each; however, use of bales weighing over 200 kg is currently being evaluated. In most countries, tobacco is produced and sold under contract between the farmer and the purchaser, with predetermined prices for the various grades. In a few large tobacco-producing countries, annual production is controlled by government regulation or by farmer-buyer negotiation, and the tobacco is sold in an auction system with (United States and Canada) or without (Zimbabwe) minimum established prices for the various grades. In the United States, flue-cured or Burley tobacco not sold to commercial buyers is purchased for price support by grower-owned cooperatives and sold later to domestic and foreign buyers. Although some marketing systems have been substantially mechanized, such as that in Zimbabwe (shown in figure 64.35),.a great deal of manual labour is still required to unload and present the tobacco for sale, remove it from the sale area and load and transport it to the buyer’s processing facilities.

Figure 64.35 Unloading a farmer’s tobacco bales at the auction centre in Zimbabwe,  which has the most mechanized and efficient flue-cured marketing system in the world.

Gerald Peedin

Hazards and Their Prevention

The manual labour required to produce and market tobacco varies greatly around the world, depending primarily on the level of mechanization used for transplanting, harvesting and market preparation. Manual labour involves risks of musculoskeletal problems from activities such as transplanting seedlings, application of suckercides, harvesting, separation of the cured tobacco into grades and lifting of tobacco bales. Training in proper lifting methods and provision of ergonomically designed tools can help prevent these problems. Knife injuries may occur during cutting, and tetanus may arise in open wounds. Sharp, well-designed knives and training in their use can reduce the number of injuries.

Mechanization can reduce these risks, but carries risks of injury from the machinery used, including transportation accidents. Well-designed tractors with safety cabs, properly guarded machinery and adequate training can reduce the number of injuries.

Spraying of pesticides and fungicides can involve the risk of chemical exposures. In the United States, the Environmental Protection Administration (EPA) Worker Protection Standard requires farmers to protect workers from pesticide-related illness or injury by (1) providing training on pesticide safety, specifically those pesticides used on the farm; (2) providing personal protective equipment (PPE) and clothing and assuming responsibility for their proper use and cleaning, plus ensuring that workers do not enter treated fields during specific time intervals after pesticide application; and (3) providing decontamination sites and emergency assistance in case of exposure. Substitution of less hazardous pesticides should also be done where possible.

Field labourers, usually those not accustomed to working in tobacco fields, sometimes become nauseous and/or dizzy soon after direct contact with green tobacco during harvesting, perhaps because nicotine or other substances are absorbed through the skin. In the United States, the condition is called “green tobacco sickness” and affects a small percentage of workers. Symptoms occur most often when sensitive individuals are harvesting wet tobacco and their clothing and/or exposed skin is in almost continuous contact with green tobacco. The condition is temporary and not known to be serious, but causes some discomfort for several hours after exposure. Suggestions for sensitive workers to minimize exposure during harvesting or other tasks requiring prolonged contact with green tobacco include not starting work until the leaves have dried or wearing lightweight rain gear and waterproof gloves when the leaves are wet; wearing long trousers, long-sleeve shirts and possibly gloves as precautions when working in dry tobacco; and leaving the field and washing immediately if symptoms occur.

Skin diseases may occur in workers handling tobacco leaf in warehouses or barns. Sometimes workers in these storage areas, especially new workers, may develop conjunctivitis and laryngitis.

Other preventive measures include good washing and other sanitary facilities, provision of first aid and medical care, and proper training.

GINSENG, MINT AND OTHER HERBS

Larry J. Chapman

There is no standard definition for the term herb, and the distinction between the herbs and spice plants is unclear. This article provides an overview of general aspects of some herbs. There are more than 200 herbs, which we are here considering to be those plants originally grown mainly in temperate or Mediterranean climates for their leaves, stems and flowering tops. The primary use for herbs is to flavour foods. Important culinary herbs include basil, bay or laurel leaf, celery seed, chervil, dill, marjoram, mint, oregano, parsley, rosemary, sage, savory, tarragon and thyme. The major demand for culinary herbs comes from the retail sector, followed by the food processing and food service sectors. The United States is by far the major consumer of culinary herbs, followed by the United Kingdom, Italy, Canada, France and Japan. Herbs are also used in cosmetics and pharmaceutical products to impart desirable flavours and odours. Herbs are used medicinally by the pharmaceutical industry and in the practice of herbal medicine.

Ginseng

Ginseng root is used in the practice of herbal medicine. China, the Republic of Korea and the United States are major producers. In China, most operations have historically been plantations owned and run by the government. In the Republic of Korea, the industry is made up of more than 20,000 family operations, most of which are smallholdings, family operations that plant less than an acre each year. In the United States, the largest proportion of producers work on smallholdings and plant less than two acres per year. However, the largest proportion of the US crop is produced by a minority of growers with a hired workforce and mechanization that allows them to plant as much as 60 acres per year. Ginseng is usually grown in open field plots covered by artificial shade structures that simulate the effects of the forest canopy.

Ginseng is also grown in intensively cultivated forest plots. A few per cent of the world’s production (and most organic ginseng) is gathered by wild collectors. The roots take 5 to 9 years to reach marketable size. In the United States, bed preparation for either forest plot or open field methods is typically accomplished by a tractor-towed plow. Some hand labour may be required to clear ditches and give the beds their final shape. Mechanized planters pulled behind a tractor are often used for seeding, although the more labour-intensive practice of transplanting nursery seedlings into beds is common in the Republic of Korea and China. Constructing the 7- to 8-foot-high pole and wood lath or cloth shade structures over open field plots is labour intensive and involves considerable lifting and overhead work. In Asia, locally available woods and thatch or woven reeds are used in the shade structures. In mechanized operations in the United States, mulching the plants is accomplished with straw shredders which are adapted from machines used in the strawberry industry and pulled behind a tractor.

Depending on the adequacy and condition of machine guarding, contact with the tractor PTO shaft, the straw shredder’s intake or other moving machinery parts can present a risk of entanglement injury. For each year until harvest, three hand weedings are required, which involve crawling, bending and stooping to work at crop level and which place high demands on the musculoskeletal system. Weeding, especially for the first- and second-year plants, is intensive work. One acre of field-grown ginseng may require more than 3,000 total hours of weeding over the 5 to 9 years preceding harvest. New chemical and non-chemical weed control methods, including better mulching, may be able to reduce the musculoskeletal demands posed by weeding. New tools and mechanization also hold promise for reducing the demands of weeding work. In Wisconsin, US, some herb growers are testing an adapted pedal cycle that allows weeding in a seated posture.

Artificial shade creates an especially humid environment susceptible to fungus and mould infestation. Fungicides are routinely applied at least monthly in the United States with tractor-towed application machinery or backpack garden sprayers. Insecticides are also spray applied as needed, and rodenticides put out. The use of lower-toxicity chemicals, improvements in application machinery and alternative pest management practices are strategies for reducing the repeated, low-dose pesticide exposures experienced by employees.

When the roots are ready for harvest, the shade structures are disassembled and stored. Mechanized operations utilize digging machinery adapted from the potato industry which is towed behind a tractor. Here again, inadequate machine guarding of the tractor PTO and moving machinery parts may present a risk of entanglement injuries. Picking, the last step in harvesting, involves hand labour and bending and stooping to gather roots from the soil surface.

On smaller holdings in the United States, China and the Republic of Korea, most or all of the steps in the production process are typically done by hand.

Mint and Other Herbs

There is considerable diversity in herb production methods, geographical locations, work methods and hazards. Herbs can be collected in the wild or grown under cultivation. Cultivated plant production has the advantages of greater efficiency, more consistent quality and timing of the harvest, and the potential for mechanization. Much of the mint and other herb production in the United States is highly mechanized. Soil preparation, planting, cultivation, pest control and harvesting are all done from the seat of a tractor with towed machinery.

Potential hazards resemble those in other mechanized crop production and include motor vehicle collisions on public roads, traumatic injuries involving tractors and machinery and agricultural chemical poisonings and burns.

More labour-intensive cultivation methods are typical in Asia, North Africa, the Mediterranean and other areas (e.g., mint production in China, India, the Philippines and Egypt). Plots are ploughed, often with animals, and then beds are prepared and fertilized by hand. Depending on the climate, a network of irrigation trenches is excavated. Depending on the type of herb produced, seeds, cuttings, seedlings or rhizome portions are planted. Periodic weeding is especially labour intensive and the day-long shifts of stooping, bending and pulling place high demands on the musculoskeletal system. Despite extensive use of manual labour, weed control in herb cultivation is sometimes inadequate. For a few crops, chemical weeding with herbicides, sometimes followed by manual weeding, is used, but herbicide use is not widespread since herb crops are often herbicide sensitive. Mulching crops can reduce weeding labour needs as well as conserve soil and soil moisture. Mulching also generally aids plant growth and yield, since mulch adds organic matter to soils as it decomposes.

Aside from weeding, labour-intensive soil preparation methods, planting, construction of shade or support structures, harvesting and other operations can also result in high musculoskeletal demands for prolonged periods. Modifications in production methods, specialized hand tools and techniques, and mechanization are possible directions to explore for reducing musculoskeletal and labour demands.

The potential for pesticide and other agricultural chemical burns and poisonings can be a concern on labour-intensive operations since backpack sprayers and other manual application methods may not prevent adverse exposures via the skin, mucous membranes or breathing air. Work in greenhouse production poses special hazards due to the confined breathing atmosphere. Substituting lower toxicity chemicals and alternative pest management strategies, improving application equipment and application practices, and making better PPE available may be ways to reduce risks.

The extraction of volatile oils from the harvested crop is common for certain herbs (e.g., mint stills). Cut and chopped plant material is loaded into an enclosed wagon or other structure. Boilers produce live steam which is forced into the sealed structure through low-pressure hoses, and the oil is floated and extracted from the resulting vapour.

