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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 1 provides a listing of tractor hazards and how injuries occur.

Table 1. Common tractor hazards and how they occur


Type of incident

How injury occurs


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.


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.)



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 1). 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 1.  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.


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 2 gives machine hazards, descriptions of the hazards and examples of where the hazards occur on various machines.

Table 2. Common machinery hazards and where they occur




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.



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Part I. The Body
Part II. Health Care
Part III. Management & Policy
Part IV. Tools and Approaches
Part V. Psychosocial and Organizational Factors
Part VI. General Hazards
Part VII. The Environment
Part VIII. Accidents and Safety Management
Part IX. Chemicals
Part X. Industries Based on Biological Resources
Agriculture and Natural Resources Based Industries
Farming Systems
Food and Fibre Crops
Tree, Bramble and Vine Crops
Specialty Crops
Beverage Crops
Health and Environmental Issues
Beverage Industry
Food Industry
Livestock Rearing
Paper and Pulp Industry
Part XI. Industries Based on Natural Resources
Part XII. Chemical Industries
Part XIII. Manufacturing Industries
Part XIV. Textile and Apparel Industries
Part XV. Transport Industries
Part XVI. Construction
Part XVII. Services and Trade
Part XVIII. Guides

Agriculture and Natural Resources Based Industries Additional Resources

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Agriculture and Natural Resources Based Industries References

AgSafe—Coalition for Health and Safety in Agriculture. 1992. Occupational Injuries in California Agriculture 1981–1990. Berkeley, CA: University of California.

Alexandratos, N. 1995. World Agriculture: Towards 2010. An FAO Study. New York: John Wiley & Sons.

Bean, TL and TS Lawrence. 1992. Vehicles on Public Highways. National Institute for Farm Safety Paper No. 92-04.
Myrtle Beach, SC: National Institute for Farm Safety.

Bonsall, JL. 1985. Measurement of occupational exposure to pesticides. In Occupational Hazards of Pesticide Use, edited by GJ Turnbull. London: Taylor and Francis.

Boxer PA, C Burnett, and N Swanson. 1995. Suicide and occupation: A review of the literature. J Occup Med 37(4):442–452.

Bringhurst, LS, RN Byrne, and J Gershon-Cohen. 1959. Respiratory disease of mushroom workers. Farmer’s lung. JAMA 171:15–18.

Brown, LR, N Lenssen, and H Kane. 1995. Vital Signs 1995: The Trends that Are Shaping Our Future. New York: WW Norton & Company.

Bull, D. 1982. A Growing Problem: Pesticides and the Third World Poor. Washington DC: Oxfam.

Campbell, WP. 1987. The Condition of Agricultural Driveline System Shielding and Its Impact on Injuries and Fatalities. MS Thesis. West Lafayette, IN: Purdue University.

Chang, S. 1993. Mushroom biology: The impact on mushroom production and mushroom products. In Mushroom Biology and Mushroom Products, edited by S Chang, JA Buswell, and S Chiu. Hong Kong: Chinese University Press.

Christiani, DC. 1990. Occupational health in developing countries: Review of research needs. Am J Ind Med 17:393–401.

Connally LB, PA Schulte, RJ Alderfer, LM Goldenhar, GM Calvert, KE Davis-King, and WT Sanderson. 1996. Developing the National Institute for Occupational Safety and Health’s cancer control demonstration projects for farm populations. Journal of Rural Health suppl 12(4):258–264.

Cox, A, HTM Folgering, and LJLD Van Griensven. 1988. Extrinsic allergic alveolitis caused by the spores of the Oyster mushroom Pleurotus ostreatus. Eur Respir J 1:466–468.

—. 1989. Allergische Alveolitis verursacht durch Einatmung von Sporen des Pilzes Shii-take (Lentinus edodes). Atemwegs Lungenkr 15:233–234.