Possible hazards associated with the process include burns from live steam and, less frequently, boiler explosions. Preventive measures include regular inspections of boilers and live steam lines to ensure structural integrity.

Herb production with low levels of mechanization may require prolonged close contact with plant surfaces and oils and, less often, associated dusts. Some reports are available in the medical literature of sensitization reactions, occupational dermatitis, occupational asthma and other respiratory and immunological problems associated with a number of herbs and spices. The available literature is small and may reflect underreporting rather than a low likelihood of health problems.

Occupational dermatitis has been associated with mint, laurel, parsley, rosemary and thyme, as well as cinnamon, chicory, cloves, garlic, nutmeg and vanilla. Occupational asthma or respiratory symptoms have been associated with dust from Brazilian ginseng and parsley as well as black pepper, cinnamon, cloves, coriander, garlic, ginger, paprika and red chillies (capsaicin), along with bacteria and endotoxins in dusts from grains and herbs. However, most cases have occurred in the processing industry, and only a few of these reports have described problems arising directly from exposures incurred in herb cultivation work (e.g., dermatitis after parsley picking, asthma after chicory root handling, immunologic reactivity after greenhouse work with paprika plants). In most reports, a proportion of the workforce develops problems while other employees are less affected or asymptomatic.

Processing Industry

The herb and spice crop processing industry represents a higher order of magnitude exposure to certain hazards than herb crop cultivation. For example, the grinding, crushing and mixing of leaves, seeds and other plant materials can involve work in noisy, extremely dusty conditions. Hazards in herb processing operations include hearing loss, traumatic injuries from inadequately guarded moving machinery parts, dust exposures in breathing air, and dust explosions. Closed processing systems or enclosures for machinery can reduce noise. Feed openings of grinding machines should not permit the entry of hands or fingers.

Health conditions including skin diseases, irritation of the eyes, mouth and gastrointestinal tract, and respiratory and immunological problems have been linked to dusts, fungi and other air contaminants. Self selection based on ability to tolerate health effects has been noted in spice grinders, usually within the first 2 weeks of work. Segregation of the process, effective local exhaust ventilation, improved dust collection, regular mopping and vacuuming of work areas, and personal protective equipment can help reduce risks from dust explosions and contaminants in breathing air.

MUSHROOMS

L.J.L.D. Van Griensven

The world’s most widely cultivated edible fungi are: the common white button mushroom, Agaricus bisporus, with an annual production in 1991 of approximately 1.6 million tonnes; the oyster mushroom, Pleurotus spp. (about 1 million tonnes); and the shiitake, Lentinus edodes (about 0.6 million tonnes) (Chang 1993). Agaricus is mainly grown in the western hemisphere, whereas oyster mushrooms, shiitake and a number of other fungi of lesser production are mostly produced in East Asia.

The production of Agaricus and the preparation of its substrate, compost, are for a large part strongly mechanized. This is generally not the case for the other edible fungi, although exceptions exist.

The Common Mushroom

The common white button mushroom, Agaricus bisporus, is grown on compost consisting of a fermented mixture of horse manure, wheat straw, poultry manure and gypsum. The materials are wetted, mixed and set in large heaps when fermented outdoors, or brought into special fermentation rooms, called tunnels. Compost is usually made in quantities of up to several hundred tonnes per batch, and large, heavy equipment is used for mixing heaps and for filling and emptying the tunnels. Composting is a biological process that is guided by a temperature regime and that requires thorough mixing of the ingredients. Before being used as a substrate for growth, compost should be pasteurized by heat treatment and conditioned to get rid of the ammonia. During composting, a considerable amount of sulphur-containing organic volatiles evaporates, which can cause odour problems in the surroundings. When tunnels are used, the ammonia in the air can be cleaned by acid washing, and odour escape can be prevented by either biological or chemical oxidation of the air (Gerrits and Van Griensven 1990).

The ammonia-free compost is then spawned (i.e., inoculated with a pure culture of Agaricus growing on sterilized grain). Mycelial growth is carried out during a 2-week incubation at 25 °C in a special room or in a tunnel, after which the grown compost is placed in growing rooms in trays or in shelves (i.e., a scaffold system with 4 to 6 beds or tiers above each other with a distance of 25 to 40 cm in between), covered with a special casing consisting of peat and calcium carbonate. After a further incubation, mushroom production is induced by a temperature change combined with strong ventilation. Mushrooms appear in flushes with weekly intervals. They are either harvested mechanically or hand-picked. After 3 to 6 flushes, the growing room is cooked out (i.e., steam pasteurized), emptied, cleaned and disinfected, and the next growing cycle can be started.

Success in mushroom cultivation depends heavily on cleanliness and prevention of pests and diseases. Although management and farm hygiene are key factors in disease prevention, a number of disinfectants and a limited number of pesticides and fungicides are still used in the industry.

Health Risks

Electrical and mechanical equipment

A pre-eminent risk in mushroom farms is the accidental exposure to electricity. Often high voltage and amperage is used in humid environments. Ground fault circuit interrupters and other electrical precautions are necessary. National labour legislation usually sets rules for the protection of labourers; this should be strictly followed.

Also, mechanical equipment may pose dangerous threats by its damaging weight or function, or by the combination of both. Composting machines with their large moving parts require care and attention to prevent accidents. Equipment used in cultivation and harvesting often has rotating parts used as grabbers or harvesting knives; their use and transport require great care. Again, this holds for all machines that are moving, whether they be self-propelled or pulled over beds, shelves or rows of trays. All such equipment should be properly guarded. All personnel whose duties include handling electrical or mechanical equipment in mushroom farms should be carefully trained before work is started and safety rules should be adhered to. Maintenance ordinances of equipment and machines should be taken very seriously. A proper lockout/tagout programme is needed as well. Lack of maintenance causes mechanical equipment to become extremely dangerous. For example, breaking pull chains have caused several deaths in mushroom farms.

Physical factors

Physical factors such as climate, lighting, noise, muscle load and posture strongly influence the health of workers. The difference between ambient outside temperature and that of a growing room can be considerable, especially in the winter. One should allow the body to adapt to a new temperature with every change of location; not doing so may lead to diseases of the airways and eventually to a susceptibility to bacterial and viral infections. Further, exposure to excessive temperature changes may cause muscles and joints to become stiff and inflamed. This may lead to a stiff neck and back, a painful condition causing unfitness for work.

Insufficient lighting in mushroom-growing rooms not only causes dangerous working conditions but also slows down picking, and it prevents pickers from seeing the possible symptoms of disease in the crop. The lighting intensity should be at least 500 lux.

Muscle load and posture largely determine the weight of labour. Unnatural body positions are often required in manual cultivation and picking tasks due to the limited space in many growing rooms. Those positions may damage joints and cause static overload of the muscles; prolonged static loading of muscles, such as that which occurs during picking, can even cause inflammation of joints and muscles, eventually leading to partial or total loss of function. This can be prevented by regular breaks, physical exercises and ergonomic measures (i.e., adaptation of the actions to the dimensions and possibilities of the human body).

Chemical factors

Chemical factors such as exposure to hazardous substances create possible health risks. The large-scale preparation of compost has a number of processes that can pose lethal risks. Gully pits in which recirculation water and drainage from compost is collected are usually devoid of oxygen, and the water contains high concentrations of hydrogen sulphide and ammonia. A change in acidity (pH) of the water may cause a lethal concentration of hydrogen sulphide to occur in the areas surrounding the pit. Piling wet poultry or horse manure in a closed hall may cause the hall to become an essentially lethal environment, due to the high concentrations of carbon dioxide, hydrogen sulphide and ammonia which are generated. Hydrogen sulphide has a powerful odour at low concentrations and is especially threatening, since at lethal concentrations this compound appears to be odourless because it inactivates human olfactory nerves. Indoor compost tunnels do not have sufficient oxygen to support human life. They are confined spaces, and testing of air for oxygen content and toxic gases, wearing of appropriate PPE, having an outside guard and proper training of involved personnel are essential.

Acid washers used for removal of ammonia from the air of compost tunnels require special care because of the large quantities of strong sulphuric or phosphoric acid that are present. Local exhaust ventilation should be provided.

Exposure to disinfectants, fungicides and pesticides can take place through the skin by exposure, through the lungs by breathing, and through the mouth by swallowing. Usually fungicides are applied by a high-volume technique such as by spray lorries, spray guns and drenching. Pesticides are applied with low-volume techniques such as misters, dynafogs, turbofogs and by fumigation. The small particles that are created remain in the air for hours. The right protective clothing and a respirator that has been certified as appropriate for the chemicals involved should be worn. Although the effects of acute poisoning are very dramatic, it should not be forgotten that the effects of chronic poisoning, although less dramatic at first glance, also always require occupational health surveillance.

Biological factors

Biological agents can cause infectious diseases as well as severe allergic reactions (Pepys 1967). No human infectious disease cases caused by the presence of human pathogens in compost have been reported. However, mushroom worker’s lung (MWL) is a severe respiratory disease that is associated with handling the compost for Agaricus (Bringhurst, Byrne and Gershon-Cohen 1959). MWL, which belongs to the group of diseases designated extrinsic allergic alveolitis (EAA), arise from exposure to spores of the thermophilic actinomycetes Excellospora flexuosa, Thermomonospora alba, T. curvata and T. fusca that have grown during the conditioning phase in compost. They can be present in high concentrations in the air during spawning of phase 2 compost (i.e., over 109 colony-forming units (CFU) per cubic metre of air) (Van den Bogart et al. 1993); for causation of EAA symptoms, 108 spores per cubic metre of air are sufficient (Rylander 1986). The symptoms of EAA and thus MWL are fever, difficult respiration, cough, malaise, increase in number of leukocytes and restrictive changes of lung function, starting only 3 to 6 hours after exposure (Sakula 1967; Stolz, Arger and Benson 1976). After a prolonged period of exposure, irreparable damage is done to the lung due to inflammation and reactive fibrosis. In one study in the Netherlands, 19 MWL patients were identified among a group of 1,122 workers (Van den Bogart 1990). Each patient demonstrated a positive response to inhalation provocation and possessed circulating antibodies against spore antigens of one or more of the actinomycetes mentioned above. No allergic reaction had been found with Agaricus spores (Stewart 1974), which may indicate low antigenicity of the mushroom itself or low exposure. MWL can easily be prevented by providing workers with powered air-purifying respirators equipped with a fine dust filter as part of their normal work gear during spawning of compost.

Some pickers have been found to suffer from damaged skin of finger tips, caused by exogenous glucanases and proteases of Agaricus. Wearing gloves during picking prevents this.

Stress

Mushroom growing has a short and complicated growing cycle. Thus managing a mushroom farm brings worries and tensions which may extend to the workforce. Stress and its management are discussed elsewhere in this Encyclopaedia.

The Oyster Mushroom

Oyster mushrooms, Pleurotus spp., can be grown on a number of different lignocellulose-containing substrates, even on cellulose itself. The substrate is wetted and usually pasteurized and conditioned. After spawning, mycelial growth takes place in trays, shelves, special containers or in plastic bags. Fructification takes place when the ambient carbon dioxide concentration is decreased by ventilation or by opening the container or bag.

Health risks

Health risks associated with the cultivation of oyster mushrooms are comparable to those linked to Agaricus as described above, with one major exception. All Pleurotus species have naked lamellae (i.e., not covered by a veil), which results in the early shedding of a large number of spores. Sonnenberg, Van Loon and Van Griensven (1996) have counted spore production in Pleurotus spp. and found up to a billion spores produced per gram of tissue per day, depending on species and developmental stage. The so-called sporeless varieties of Pleurotus ostreatus produced about 100 million spores. Many reports have described the occurrence of EAA symptoms after exposure to Pleurotus spores (Hausen, Schulz and Noster 1974; Horner et al. 1988; Olson 1987). Cox, Folgering and Van Griensven (1988) have established the causal relation between exposure to Pleurotus spores and occurrence of EAA symptoms caused by inhalation. Because of the serious nature of the disease and the high sensitivity of humans, all workers should be protected with dust respirators. Spores in the growing room should at least partially be removed before workers enter the room. This can be done by directing the circulation air over a wet filter or by setting ventilation at full power 10 minutes before workers enter the room. Weighing and packing of mushrooms can be done under a hood, and during storage the trays should be covered by foil to prevent release of spores into the working environment.

Shiitake Mushrooms

In Asia this tasty mushroom, Lentinus edodes, has been grown on wood logs in the open air for centuries. The development of a low-cost cultivation technique on artificial substrate in growing rooms rendered its culture economically feasible in the western world. The artificial substrates usually consist of a wetted mixture of hardwood sawdust, wheat straw and high-concentration protein meal, which is pasteurized or sterilized before spawning. Mycelial growth takes place in bags, or in trays or shelves, depending on the system used. Fruiting is commonly induced by temperature shock or by immersion in ice-cold water, as is done to induce production on wood logs. Due to its high acidity (low pH), the substrate is susceptible to infection by green moulds such as Penicillium spp. and Trichoderma spp. Prevention of the growth of those heavy sporulators requires either sterilization of the substrate or use of fungicides.

Health risks

The health risks associated with the cultivation of shiitake are comparable with those of Agaricus and Pleurotus. Many strains of shiitake sporulate easily, leading to concentrations of up to 40 million spores per cubic metre of air (Sastre et al. 1990).

Indoor cultivation of shiitake has regularly led to EAA symptoms in workers (Cox, Folgering and Van Griensven 1988, 1989; Nakazawa, Kanatani and Umegae 1981; Sastre et al. 1990) and inhalation of spores of shiitake is the cause of the disease (Cox, Folgering and Van Griensven 1989). Van Loon et al. (1992) have shown that in a group of 5 patients tested, all had circulating IgG-type antibodies against shiitake spore antigens. Despite the use of protective mouth masks, a group of 14 workers experienced a rise in antibody titres with increased duration of employment, indicating the need for better prevention, such as powered air-purifying respirators and appropriate engineering controls.

Acknowledgement: The view and results presented here are strongly influenced by the late Jef Van Haaren, M.D., a fine person and gifted occupational health physician, whose humane approach to the effects of human labour was best reflected in Van Haaren (1988), his chapter in my textbook that formed the basis of the present article.

AQUATIC PLANTS

Melvin L. Myers and J.W.G. Lund*

*Adapted from J.W.G. Lund’s article, “Algae”, “Encyclopaedia of Occupational Health and Safety,” 3rd edition.

Worldwide aquaculture production totalled 19.3 million tonnes in 1992, of which 5.4 million tonnes came from plants. In addition, much of the feed used on fish farms is water plants and algae, contributing to their growth as a part of aquaculture.

Water plants that are grown commercially include water spinach, watercress, water chestnuts, lotus stems and various seaweeds, which are grown as low-cost foods in Asia and Africa. Floating water plants that have commercial potential are duckweed and water hyacinth (FAO 1995).

Algae are a diverse group of organisms; if the cyanobacteria (blue-green algae) are included, they come in a range of sizes from bacteria (0.2 to 2 microns) to giant kelps (40 m). All algae are capable of photosynthesis and can liberate oxygen.

Algae are nearly all aquatic, but they may also live as a dual organism with fungi as lichens on drier rocks and on trees. Algae are found wherever there is moisture. Plant plankton consists almost exclusively of algae. Algae abound in lakes and rivers, and on the seashore. The slipperiness of stones and rocks, the slimes and discolourations of water usually are formed by aggregations of microscopic algae. They are found in hot springs, snowfields and Antarctic ice. On mountains they can form dark slippery streaks (Tintenstriche) that are dangerous to climbers.

There is no general agreement about algae classification, but they are commonly divided into 13 major groups whose members may differ markedly from one group to another in colour. The blue-green algae (Cyanophyta) are also considered by many microbiologists to be bacteria (Cyanobacteria) because they are procaryotes, which lack the membrane-bounded nuclei and other organelles of eukaryotic organisms. They are probably descendants of the earliest photosynthetic organisms, and their fossils have been found in rocks some 2 billion years old. Green algae (Chlorophyta), to which Chlorella belongs, has many of the characteristics of other green plants. Some are seaweeds, as are most of the red (Rhodophyta) and brown (Phaeophyta) algae. Chrysophyta, usually yellow or brownish in colour, include the diatoms, algae with walls made of polymerized silicon dioxide. Their fossil remains form industrially valuable deposits (Kieselguhr, diatomite, diatomaceous earth). Diatoms are the main basis of life in the oceans and contribute about 20 to 25% of the world’s plant production. Dinoflagellates (Dinophyta) are free-swimming algae especially common in the sea; some are toxic.

Uses

Water culture can vary greatly from the traditional 2-month to annual growing cycle of planting, then fertilizing and plant maintenance, followed by harvesting, processing, storage and sale. Sometimes the cycle is compressed to 1 day, such as in duckweed farming. Duckweed is the smallest flowering plant.

Some seaweeds are valuable commercially as sources of alginates, carrageenin and agar, which are used in industry and medicine (textiles, food additives, cosmetics, pharmaceuticals, emulsifiers and so on). Agar is the standard solid medium on which bacteria and other micro-organisms are cultivated. In the Far East, especially in Japan, a variety of seaweeds are used as human food. Seaweeds are good fertilizers, but their use is decreasing because of the labour costs and the availability of relatively cheap artificial fertilizers. Algae play an important part in tropical fish farms and in rice fields. The latter are commonly rich in Cyanophyta, some species of which can utilize nitrogen gas as their sole source of nitrogenous nutrient. As rice is the staple diet of the majority of the human race, the growth of algae in rice fields is under intensive study in countries such as India and Japan. Certain algae have been employed as a source of iodine and bromine.

The use of industrially cultivated microscopic algae has often been advocated for human food and has a potential for very high yields per unit area. However, the cost of dewatering has been a barrier.

Where there is a good climate and inexpensive land, algae can be used as part of the process of sewage purification and harvested as animal food. While a useful part of the living world of reservoirs, too much algae can seriously impede, or increase the cost of water supply. In swimming pools, algal poisons (algicides) can be used to control algal growth, but, apart from copper in low concentrations, such substances cannot be added to water or domestic supplies. Over-enrichment of water with nutrients, notably phosphorus, with consequent excessive growth of algae, is a major problem in some regions and has led to bans on the use of phosphorus-rich detergents. The best solution is to remove the excess phosphorus chemically in a sewage plant.

Duckweed and a water hyacinth are potential livestock feeds, compost input or fuel. Aquatic plants are also used as feed for noncarnivorous fish. Fish farms produce three primary commodities: finfish, shrimp and mollusc. Of the finfish portion, 85% are made up of noncarnivorous species, primarily the carp. Both the shrimp and mollusc depend upon algae (FAO 1995).

Hazards

Abundant growths of freshwater algae often contain potentially toxic blue-green algae. Such “water blooms” are unlikely to harm humans because the water is so unpleasant to drink that swallowing a large and hence dangerous amount of algae is unlikely. On the other hand, cattle may be killed, especially in hot, dry areas where no other source of water may be available to them. Paralytic shellfish poisoning is caused by algae (dinoflagellates) on which the shellfish feed and whose powerful toxin they concentrate in their bodies with no apparent harm to themselves. Humans, as well as marine animals, can be harmed or killed by the toxin.

Prymnesium (Chrysophyta) is very toxic to fish and flourishes in weakly or moderately saline water. It presented a major threat to fish farming in Israel until research provided a practical method of detecting the presence of the toxin before it reached lethal proportions. A colourless member of the green algae (Prototheca) infects humans and other mammals from time to time.