Dankelman, I and J Davidson. 1988. Women and Environment in the Third World: Alliance for the Future. London: Earthscan Publications.

Davies DR. 1995. Organophosphates, affective disorders, and suicide. Journal of Nutritional and Environmental Medicine 5:367–374.

Deere & Co. 1994. Farm and Ranch Safety Management. Moline, IL: Deere & Company.

Dufaut, A. 1988. Women carrying water: How it affects their health. Waterlines 6:23–25.

Eicher, LC. 1993. State Codes for Road Travel of Agricultural Machinery. American Society of Agricultural Engineering (ASAE) Paper No. 931513. St. Joseph, MI: ASAE.

Estlander T, L Kanerva and P Piirilä. 1996. Allergic dermatoses and respiratory diseases caused by decorative plants. Afr Newslttr Occup Health Saf 6(1):11–13.

Etherton, JR, JR Myers, RC Jensen, JC Russell, and RW Broddee. 1991. Agricultural machine-related deaths. Am J Public Health 81(6):776–768.

Food and Agriculture Organization (FAO) of the United Nations. 1987. African Agriculture: The Next 25 Years. Rome: FAO.

—. 1995. The State of World Fisheries and Aquaculture. Rome: FAO.

—. 1997. FAOSTAT Statistics Database (http://apps.fao.org/Default.htm). Accessed 22 January.

Forget, G. 1991. Pesticides and the third world. J Toxicol Environ Health 32:11–31.

—. 1992. Occupational health and development: An overview of the situation. IDRC Reports: Perils in the Workplace 20:4–7.

Franck IM and DM Brownstone. 1987. Harvesters. New York: Facts on File Publications.

Freivalds, A. 1984. Evaluation of the lift angle in spade work. Ergonomics 27 suppl:128–133.

Gerrits, JPG and LJLD Van Griensven. 1990. New developments in indoor composting (tunnel process). Mushroom J 205:21–29.

Gite, LP. 1991. Optimum handle height for animal drawn mould board plough. Appl Ergon 22:21–28.

Gite, LP and BG Yadav. 1990. Optimum handle height for a push-pull type manually operated dryland weeder. Ergonomics 33:1487–1494.

Glascock, LA, TL Bean, RK Wood, TG Carpenter, and RG Holmes. 1993. Characteristics of SMV Accidents. American Society of Agricultural Engineering (ASAE) Paper No. 931618. St. Joseph, MI: ASAE.

Griffin, GA. 1973. Combine Harvesting. Moline, IL: Deere & Company.

Gunderson, PD. 1995. An analysis of suicides on the farm or ranch within five north central United States, 1980 to 1988. In Agricultural Health and Safety: Workplace, Environment, Sustainability, edited by HH McDuffie, JA Dosman, KM Semchuk, SA Olenchock, and A Senthilselvan. Boca Raton, FL: CRC Press.

Hanrahan, LP, HA Anderson, LK Haskins, J Olson, K Lappe, and D Reding. 1996. Wisconsin farmer cancer mortality, 1981 to 1990: Selected malignancies. Journal of Rural Health suppl 12(4):273–277.

Hausen, BM, KH Schulz, and U Noster. 1974. Allergic disease caused by the spores of an edible fungus Pleurotus florida. Mushr Sci 9:219–225.

Horner, WE, MD Ibanez, V Liengswangwong, JE Salvaggio, and SB Lehrer. 1988. Characterization of allergens from spores of the Oyster mushroom Pleurotus ostreatus. J Allergy Clin Immunol 82:978–986.

International Labour Organization (ILO). 1994. Recent Developments in the Plantation Sector. Geneva: ILO.

International Organization for Standardization (ISO). 1985. ISO 263. Evaluation of Human Exposure to Whole-body Vibration: Part I: General Requirements. Geneva: ISO.

Jones, TH. 1978. How to Build Greenhouses, Garden Shelters, and Sheds. New York: Harper & Row.

Kelley, KA. 1996. Characteristics of flowing grain-related entrapments and suffocations with emphasis on grain transport vehicles. Journal of Agricultural Safety and Health 96(3):143–151.

Klincewicz, S, AT Fidler, G Siwinski, and A Fleeger. 1990. Health Hazard Report: Penick Corporation, Newark, New Jersey. No. HETA -87-311-2087. Cincinnati, OH: NIOSH.

Kundiev, YI. 1983. Conditions of labor in agriculture. In Occupational Diseases of Agricultural
Workers, edited by YI Kundiev and EP Krasnyu. Kiev: Zdorovye.

Loftas, T (ed.). 1995. Dimensions of Need: An Atlas of Food and Agriculture. Santa Barbara, CA: ABC-CLIO, Inc.

Makinen-Kiljunen, S, K Turjanmaa, T Palosuo, and T Reunala. 1992. Characterization of latex antigens and allergens in surgical gloves and natural rubber by immunoelectrophoretic methods. Journal Allergy Clin Immunol 90(2):230_235.

McDuffie, HH, JA Dosman, KM Semchuk, SA Olenchock, and A Senthilselvan (eds.). 1994. Agricultural Health and Safety: Workplace, Environment, Sustainability. Boca Raton, FL: CRC Press.

Merchant. JP, BA Boehlecke, G Taylor, and M Pickett-Harner (eds.). 1986. Occupational Respiratory Diseases. DHHS (NIOSH) Publication No. 86-102. Washington, DC: GPO.

Meridian Research, Inc. 1994. Occupational Safety and Health Hazards in Agriculture: A Review of the Literature. Silver Spring, MD: Meridian Research.

Meyers, JR. 1997. Injuries among Farm Workers in the United States, 1993. DHHS (NIOSH) Publication No. 97-115. Cincinnati, OH: NIOSH.

Meyers, JR and DL Hard. 1995. Work-related fatalities in the agricultural production and services sectors, 1980–1989. Am J Ind Med 27:51–63.

Miles, J. 1996. Personal communication.

Mines, R and PL Martin. 1986. A Profile of California Farmworkers. Giannini Information Series 86-2, Berkeley: University of California, Division of Agriculture and Natural Resources.

Mohan D and R Patel. 1992. Design of safer agricultural equipment: Application of ergonomics and epidemiology. Int J Ind Erg 10: 301–310.

Murphy, DJ and RC Williams. 1983. Safe Forage Harvesting. Agricultural Engineering Fact Sheet No. 21. State College, PA: Pennsylvania State University Cooperative Extension Service.

Murphy, DJ. 1992. Safety and Health for Production Agriculture. St. Joseph, MI: American Society of Agricultural Engineering.

Myers, ML. 1992. Sustainable Agriculture as a Strategy in Agricultural Safety. American Society of Agricultural Engineers (ASAE) Paper No. 928510. St. Joseph, MI: ASAE.

Nag, PK and SK Chatterjeee. 1981. Physiological reactions of female workers in Indian agricultural work. Hum Factors 23:607–614.

Nag, PK and P Dutt. 1979. Effectiveness of some simple agricultural weeders with reference to physiological responses. J Hum Ergol 8:13–21.

—. 1980. Circulo-respiratory efficiency in some agricultural work. Appl Ergon 11:81–84.

Nag, PK and CK Pradhan. 1992. Ergonomics in the hoeing operation. Int J Ind Erg 10:341–350.

Nag, PK, NC Sebastian, and MG Marlankar. 1980. Occupational workload of Indian agricultural workers. Ergonomics 23:91–102.

Nag, PK, A Goswami, SP Ashtekar, and CK Pradhan. 1988. Ergonomics in sickle operation. Appl Ergon 19:233–239.

Nakazawa, T, K Kanatani and Y Umegae. 1981. Mushroom workers lung due to the inhalation of spores of Cortinus shii-take. Jpn J Chest Dis 40:934–938.