There have been a few reports of algae causing skin irritations. Oscillatoria nigroviridis are known to cause dermatitis. In freshwater, Anaebaena, Lyngbya majuscula and Schizothrix can cause contact dermatitis. Red algae are known to cause breathing distress. Diatoms contain silica, so they could pose a silicosis hazard as a dust. Drowning is a hazard when working in deeper water while cultivating and harvesting water plants and algae. The use of algicides also poses hazards, and precautions provided on the pesticide label should be followed.

COFFEE CULTIVATION

Jorge da Rocha Gomes and Bernardo Bedrikow

It is thought that the word coffee derives from Kaffa, a village in Ethiopia where the plant is thought to have its origin. Some, however, consider that the word stems from qahwa, meaning wine in Arabic. Coffee cultivation spread the world over, starting in Arabia (one species is called Coffea arabica, and a variety is Moka, named after an Arab village), passing through many countries, such as Ceylon, Java, India, the Philippines, Hawaii and Viet Nam, among others, some of which are important producers to this day. In America, coffee was introduced from plants previously adapted to the climate in Amsterdam and Paris, planted in Martinique, Surinam and French Guyana, from where it was brought to Brazil, the largest producing country in the world.

World production may be estimated from figure 64.36 . The 1995–96 crop generated wealth estimated at approximately US$27 million, indicating the economic significance of this product worldwide.

Figure 64.36 World coffee production for 1995 - 96

The trend towards a global economy, growing competition and the search for technologies with higher productivity also have effects upon coffee cultivation. Mechanization is being disseminated and updated. Moreover, new methods of cultivation are introduced, among them high-density cultivation, in which the distance between plants is being reduced. This modern method increases the number of coffee trees from 3,000 or 4,000 to 100,000 plants per hectare, with an increase in productivity of around 50% over the traditional method. This procedure is important for workers’ health, since lower risks are involved and less herbicide is applied, especially after the third year. On the other hand, there is an increase in the frequency of tree cutting and higher demand for control of fungus disease in the plants.

Coffee is highly sensitive to fluctuations in international commerce; many countries tend to replace coffee with other crops in which financial return is more predictable. In Brazil, for instance, coffee represented 68% of the total volume of exports in 1920; in the 1990s it is only 4%. Coffee is being replaced by soy bean, citric fruits, corn, latex and especially sugar cane.

It is extremely difficult to obtain a reliable estimate of the total labour force involved in coffee cultivation because the number of employed workers is quite variable. During harvest, a large number of seasonal workers are hired, to be dismissed soon after the crop is over. Moreover, in small properties, very often workers are not legally registered, and therefore are not shown in official reports. In Brazil in 1993, for a production of 28.5 million coffee bags, the number of workers was estimated at 1.1 million in direct and 4 to 5 million in indirect jobs. If the same parameters are applied to world production for the same year, coffee workers around the world could be estimated at approximately 3.6 million.

It is equally difficult to know the average figure of workers per rural property. In general, small or medium-sized properties are predominant. The sex and age distribution of the working population is equally unknown, even though female population among workers is increasing and children are known to be employed in coffee plantations. Figures for unionized workers vary according to the labour policies in each country, but they are known to be generally scarce.

Operations

Coffee cultivation and treatment involve the following steps: tree abatement; soil preparation; planting (small plants are usually grown in nurseries in the same or in external properties); treatment (soil correction, fertilizing, pest control and terrain cleaning manually or with herbicides); fruit picking (ripe fruit is usually red and therefore called a berry—see figure 64.37) ; sieving to get rid of impurities; transportation; washing to remove pulp and membranes; sun drying, revolving grains with a rake, or mechanical drying through hot air blasting; hand separation of grains; storing in silos; and bagging.

Figure 64.37 High-density coffee cultivation showing berries

Estado de Sao Paulo

Potential Risks

Risk factors that may affect workers’ health in coffee cultivation are the same as for agricultural workers in general.

From tree abatement and terrain preparation to the final storage of coffee bags, each step may involve several risk factors for workers’ health and safety. Injury risks are present mainly in mechanized processes, tree abatement, terrain preparation, mechanical picking, transportation of coffee and workers as well, fruit treatment (including the risk of boiler explosion) and use of hand tools (very often improvised or without maintenance).

Potential risks of occupational diseases due to physical conditions are related to heat exposure in drying operations, solar radiation, machine noise, ergonomic problems from hand tools, vibration from machinery and tractors, and cold and humidity from outdoor exposure.

The main chemical agents present as potential risks for workers’ health are pesticides and herbicides. Those most often used are gliphosate as an herbicide, copper salts as fungicides and organophosphorus compounds for other pests commonly found on coffee trees. The number of pesticide applications varies according to tree age, soil composition, climatic conditions, vegetation species or variety, cultivation system (e.g., high or low density) and other factors. Spraying is usually done individually with backpack equipment, or from tractors. Large amounts are usually required, and it is said that “without spraying no crop is available”.

Chemical fertilizers may also present a health risk. Often used are compounds derived from boron, zinc, nitrogen, sodium, potassium, calcium, magnesium and sulphur. The release of particles from fertilizer handling should be kept under control.

Biological agents may represent important risks for workers’ health. They may include, for instance, bites or stings from snakes, spiders, bees, mosquitoes and acarids, some of them important as disease vectors. In certain areas, endemic diseases may be serious risks for coffee workers.

Ergonomic, psychosocial and organizational factors are discussed below.

Health Effects

Examples of injuries related to work are cuts from hand tools, sprains and fractures from machines and injuries from tractors. Fatal injuries, even if unusual, have occurred as a result of overturning of tractors or inadequate vehicles used in transportation of workers. When artificial drying is employed, heat sources may cause burns and explosions.

Occupational diseases may result from exposure to solar ultraviolet radiation; cutaneous conditions may range from a simple erythema to skin cancer. Hearing loss among machine operators, pulmonary allergic conditions, poisoning from herbicides and pesticides, callosities, lung diseases, bone and circulatory conditions due to vibration, and muscular and skeletal trouble due to poor ergonomic positions or excessive weight (one coffee bag can weigh 60 kg) are other occupational conditions that may occur among coffee cultivation workers. Although primarily a problem among workers processing coffee beans, green bean handlers have complained of respiratory and eye problems. Coffee bean dust has been associated with occupational dust diseases.

Tropical diseases such as malaria, yellow fever, filariasis, trypanossomiasis, leishmaniasis and onchocercosis are prevalent in certain cultivating areas. Tetanus is still prevalent in many rural areas.

More complex health problems related to psychosocial and organizational factors may also affect coffee workers. Since large numbers of workers are required during harvest, and very few during the rest of the year, seasonal contracts are usually practised, often resulting in difficult health problems.

In many cases, workers leave their families and remain during the harvest season in precarious lodgings under inadequate sanitary conditions. If the planting area is close to town, the farmer will contract only one man in the family. However, to increase the profit, the worker himself may bring his whole family to help, including women and children. In some areas, the number of children at work is so high that schools will be closed during the whole harvest season.

In this type of seasonal activity, workers will turn from one type of cultivation to another, according to each harvest period. Since men leave their families, women are called “widows with living husbands”. Very often, a man will raise another family, away from his original town.

Proper compliance with labour legislation and social security is usually restricted to large plantations, and labour inspection in rural areas is generally ineffective. Health care is usually very limited. Duration of work is extended to many hours daily; weekends and normal vacations are seldom respected.

These psychosocial and organizational factors result in marked deterioration in workers’ health, manifested through early ageing, low life expectancy, increase in prevalence and longer duration of diseases, malnutrition (eating the food taken to the field in cans without heating it has led to workers being given a nickname—boias frias in Portuguese), anaemia and hypovitaminoses leading to loss of disposition to work, mental trouble and other manifestations.

Prevention

Preventive measures concerning coffee are the same that apply to rural work in general. Collective protection includes machine guarding, care in application of pesticides and herbicides, mechanizing operations that require undue effort and energy consumption, and adequate transportation of workers. In high-density plantations, regular cutting will not allow the trees to grow, which will eliminate the use of dangerous and uncomfortable ladders for hand picking. When drying requires the use of boilers, careful periodic preventive maintenance is of utmost importance. Biological pest control and proper selection of species resistant to plagues are important preventive measures concerning pesticides, avoiding workers’ disease and environmental protection as well.

Implementation of the use of recommended PPE is difficult because such equipment is usually not adapted to climatic conditions or to the biotype of workers. Moreover, there is usually no educational orientation to facilitate the use, and the selection of equipment is not always correct. Equipment in general use is restricted to boots, hats and clothing to protect from the weather, even though hand, lung, eye and ear protection may be required.

Prevention to control psychosocial and organizational factors may bring up many difficulties. Workers’ awareness should be raised through educational activities, especially in unions and other workers’ organizations, increasing perceptions about workers’ rights to better living and working conditions; moreover, employers should develop their perceptions concerning their social responsibilities towards the labour force. The State should exercise an effective and constant orientation and enforcement wherever legal action is required. Some countries have developed rules and regulations specifically applicable to rural workers. In Brazil, for example, Rural Regulatory Standards establish general directives concerning safety in rural activities, the organization of occupational health services and safety committees in plantations, use of personal protective equipment and handling of chemicals (pesticides, fertilizers and soil-correcting products).

Health control through occupational medicine should cover the evaluation of health effects due to exposure to pesticides, ultraviolet radiation, excessive noise and many other hazards. It may, in many circumstances, be more necessary to control worm diseases, anaemia, hypertension, behavioural problems, eye defects and similar problems, due to their high prevalence in rural areas. Health education should be stressed, as well as tetanus immunization, including for pregnant workers to prevent neonatal tetanus. In some regions, immunization against yellow fever is necessary. Chemoprophylaxis is recommended in areas where malaria is endemic, together with the use of repellents and a preventive orientation against mosquitoes, until sanitation is adequate to control or suppress vectors of the aetiological agent. Serum against snake poison should be available.