National Committee for Childhood Agricultural Injury Prevention. 1996. Children and Agriculture: Opportunities for Safety and Health. Marshfield, WI: Marshfield Clinic.

National Research Council (NRC). 1989. Alternative Agriculture. Washington, DC: National Academy Press.

—. 1993. Sustainable Agriculture and the Environment in the Humid Tropics. Washington, DC: National Academy Press.

National Safety Council (NSC). 1942. Accident Facts. Chicago, IL: NSC.

—. 1986. Grain Harvest Safety. Chicago, IL: NSC.

—. 1993. Accident Facts. Chicago, IL: NSC.

—. 1995. Accident Facts. Chicago, IL: NSC.

Nomura, S. 1993. Studies on the work load and health management in agricultural workers. Journal of Japanese Association of Rural Medicine 42:1007–1011.

Olson, J.A. 1987. Pleurotus spores as allergens. Mushr J 172:115–117.

Organization for Economic Cooperation and Development (OECD). 1994. Farm Employment and Economic Adjustment in OECD Countries. Paris: OECD.

Parrón, T, AF Hernández, and E Villanueva. 1996. Increased risk of suicide with exposure to pesticides in an intensive agricultural area: A 12-year retrospective study. Forensic Science International 79:53–63.

Partanen, T. 1996. Improving the work environment by means of risk surveys. Afr Newslttr Occup Health Saf 6(2):28–29.

Pearce, N and JS Reif. 1990. Epidemiologic studies of cancer in agricultural workers. Am J Ind Med 18:133–148.

Pepys, J. 1967. Hypersensitivity against inhaled organic antigens. J Roy Coll Phys London 2:42–48.

Popendorf, W and KJ Donham. 1991. Agricultural hygiene. In Patty’s Industrial Hygiene and Toxicology, 4th edition, edited by GD Clayton and FE Clayton. New York: John Wiley & Sons, Inc.

Pradhan, CK, A Goswami, SK Ghosh, and PK Nag. 1986. Evaluation of working with spade in agriculture. Indian J Med Res 84:424–429.

Raffle, PAB, PH Adams, PJ Baxter, and WR Lee. 1994. Hunter’s Diseases of Occupations, 8th edition, London: Edward Arnold.

Recht, C and MF Wetterwald. 1992. Bamboos. Portland, OR: Timber Press.

Rowntree, RA. 1987. Contemplating the urban forests. In Our American Land: 1987 Yearbook of Agriculture. Washington, DC: USDA.

Rylander, R. 1986. Lung diseases caused by organic dusts in the farm environment. Am J Ind Med 10:221–227.

Sakula, A. 1967. Mushroom-worker’s lung. Brit Med J 3:708–710.

Sastre, J, MD Ibanez, M Lopez, and SB Lehrer. 1990. Respiratory and immunological reactions among Shii-take (Lentinus edodes) workers. Clin Exp Allergy 20:13–20.

Scherf, BD. 1995. World Watch List for Domestic Animal Diversity. Rome: FAO.

Sen, RN and PK Nag. 1975. Work organization of heavy load handling in India. J Hum Ergol 4:103–113.

Shutske, JM, WE Field, LD Gaultney, and SD Parsons. 1991. Agricultural machinery fire losses: A preventative approach. Applied Engineering in Agriculture 6(5):575–581.

Skillicorn, P, W Spira, and W Journet. 1993. Duckweed Aquaculture: A New Aquatic Farming System for Developing Countries. Washington, DC: World Bank.

Snyder, K and T Bobick. 1995. Safe Grain and Silage Handling. DHHS (NIOSH) Publication No. 95-109. Cincinnati, OH: NIOSH.

Sonnenberg, ASM, PCC Van Loon, and LJLD Van Griensven. 1996. Het aantal sporen dat Pleurotus
spp. in de lucht verspreidt (with an English summary). De Champignoncultuur 40:269–272.

Steinke, WE. 1991. Farm Labor, Tractor Use, and Farm Work Injury Survey. Unpublished data. Davis, CA: University of California.

Stewart, CJ. 1974. Mushroom worker’s lung—Two outbreaks. Thorax 29:252–257.

Stolz, JL, PH Arger, and JM Benson. 1976. Mushroom worker’s lung disease. Radiology 119:61–63.

Storch, G, JG Burford, RB George, L Kaufman, and L Ajello. 1980. Acute histoplasmosis: Description of an outbreak in Northern Louisiana. Chest 77(1):38–42.

Sullivan JB, M Gonzales, GR Krieger, and CF Runge. 1992. Health-related hazards of agriculture. In Hazardous Material Toxicology: Clinical Principles of Environmental Health, edited by JB Sullivan and GR Kreiger. London: Williams & Wilkins.

Tannahill, R. 1973. Food in History. New York: Stein and Day.

Toner, M. 1996. Debugging king cotton. Atlanta Journal-Constitution 47(50):G1.

United Nations Development Programme (UNDP). 1996. Urban Agriculture: Food, Jobs, and Sustainable Cities. New York: UNDP.

US Department of Agriculture (USDA). 1996. Foreign Agricultural Service Circular Series FTROP 2-96. Washington, DC: USDA.

US Department of Labor (DOL). 1968. Fair Labor Standards Act—The Hazardous Occupations Order for Agriculture. Washington, DC: US DOL.

US Department of State. 1996. International Narcotics Control Report. Washington, DC: US Department of State.

Van den Bogart, HGG. 1990. De champignonkwekerslong: een onderzoek naar voorkomen en etiologie in Nederland. PhD dissertation. Nijmegen, Netherlands: University of Nijmegen.

Van den Bogart, HGG, G Van den Ende, PGG Van Loon, and LJLD Van Griensven. 1993. Mushroom worker’s lung: serologic reactions to thermophilic actinomycetes in the air of compost tunnels. Mycopathologia 122:21–28.

Van Haaren, JPM. 1988. Occupational diseases. In The Cultivation of Mushrooms, edited by LJLD Van Griensven. Rustington, UK: Darlington Mushroom Laboratories.

Van Loon, PCC, AL Cox, OPJM Wuisman, SLGE Burgers, and LJLD Van Griensven. 1992. Mushroom worker’s lung. Detection of antibodies against shii take (Lentinus edodes) spore antigens in shii take workers. J Occup Med 34:1097–1101.

Villarejo, D. 1995. Issues for farm employees in the United States. In Agricultural Health and Safety: Workplace, Environment and Sustainability, edited by HH McDuffie, JA Dosman, KM Semchulk, SA Olenchock, and A Senthilselvan. Boca Raton, FL: CRC Press.

Viten VPh, EP Krashyyuh, and OV Ilyna. 1994. Ergonomic and health aspects of pesticide exposure in greenhouses. In Health, Safety and Ergonomic Aspects in Use of Chemicals in Agriculture and Forestry: Proceedings of the XII Joint GIGR; IAAMRH, IUFRP International Symposium, edited by Y Kundiev. Kiev: Institute for Occupational Health.

Wallerstein N and M Weinger. 1992. Health and safety education for worker empowerment. Am J Ind Med 22:619–635.

Weinger, J and M Lyons. 1992. Problem-solving in the fields: An action-oriented approach to farmworker education about pesticides. Am J Ind Med 22:677–690.

Weinger, M and N Wallerstein. 1990. Education for action: An innovative approach to training hospital employees. In Essentials of Modern Hospital Safety, edited by W Charney and J Whirmer. Chelsea, MI: Lewis Publishers.

Zejda. JE, HH McDuffie, and JA Dosman. 1993. Epidemiology of health and safety risks in agriculture and related industries: Practical applications for rural physicians. West J Med 158:56–63.