Acknowledgement: The authors are obliged to the cooperation received from Professor Nelson Batista Martin, from the Institute of Rural Economy, State Secretary of Agriculture, Sao Paulo; Andre Nasser and Ricardo Luiz Zucas, from the Brazilian Rural Society; and Monica Levy Costa, from the School Health Center, School of Public Health, Sao Paulo University.

TEA CULTIVATION

L.V.R. Fernando*

*Adapted from 3rd edition, “Encyclopaedia of Occupational Health and Safety”.

Tea (Camellia sinensis) was originally cultivated in China, and most of the world’s tea still comes from Asia, with lesser quantities from Africa and South America. Ceylon and India are now the largest producers, but sizeable quantities also come from China, Japan, the former USSR, Indonesia and Pakistan. The Islamic Republic of Iran, Turkey, Viet Nam and Malaysia are small-scale growers. Since the Second World War, the area under tea cultivation in Africa has been expanding rapidly, particularly in Kenya, Mozambique, Congo, Malawi, Uganda and the United Republic of Tanzania. Mauritius, Rwanda, Cameroon, Zambia and Zimbabwe also have small acreages. The main South American producers are Argentina, Brazil and Peru.

Plantations

Tea is most efficiently and economically produced in large plantations, although it is also grown as a smallholder crop. In Southeast Asia, the tea plantation is a self-contained unit, providing accommodation and all facilities for its workers and their families, each unit forming a virtually closed community. Women form a large proportion of the workers in India and Ceylon, but the pattern is somewhat different in Africa, where mainly male migrant and seasonal labour is employed and families do not have to be housed. See also the article “Plantations” in this chapter.

Cultivation

Land is cleared and prepared for new planting, or areas of old, poor-quality tea are uprooted and replanted with high-yielding vegetatively propagated cuttings. New fields take a couple of years to come into full bearing. Regular programmes of manuring, weeding and pesticide application are carried on throughout the year.

The plucking of the young tea leaves—the famous “two leaves and a bud”—takes place the year round in most of Southeast Asia, but is restricted in areas with a marked cold season (see figure 64.38). After a cycle of plucking which lasts about 3 to 4 years, bushes are pruned back fairly drastically and the area weeded. Hand weeding is now widely giving way to the use of chemical herbicides. The plucked tea is collected in baskets carried on the backs of the pluckers and taken down to centrally located weighing sheds, and from these to the factories for processing. In some countries, notably Japan and the former USSR, mechanical plucking has been carried out with some success, but this requires a reasonably flat terrain and bushes grown in set rows.

Figure 64.38 Tea pluckers at work on a plantation in Uganda

Hazards and Their Prevention

Falls and injuries caused by agricultural implements of the cutting and digging type are the most common types of accidents. This is not unexpected, considering the steep slopes on which tea is generally grown and the type of work involved in the processes of clearing, uprooting and pruning. Apart from exposure to natural hazards like lightning, workers are liable to be bitten by snakes or stung by hornets, spiders, wasps or bees, although highly venomous snakes are seldom found at the high altitudes at which the best tea grows. An allergic condition caused by contact with a certain species of caterpillar has been recorded in Assam, India.

The exposure of workers to ever-increasing quantities of highly toxic pesticides requires careful control. Substitution with less-toxic pesticides and attention to personal hygiene are necessary measures here. Mechanization has been fairly slow, but an increasing number of tractors, powered vehicles and implements are coming into use, with a concomitant increase in accidents from these causes (see figure 64.39). Well-designed tractors with safety cabs, operated by trained, competent drivers will eliminate many accidents.

Figure 64.39 Mechanical harvesting on a tea plantation near the Black Sea

In Asia, where the non-working population resident on the tea estates is almost as great as the workforce itself, the total number of accidents in the home is equal to that of accidents in the field.

Housing is generally substandard. The most common diseases are those of the respiratory system, closely followed by enteric diseases, anaemia and substandard nutrition. The former are mainly the outcome of working and living conditions at high altitudes and exposure to low temperatures and inclement weather. The intestinal diseases are due to poor sanitation and low standards of hygiene among the labour force. These are mainly preventable conditions, which underlines the need for better sanitary facilities and improved health education. Anaemia, particularly among working mothers of child-bearing age, is all too common; it is partly the result of ankylostomiasis, but is due mainly to protein-deficient diets. However, the principal causes of lost work time are generally from the more minor ailments and not serious diseases. Medical supervision of both housing and working conditions is an essential preventive measure, and official inspection, either at local or national level, is also necessary to ensure that proper health facilities are maintained.

HOPS

Thomas Karsky and William B. Symons

Hops are used in brewing and are commonly grown in the Pacific Northwest of the United States, Europe (especially Germany and the United Kingdom), Australia and New Zealand.

Hops grow from rhizome cuttings of female hop plants. Hop vines grow up to 4.5 to 7.5 m or more during the growing season. These vines are trained to climb up heavy trellis wire or heavy cords. Hops are traditionally spaced 2 m apart in each direction with two cords per plant going to the overhead trellis wire at about 45° angles. Trellises are about 5.5 m high and are made from 10 × 10 cm pressure-treated timbers or poles sunk 0.6 to 1 m into the ground.

Manual labour is used to train the vines after the vines reach about a third of a metre in length; additionally, the lowest metre is pruned to allow air circulation to reduce disease development.

Hops vines are harvested in the fall. In the United Kingdom, some hops are grown in trellises 3 m high and harvested with an over-the-row mechanical harvester. In the United States, hop combines are available to harvest 5.5-m-high trellises. The areas that the harvesters (field strippers) are unable to get are harvested by hand with a machete. Newly harvested hops are then kiln dried from 80% moisture to about 10%. Hops are cooled, then baled and taken to cold storage for end use.

Safety Concerns

Workers need to wear long sleeves and gloves when working near the vines, because hooked hairs of the plant may cause a rash on the skin. Some individuals become more sensitized to the vines than others.

A majority of the injuries involve strains and sprains due to lifting materials such as irrigation pipes and bales, and over-reaching when working on trellises. Workers should be trained in lifting or mechanical aids should be used.

Workers need to wear chaps at the knee and below to protect the leg from cuts while cutting the vines by hand. Eye protection is a must while working with the vines.

Many injuries occur while workers tie twine to the wire trellis wire. Most work is performed while standing on high trailers or platforms on tractors. Accidents have been reduced by providing safety belts or guard rails to prevent falls, and by wearing eye protection. Because there is much movement with the hands, carpal tunnel syndrome may be a problem.

Since hops are often treated with fungicides during the season, proper posting of re-entry intervals is needed.

Worker’s compensation claims in Washington State (US) tend to indicate that injury incidence ranges between 30 and 40 injuries per 100 person years worked. Growers through their association have safety committees that actively work to lower injury rates. Injury rates in Washington are similar to those found in the tree fruit industry and dairy. Highest injury incidence tends to occur in August and September.

The industry has unique practices in the production of the product, where much of the machinery and equipment is locally manufactured. By the vigilance of the safety committees to provide adequate machine guarding, they are able to reduce “caught in” type injuries within the harvesting and processing operations. Training should focus on proper use of knives, PPE and prevention of falls from vehicles and other machines.

HEALTH PROBLEMS AND DISEASE PATTERNS IN AGRICULTURE

Melvin L. Myers

At the end of the twentieth century, less than 5% of the workforce in industrialized nations is employed in agriculture, while nearly 50% of the worldwide workforce is engaged in agriculture (Sullivan et al. 1992). The work varies from highly mechanized to the manually arduous. Some agribusiness has been historically international, such as plantation farming and the growing of export crops. Today, agribusiness is international and is organized around commodities such as sugar, wheat and beef. Agriculture covers many settings: family farms, including subsistence agriculture; large corporate farms and plantations; urban farms, including specialty enterprises and subsistence agriculture; and migrant and seasonal work. Crops vary from widely used staples, such as wheat and rice, to specialty crops such as coffee, fruits and seaweed. Moreover, the young and the old engage in agricultural work to a greater extent than any other industry. This article addresses health problems and disease patterns among agricultural workers except for livestock rearing, which is covered in another chapter.

Overview

The image of agricultural work is that of a healthy pursuit, far from congested and polluted cities, that provides an opportunity for plenty of fresh air and exercise. In some ways, this is true. US farmers, for example, have a lower mortality rate for ischemic heart disease and cancer as compared with other occupations.

However, agricultural work is associated with a variety of health problems. Agricultural workers are at a high risk for particular cancers, respiratory diseases and injuries (Sullivan et al. 1992). Because of the remote location of much of this work, emergency health services are lacking, and agromedicine has been viewed as a vocation without high social status (see article “Agromedicine” and table 64.12). The work environment involves exposure to the physical hazards of weather, terrain, fires and machinery; toxicological hazards of pesticides, fertilizers and fuels; and health insults of dust. As shown in table 64.13, table 64.14, table 64.15, table 64.16, table 64.17, table 64.18 and table 64.19, agriculture is associated with a variety of health hazards. In these tables and the corresponding descriptions that follow, six categories of hazards are summarized: (1) respiratory, (2) dermatological, (3) toxic and neoplastic, (4) injury, (5) mechanical and thermal stress and (6) behavioural hazards. Each table also provides a summary of interventions to prevent or control the hazard.

Table 64.12 Comparison of two types of agromedicine programmes

Parameter

Model A

Model B

Site (campus)

Medical

Medical and agricultural

Support

Federal, foundation

State, foundation

Research

Primary (basic)

Secondary (applied)

Patient education

Yes

Yes

Producer/worker education

Yes

Yes

Health provider education

Yes

Yes

Extension education

Elective

Yes

Cross-discipline education

Elective

Yes

Statewide community outreach

Intermittent

Ongoing (40 hours/wk)

Constituency:sustainability

Academic peers

National peers

International peers

Growers, consumers,  health professionals,  rural physicians

Prestige (academic)

Yes

Little

Growth (capital, grants)

Yes

Little

Administration

Single

Dual (partners)

Primary focus

Research, publication, policy recommendations

Education, public service, client-based research

Table 64.13 Respiratory hazards

Exposures

Health effects

Cereal grain pollen, livestock dander, fungal antigens in grain dust and on crops, dust mites, organophosphorus insecticides

Asthma and rhinitis: Immunoglobin E-mediated asthma

Organic dusts

Nonimmunologic asthma (grain dust asthma)

Specific plant parts, endotoxins, mycotoxins

Mucous membrane inflammation

Insecticides, arsenic, irritant dust, ammonia, fumes, grain dust (wheat, barley)

Bronchospasm, acute and chronic bronchitis

Fungal spores or thermophilic actinomycetes released from mouldy grain or hay, antigens of less than 5mm in diameter

Hypersensitivity pneumonitis

Thermophilic actinomycetes: mouldy sugar cane

Bagassosis

Mushroom spores (during clean-out of beds)

Mushroom worker’s lung

Mouldy hay, compost

Farmer’s lung

Fungi: mouldy maple bark

Maple bark stripper’s disease

Anthropoids: infested wheat

Wheat weevil disease

Plant debris, starch granules, moulds, endotoxins, mycotoxins, spores, fungi, gram-negative bacteria, enzymes, allergens, insect parts, soil particles, chemical residues

Organic dust toxic syndrome

Dust from stored grain

Grain fever

Mouldy silage on top of silage in silo

Silo unloader’s syndrome

Decomposition gases: ammonia, hydrogen sulphide, carbon monoxide, methane, phosgene, chlorine, sulphur dioxide, ozone, paraquat (herbicide), anhydrous ammonia (fertilizer), oxides of nitrogen

Acute pulmonary responses

Nitrogen dioxide from fermenting silage

Silo filler’s disease

Welding fumes

Metal fume fever

Oxygen deficiency in confined spaces

Asphyxiation

Soil dust of arid regions

Valley fever (coccidiomycosis)

Mycobacterium tuberculosis

Tuberculosis (migrant workers)

Interventions: ventilation, dust suppression or containment, respirators, mould prevention,  smoking cessation.

Sources: Merchant et al. 1986; Meridian Research, Inc. 1994; Sullivan et al. 1992;  Zejda, McDuffie et al. 1994.

Table 64.14 Dermatological hazards

Exposures

Health effects

Ammonia and dry fertilizers, vegetable crops, bulb plants, fumigants, oat and barley dust, several pesticides, soaps, petroleum products, solvents, hypochlorite, phenolic compounds, amniotic fluid, animal feeds, furazolidone, hydroquinone, halquinol

Irritant contact dermatitis

Mites

Grain itch

Sensitizing plants (poison ivy or oak), certain pesticides (dithiocarbamates, pyrethrins, thioates, thiurams, parathion, and malathion)

Allergic contact dermatitis

Handling tulips and tulip bulbs

Tulip finger

Creosote, plants containing furocoumarins

Photo-contact dermatitis

Sunlight, ultraviolet radiation

Sun-induced dermatitis, melanoma, lip cancer

Moist and hot environments

Heat-induced dermatitis

Wet tobacco leaf contact

Nicotine poisoning (green tobacco sickness)

Fire, electricity, acid or caustic chemicals, dry (hygroscopic) fertilizer, friction, liquified anhydrous ammonia

Burns

Bites and stings from wasps, chiggers, bees, grain mites, hornets, fire ants, spiders, scorpions, centipedes, other arthropods, snakes

Arthropod-induced dermatitis, envenomation, Lyme disease, malaria

Punctures and thorn pricks

Tetanus

Interventions: Integrated pest management, protective clothing, good sanitation, vaccination,  insect control, barrier creams.

Sources: Estlander, Kanerva and Piirilä 1996; Meridian Research, Inc. 1994; Raffle et al. 1994;  Sullivan et al. 1992.

Table 64.15 Toxic and neoplastic hazards

Exposures

Possible health effects

Solvents, benzene, fumes, fumigants, insecticides (e.g., organophosphates, carbamates, organochlorines), herbicides (e.g., phenoxy-aliphatic acids, bipyridyls, triazines, arsenicals, acentanilides, dinitro-toluidine), fungicides (e.g., thiocarbamates, dicarboximides)

Acute intoxication, Parkinson’s disease, peripheral neuritis, Alzheimer’s disease, acute and chronic encephalopathy, non-Hodgkin lymphoma, Hodgkin’s lymphoma, multiple myeloma, soft-tissue sarcoma, leukaemias, cancers of the brain, prostrate, stomach, pancreas and testicle, glioma

Solar radiation

Skin cancer

Dibromochloropropane (DBCP), ethylene dibromide

Sterility (male)

Interventions: integrated pest management, respiratory and dermal protection,  good pesticide application practices, safe re-entry time into fields after pesticide application,  container labelling with safety procedures, carcinogen identification and elimination.

Sources: Connally et al. 1996; Hanrahan et al. 1996; Meridian Research, Inc. 1994;  Pearce and Reif 1990; Popendorf and Donham 1991; Sullivan et al. 1992; Zejda,  McDuffie and Dosman 1993.

Table 64.16 Injury hazards

Exposures

Health effects

Road vehicle crashes, machinery and vehicles, struck by objects, falls, oxygen depletion, fires

Fatalities

Tractors

Crushing of the chest, extravasation (escape of fluids—e.g., blood—and surrounding tissue), strangulation/asphyxia, drowning

Augers

Hypovolemia (loss of blood), sepsis and asphyxia

Electricity

Electrocutions

Machinery and vehicles, draught animal kicks and assaults, falls

Nonfatal injuries: injury infection (e.g., tetanus)

Hay balers

Friction burns, crushing, neurovascular disruption, avulsion, fractures, amputation

Power take-offs

Skin or scalp avulsion or degloving, amputation, multiple blunt injury

Corn pickers

Hand injuries (friction burns, crushing, avulsion or degloving, finger amputation)

Fires and explosions

Serious or fatal burns, smoke inhalation,

Interventions: rollover protective structures, guards, good practices, safe electrical wiring,  fire prevention, protective equipment, good housekeeping practices.

Sources: Deere & Co. 1994; Meridian Research, Inc. 1994; Meyers and Hard 1995.

Table 64.17 Percentages of lost time injuries by source of injury, nature of injury,  and activity for four types of agricultural operations, United States, 1993.

 

Cash grain

Field crops

Vegetables, fruits, nuts

Nursery crops

Source of Injury

       

Tractors

11.0

9.7

-

1.0

Machinery

18.2

18.6

25.1

12.5

Livestock

11.0

12.1

1.7

-

Hand tools

13.4

13.0

19.3

3.8

Power tools

4.3

4.6

0.4

17.9

Pesticides/chemicals

1.3

2.8

0.4

0.5

Plants or trees

2.2

3.1

7.4

4.6

Working surfaces

11.5

11.6

6.8

5.1

Trucks or automobiles

4.7

1.4

1.5

-

Other vehicles

3.6

-

3.5

-

Liquids

3.1

1.0

-

-

Other

15.6

22.2

34.0

54.5

Nature of Injury

       

Sprain/strain

20.5

23.5

39.3

38.0

Cut

16.4

32.3

18.9

21.7

Fracture

20.3

6.5

4.3

5.6

Bruise

9.3

9.5

12.6

14.8

Crush

10.4

2.6

2.4

1.0

Other

23.1

25.6

22.5

18.9

Activity

       

Farm maintenance

23.8

19.1

10.8

33.3

Field work

17.2

34.6

34.0

38.2

Crop handling

14.1

13.8

9.4

7.7

Livestock handling

17.1

14.7

5.5

3.2

Machine maintenance

22.6

10.1

18.0

-

Other

5.1

7.5

22.3

17.6

Source: Meyers 1997.

Table 64.18 Mechanical and thermal stress hazards

Exposures

Health effects

Interventions

Tendon overuse, stretching; excessive force

Tendon-related disorders (tendinitis, tenosynovitis)

Ergonomic design, vibration dampening, warm clothing, rest periods

Repetitive motion, awkward wrist posture

Carpal tunnel syndrome

 

Vibration of the hands

Raynaud’s syndrome

 

Repetition, high force, poor posture, whole-body vibration

Degenerative changes, low-back pain, intervertebral disk herniation; peripheral nerve and vascular,  gastrointestinal and vestibular system injuries

 

Motor and machinery noise

Hearing loss

Noise control, hearing protection

Increased metabolism, high temperatures and humidity, limited water and electrolytes

Heat cramps, heat exhaustion, heat stroke

Drinking water, rest breaks, protection from the sunshine

Low temperatures, lack of dry clothing

Frost nip, chilblains, frostbite, systemic hypothermia

Dry, warm clothing, heat generation from activity

Source: Meridian Research, Inc. 1994.

Table 64.19 Behavioural hazards

Exposures

Health effects

Interventions

Isolation, economic threats, intergenerational problems, violence, substance abuse, incest, pesticides, risk taking, patriarchal attitudes, unstable weather, immobility

Depression, anxiety, suicide, poor coping

Early diagnosis, counselling, empowerment, pesticide control, community support

Tuberculosis, sexually transmitted diseases (migrant workers)

Interpersonal illness

Early diagnosis, vaccination, condom use

Sources: Boxer, Burnett and Swanson 1995; Davies 1995; Meridian Research, Inc. 1994;  Parrón, Hernández and Villanueva 1996.

Respiratory Hazards

Agricultural workers are subject to several pulmonary diseases related to exposures at work as shown in table 64.13 . An excess of these diseases has been found in several countries.

Exacerbation of asthma by specific allergens and nonspecific causes has been associated with airborne dust. Several farm antigen exposures can trigger asthma, and they include pollen, storage mites and grain dust. Mucous membrane inflammation is a common reaction to airborne dust in individuals with allergic rhinitis or a history of atopy. Plant parts in grain dust appear to cause mechanical irritation to the eyes, but endotoxin and mycotoxin exposure may also be associated with the inflammation of the eyes, nasal passages and throat.

Chronic bronchitis is more common among farmers than among the general population. The majority of farmers with this illness have a history of exposure to grain dust or work in swine confinement buildings. It is believed that cigarette smoking is additive and a cause of this illness. In addition, acute bronchitis has been described in grain farmers, especially during grain harvest.

Hypersensitivity pneumonitis is caused by repeated antigen exposures from a variety of substances. Antigens include micro-organisms found in spoiled hay, grain and silage. This problem has also been seen among workers who clean out mushroom bed houses.

Organic dust toxic syndrome was originally associated with exposure to mouldy silage and was, thus, called silage unloader’s syndrome. A similar illness, called grain fever, is associated with exposure to stored grain dust. This syndrome occurs without prior sensitization, as is the case with hypersensitivity pneumonitis. The epidemiology of the syndrome is not well defined.

Farmers may be exposed to several different substances that can cause acute pulmonary responses. Nitrogen dioxide generated in silos can cause death among silo workers. Carbon monoxide generated by combustion sources, including space heaters and internal combustion engines, can cause death of agricultural workers exposed to high concentrations inside of buildings. In addition to toxic exposures, oxygen deficiency in confined spaces on farms is a continuing problem.

Many agricultural crops are causative agents for pulmonary diseases when they are processed. These include hypersensitivity pneumonitis caused by mouldy malt (from barley), paprika dust and coffee dust. Byssinosis is caused by cotton, flax and hemp dusts. Several natural products are also associated with occupational asthma when processed: vegetable gums, flax seed, castor bean, soybean, coffee bean, grain products, flour, orris root, papain and tobacco dust (Merchant et al. 1986; Meridian Research, Inc. 1994; Sullivan et al. 1992).

Dermatological Hazards

Farmers are exposed to several skin hazards, as shown table 64.14 . The most common type of agriculture-related skin disease is irritant contact dermatitis. In addition, allergic contact dermatosis is a reaction to exposures to sensitizers including certain plants and pesticides. Other skin diseases include photo-contact, sun-induced, heat-induced, and arthropod-induced dermatoses.

The skin can be burned in several ways. Burns can result from dry fertilizer, which is hygroscopic and attracts moisture (Deere & Co. 1994). When on the skin, it can draw out moisture and cause skin burns. Liquid anhydrous ammonia is used for injecting nitrogen into the soil, where it expands into a gas and readily combines with moisture. If the liquid or gas contacts the body—especially the eyes, skin and respiratory tract—cell destruction and burns can occur, and permanent injury can result without immediate treatment.

Tobacco croppers and harvesters can experience green tobacco sickness when working with damp tobacco. Water from rain or dew on the tobacco leaves probably dissolves nicotine to facilitate its absorption through the skin. Green tobacco sickness is manifested with complaints of headache, pallor, nausea, vomiting and prostration following the worker’s contact with wet tobacco leaves. Other insults to the skin include arthropod and reptile stings and bites, and thorn punctures, which can carry diseases.

Toxic and Neoplastic Hazards

The potential for toxic substances exposure in agriculture is great, as can be seen table 64.15. Chemicals used in agriculture include fertilizers, pesticides (insecticides, fumigants and herbicides) and fuels. Human exposures to pesticides are widespread in developing countries as well as in the developed countries. The United States has registered more than 900 different pesticides with more than 25,000 brand names. About 65% of the registered uses of pesticides are for agriculture. They are primarily used to control insects and to reduce crop loss. Two-thirds (by weight) of the pesticides are herbicides. Pesticides may be applied to seed, soil, crops or the harvest, and they may be applied with spray equipment or crop dusters. After application, pesticide exposures can result from off-gassing, dispersion by the wind, or contact with the plants through skin or clothing. Dermal contact is the most common type of occupational exposure. A number of health effects have been associated with pesticide exposure. These include acute, chronic, carcinogenic, immunologic, neurotoxic and reproductive effects.

Farmers experience a higher risk for some site-specific cancers. These include brain, stomach, lymphatic and haematopoietic, lip, prostrate and skin cancer. Solar and pesticide (especially herbicide) exposure have been related to higher cancer risks for farm populations (Meridian Research, Inc. 1994; Popendorf and Donham 1991; Sullivan et al. 1992).

Injury Hazards

Studies have consistently shown that agricultural workers are at increased risk of death due to injury. In the United States, a study of work-related fatalities for 1980 to 1989 reported rates in agricultural production of 22.9 deaths per 100,000 workers, as compared to 7.0 deaths per 100,000 for all workers. The average fatality rate for males and females, respectively, was 25.5 and 1.5 deaths per 100,000 workers. The leading causes of death in agricultural production were machinery and motor vehicles. Many studies report the tractor as the leading machine involved in fatalities, frequently from tractor rollovers. Other leading causes of death include electrocutions, caught in, flying objects, environmental causes and drowning. Age is an important risk factor related to agricultural fatalities for males. For example, the fatality rate for agricultural workers in the US over the age of 65 was over 50 per 100,000 workers, more than double the overall average (Meyers and Hard 1995) (see figure 64.40). Table 64.16  shows several injury hazard exposures, their consequences and recognized interventions.

Figure 64.40 Agricultural workers fatality rates, US, 1980-89

A 1993 survey of farm injuries in the United States found the major injury sources to be livestock (18%), machinery (17%) and hand tools (11%). The most frequent injuries reported in this study were sprain and strain (26%), cut (18%) and fracture (15%). Males represented 95% of the injuries, while the highest concentration of injuries occurred among workers 30 to 39 years of age. Table 64.17 shows the source and nature of injury and the activity during injury for four major crop production categories. The National Safety Council estimated a US rate of 13.2 occupational injuries and illnesses per 100 crop production workers in 1992. More than half of these injuries and illnesses reulted in an average of 39 days away from work. In contrast, the manufacturing and construction sectors had an injury and illness incidence rate of, respectively, 10.8 and 5.4 per 100 workers. In another study in the United States, investigators determined that 65% of all farm injuries required medical attention and that machinery other than tractors caused nearly half of the injuries that resulted in permanent disability (Meridian Research, Inc. 1994; Boxer, Burnett and Swanson 1995).

Mechanical and Thermal Stress Hazards

As discussed above, sprains and strains are a significant problem among agricultural workers, and as shown in table 64.18 , agricultural workers are exposed to several mechanical and thermal stresses that result in injury. Many of these problems result from handling heavy loads, repetitive motion, poor posture and dynamic motion. In addition, agricultural vehicle operators are exposed to whole-body vibration. One study reported the prevalence of low-back pain to be 10% greater among tractor drivers.

Noise-induced hearing loss is common among agricultural workers. One study reported that farmers more than 50 years of age have as much as 55% hearing loss. A study of rural students found that they have two times greater hearing loss than urban students.

Agricultural workers are exposed to temperature extremes. They may be exposed to hot, humid environments in work in the tropical and subtropical zones, and during the summer in the temperate zones. Heat stress and stroke are hazards under these conditions. Conversely, they may be exposed to extreme cold in the temperate zones in the winters and possible frostbite or death from hypothermia (Meridian Research, Inc. 1994).

Behavioural Hazards

Some aspects of farming can cause stress among farmers. As shown in table 64.19 , these include isolation, risk taking, patriarchal attitudes, pesticide exposures, unstable economies and weather, and immobility. Problems associated with these circumstances include dysfunctional relationships, conflicts, substance abuse, home violence and suicide. Most suicides associated with depression on farms in North America involve victims who are married and are full-time farmers, and most use firearms to commit suicide. The suicides tend to happen during peak farming periods (Boxer, Burnett and Swanson 1995).

Migrant farm labourers are at high risk of tuberculosis, and where male workers predominate, sexually transmitted diseases are a problem. Female migrant workers experience problems of appropriate perinatal outcome, high infant mortality rates, and low occupational risk perceptions. A broad range of behavioural issues is currently being investigated among migrant workers, including child abuse and neglect, domestic violence, substance abuse, mental disorders and stress-related conditions (ILO 1994).

AGROMEDICINE

Stanley H. Schuman and Jere A. Brittain

Since animal husbandry and crop production began, agriculture and medicine have been interrelated. A healthy farm or livestock operation requires healthy workers. Famine, drought, or pestilence can overwhelm the well-being of all of the interrelated species on the farm; especially in developing countries that depend on agriculture for survival. In colonial times plantation-owners had to be aware of hygienic measures to protect their plants, animals and human workers. At present, examples of agromedical teamwork include: integrated pest management (an ecological approach to pests); tuberculosis (TB) prevention and control (livestock, dairy products and workers); and agricultural engineering (to reduce trauma and farmer’s lung). Agriculture and medicine succeed when they work together as one.

Definitions

The following terms are used interchangeably, but there are noteworthy connotations:

·     Agricultural medicine refers to the subdivision of public health and/or occupational medicine included in the training and practice of health professionals.

·     Agromedicine is a term coined in the 1950s to emphasize interdisciplinary, programmatic approaches which give a greater role for the agricultural professional based upon the equal partnership of the two disciplines (medicine and agriculture).

In recent years, the definition of agricultural medicine as a subspeciality of occupational/environmental medicine located on the health sciences campus has been challenged to develop a broader definition of agromedicine as a process of linking agricultural and health resources of a state or a region in a partnership dedicated to public service, along the lines of the original land-grant university model.

The essential unity of biological science is well known to plant chemists (nutrition), animal chemists (nutrition) and human chemists (nutrition); the areas of overlap and integration go beyond the boundaries of narrowly defined specialization.

Content areas

Agromedicine has focused on three core areas:

1.     traumatic injury

2.     pulmonary exposures

3.     agrichemical injury.

Other content areas, including zoonoses, rural health services and other community services, food safety (e.g., the relationship between nutrition and cancer), health education and environmental protection, have received secondary emphasis. Other initiatives relate to biotechnology, the challenge of population growth and sustainable agriculture.

Each core area is emphasized in university training and research programmes depending on faculty expertise, grants and funding initiatives, extension needs, commodity producers’ or corporate requests for consultation and networks of inter-university cooperation. For example, traumatic injury skills may be supported by a faculty in agricultural engineering leading to a degree in that branch of agricultural science; farmer’s lung will be covered in a pulmonary medicine rotation in a residency in occupational medicine (post-graduate specialization residency) or in preventive medicine (leading to a master’s or doctorate in public health); an inter-university food safety programme may link the veterinary discipline, the food science discipline and the infectious disease medical speciality. Table 64.12  compares two types of programmes.

In the United States, a number of states have established agromedicine programmes. Alabama, California, Colorado, Georgia, Iowa, Kansas, Kentucky, Minnesota, Mississippi, Nebraska, New York, Oregon, Pennsylvania, South Carolina, Virginia and Wisconsin have active programmes. Other states have programmes which do not use the terms agromedicine or agricultural medicine or which are at early stages of development. These include Michigan, Florida and Texas. Saskatchewan, Canada, also has an active agromedicine programme.

Conclusion

In addition to collaboration across disciplines in so-called basic science, communities need greater coordination of agricultural expertise and medical expertise. Dedicated localized teamwork is required to implement a preventive, educational approach that delivers the best science and the best outreach that a state-funded university system can provide to its citizens.

ENVIRONMENTAL AND PUBLIC HEALTH ISSUES IN AGRICULTURE

Melvin L. Myers

As the world’s population continues to increase, demand grows for more food, but the increasing population is claiming more arable land for non-agricultural uses. Agriculturists need options to feed the world’s growing population. These options include augmenting output per hectare, developing unused land into farmland and reducing or stopping the destruction of existing farmland. Over the past 25 years, the world has seen a “green revolution”, particularly in North America and Asia. This revolution resulted in a tremendous increase in food production, and it was stimulated by developing new, more productive genetic strains and increasing inputs of fertilizer, pesticides and automation. The equation for producing more food is confounded by the need to address several environmental and public health issues. These issues include the need to prevent pollution and soil depletion, new ways to control pests, making farming sustainable, abating child labour and eliminating illicit drug cultivation.

Water and Conservation

Water pollution may be the most widespread environmental problem caused by agriculture. Agriculture is a large contributor to nonpoint pollution of surface water, including sediments, salts, fertilizers and pesticides. Sediment runoff results in soil erosion, a loss to agricultural production. Replacing 2.5 cm of topsoil naturally from bedrock and surface material takes between 200 and 1,000 years, a long time in human terms.

Sediment loading of rivers, streams, lakes and estuaries increases water turbidity, which results in decreased light for submerged aquatic vegetation. Species that depend upon this vegetation can thus experience a decline. Sediment also causes deposition in waterways and reservoirs, which adds to dredging expense and reduces water storage capacity of water supplies, irrigation systems and hydroelectric plants. Fertilizer waste, both synthetic and natural, contributes phosphorus and nitrates to the water. Nutrient loading stimulates algal growth, which can lead to eutrophication of lakes and related reduction in fish populations. Pesticides, particularly herbicides, contaminate surface water, and conventional water treatment systems are ineffective at removing them from water downstream. Pesticides contaminate food, water and feed. Groundwater is a source of drinking water for many people, and it is also contaminated with pesticides and nitrate from fertilizers. Groundwater is also used for animals and irrigation.

Irrigation has made farming possible in places where intensive farming was previously impossible, but irrigation has its negative consequences. Aquifers are depleted in places where groundwater use exceeds recharging; aquifer depletion can also lead to land subsidence. In arid areas, irrigation has been associated with mineralization and salinization of soils and water, and it has also depleted rivers. More efficient use and conservation of water can help alleviate these problems (NRC 1989).

Pest Control

Following the Second World War, the use of synthetic organic pesticides—fumigants, insecticides, herbicides and fungicides—grew dramatically, but a plethora of problems has resulted from the use of these chemicals. Growers saw the success of broad-spectrum, synthetic pesticides as a solution to pest problems that had plagued agriculture from its beginning. Not only did problems with human health effects emerge, but environmental scientists recognized ecological damage as extensive. For example, chlorinated hydrocarbons are persistent in soil and bioaccumulate in fish, shellfish and birds. The body burden of these hydrocarbons has declined in these animals where communities have eliminated or reduced chlorinated hydrocarbon use.

Pesticide applications have adversely affected non-targeted species. In addition, pests can become resistant to the pesticides, and examples of resistant species that became more virulent crop predators are numerous. Thus, growers need other approaches for pest control. Integrated pest management is an approach aimed at putting pest control on a sound ecological basis. It integrates chemical control in a way that is least disruptive to biological control. It aims, not to eliminate a pest, but to control the pest to a level that avoids economic damage (NRC 1989).

Genetically engineered crops are increasing in use (see table 64.20), but in addition to a positive result, they have a negative consequence. An example of a positive result is a genetically engineered strain of insect-resistant cotton. This strain, now in use in the United States, requires only one application of insecticide as contrasted with the five or six applications that would have been typical. The plant generates its own pesticide, and this reduces cost and environmental contamination. The potential negative consequence of this technology is the pest’s developing resistance to the pesticide. When a small number of pests survive the engineered pesticide, they can grow resistant to it. The more virulent pest can then survive the engineered pesticide and similar synthetic pesticides. Thus, the pest problem can magnify beyond the one crop to other crops. The cotton boll weevil is now controlled in this way through an engineered cotton strain. With the emergence of a resistant boll weevil, another 200 crops can fall victim to the weevil, which would no longer be susceptible to the pesticide (Toner 1996).

Table 64.20 Genetically engineered crops

Crop

Varieties

Cotton

Three varieties, incorporating insect and herbicide resistance

Corn

Two varieties, incorporating insect resistance

Soybeans

One variety, with herbicide resistance

Potatoes

One variety, incorporating insect resistance

Tomatoes

Five varieties, with delayed ripening traits, thicker skin

Squash

One variety, resistant to two viruses

Canola

One variety, engineered to produce oil rich in lauric acid

Source: Toner 1996.

Sustainable Farming

Because of environmental and economic concerns, farmers have started using alternative approaches to farming to reduce input costs, preserve resources and protect human health. The alternative systems emphasize management, biological relationships and natural processes.

In 1987, the World Commission on Environment and Development defined sustainable development to meet “the needs and aspirations of the present without compromising the ability of future generations to meet their own needs” (Myers 1992). A sustainable farm, in the broadest sense, produces adequate amounts of high-quality food, protects its resources, and is both environmentally safe and profitable. It addresses risks to human health using a systems-level approach. The concept of sustainable agriculture incorporates the term farm safety across the entire workplace environment. It includes the availability and the appropriate use of all our resources including soil, water, fertilizers, pesticides, the buildings on our farms, the animals, capital and credit, and the people who are part of the agricultural community.

Child and Migrant Labour

Children labour in agriculture throughout the world. The industrialized world in no exception. Of the 2 million children under age 19 who reside on United States farms and ranches, an estimated 100,000 are injured each year in incidents related to production agriculture. They are typically children of either farmers or farm employees (National Committee for Childhood Agricultural Injury Prevention 1996). Agriculture is one of the few occupational settings in both developed and developing countries where children can engage in work typically done by adults. Children are also exposed to hazards when they accompany their parents during work and during leisure-time visits to the farm. The primary agents of farm injuries are tractors, farm machinery, livestock, building structures and falls. Children are also exposed to pesticides, fuels, noxious gases, airborne irritants, noise, vibration, zoonoses and stress. Child labour is employed on plantations around the world. Children work with their parents as part of a team for task-based compensation on plantations and as migrant farmworkers, or they are employed directly for special plantation jobs (ILO 1994).

Some of the problems and conditions of the migrant labour and child workforce as discussed elsewhere in this chapter and in this Encyclopaedia.

Illicit Drug Crops

Some crops do not appear in official records because they are illicit. These crops are cultivated to produce narcotics for human consumption, which alter judgement, are addictive and can cause death. Moreover, they add to the loss of productive land for food production. These crops comprise the poppy (used to make opium and heroine), coca leaf (used to make cocaine and crack) and cannabis (used to produce marijuana). Since 1987, world production of the opium poppy and coca has increased, and cultivation of cannabis has decreased, as shown in table 64.21. Five links are involved in the farm-to-user chain in the illicit drug trade: cultivation, processing, transit, wholesale distribution and retail sale. To interdict the supply of illicit drugs, governments concentrate on eradicating the production of the drugs. For example, eliminating 200 hectares of coca can deprive the drug market of about one metric ton of finished cocaine for a period of 2 years, since that is how long it would take to grow back mature plants. The most efficient means for eliminating the crops is through aerial application of herbicides, although some governments resist this measure. Manual eradication is another option, but it exposes personnel to violent reaction from the growers (US Department of State 1996). Some of these crops have a legal use, such as the manufacture of morphine and codeine from opium, and exposure to their dusts can lead to narcotic hazards in the workplace (Klincewicz et al. 1990).

Table 64.21 Illicit drug cultivation, 1987, 1991 and 1995

Crop

Product

Hectares cultivated

   

 

 

1987

1991

1995

Opium poppy

Opiates

112,585

226,330

234,214

Coca (leaf)

Cocaine

175,210

206,240

214,800

Cannabis

Marijuana

  24,423

  20,919

  12,205

Source: US Department of State 1996.

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