Monday, 28 March 2011 19:08

Animal Husbandry

Written by
Rate this item
(1 Vote)

Animal husbandry—the rearing and use of animals—involves a wide variety of activities, including breeding, feeding, moving animals from one location to another, basic care (e.g., hoof care, cleaning, vaccinations), care for injured animals (either by animal handlers or veterinarians) and activities associated with particular animals (e.g., milking of cows, shearing of sheep, working with draught animals).

Such handling of livestock is associated with a variety of injuries and illnesses among humans. These injuries and illnesses may be due to direct exposure or may be due to environmental contamination from animals. The risk of injury and illness is dependent largely on the type of livestock. The risk of injury also depends on the particulars of animal behaviour (see also the articles in this chapter on specific animals). In addition, persons associated with animal husbandry are often more likely to consume products from the animals. Finally, the specific exposures depend on methods of handling livestock, which have emerged from geographical and social factors that vary across human society.

Hazards and Precautions

Ergonomic Risks

Personnel who work with cattle often have to stand, reach, bend or exert physical effort in sustained or unusual positions. Livestock workers do have an increased risk of joint pain of the back, hips and knees. There are several activities that place the livestock worker at ergonomic risk. For example, assisting with birthing of a large animal may put the farmworker in an unusual and strained position, whereas with a small animal, the worker may be required to work or lie in an inclement environment. Further, the worker may be injured by assisting animals who are ill and whose behaviour cannot be anticipated. More commonly, joint and back pain have to do with a repetitive motion, such as milking, during which the worker may crouch or kneel repeatedly.

Other cumulative trauma diseases are recognized in farmworkers, particularly livestock workers. These may be due to repetitive motion or frequent small injuries.

Solutions to reduce ergonomic risk include intensified educational efforts focused upon appropriate handling of animals, as well as engineering efforts to redesign the work environment and its tasks to accommodate animal and human factors.

Injuries

Animals are commonly recognized as agents of injury in surveys of injuries associated with agriculture. There are several postulated explanations for these observations. Close association between the worker and the animal, which often has unpredictable behaviour, puts the livestock worker at risk. Many livestock have superior size and strength. Injuries are often due to direct trauma from kicking, biting or crushing against a structure and often involve the worker’s lower extremity. The behaviour of workers may also contribute to risk of injury. Workers who penetrate the “flight zone” of livestock or who position themselves in livestock “blind spots” are at increased risk of injury resulting from flight reaction, butting, kicking and crushing.

Figure 1. Panoramic vision of cattle

LIV140F1

Women and children are over-represented among injured livestock workers. This may be due to societal factors resulting in women and children doing more of the animal-related work, or it may be due to exaggerated size differences between the animals and worker or, in the case of children, use of handling techniques to which livestock are unaccustomed.

Specific interventions to prevent animal-associated injuries include intense educational efforts, selecting animals that are more compatible with humans, selecting workers who are less likely to agitate animals and engineering approaches that                                                                                                                                 decrease the risk of exposure of humans to animals.

Zoonotic Diseases

Livestock rearing requires close association of workers and animals. Humans may become infected by organisms normally present on animals, which are rarely human pathogens. In addition, the tissues and behaviour associated with infected animals may expose workers who would experience few, if any, exposures if they were working with healthy livestock.

The relevant zoonotic diseases include numerous viruses, bacteria, mycobacteria, fungi and parasites (see table 1). Many zoonotic diseases, such as anthrax, tinea capitis or orf, are associated with skin contamination. In addition, contamination resulting from exposure to a diseased animal is a risk factor for rabies and tularaemia. Because livestock workers often are more likely to ingest under-treated animal products, such workers are at risk of diseases such as Campylobacter, cryptosporidiosis, salmonellosis, trichinosis or tuberculosis.

Table 1. Zoonotic diseases of livestock handlers

Disease

Agent

Animal

Exposure

Anthrax

Bacteria

Goats, other herbivores

Handling hair, bone or other tissues

Brucellosis

Bacteria

Cattle, swine, goats, sheep

Contact with placenta and other contaminated tissues

Campylobacter

Bacteria

Poultry, cattle

Ingestion of contaminated food, water, milk

Cryptosporidiosis

Parasite

Poultry, cattle, sheep, small mammals

Ingestion of animal faeces

Leptospirosis

Bacteria

Wild animals, swine, cattle, dogs

Contaminated water on open skin

Orf

Virus

Sheep, goats

Direct contact with mucous membranes

Psittacosis

Chlamydia

Parakeets, poultry, pigeons

Inhaled desiccated droppings

Q fever

Rickettsia

Cattle, goats, sheep

Inhaled dust from contaminated tissues

Rabies

Virus

Wild carnivores, dogs, cats, livestock

Exposure of virus-laden saliva to breaks in skin

Salmonellosis

Bacteria

Poultry, swine, cattle

Ingestion of food from contaminated organisms

Tinea capitis

Fungus

Dogs, cats, cattle

Direct contact

Trichinosis

Roundworm

Swine, dogs, cats, horses

Eating poorly cooked flesh

Tuberculosis, bovine

Mycobacteria

Cattle, swine

Ingestion of unpasteurized milk; inhalation of airborne droplets

Tularaemia

Bacteria

Wild animals, swine, dogs

Inoculation from contaminated water or flesh

 

The control of zoonotic diseases must focus on the route and source of exposure. Elimination of the source and/or interruption of the route are essential to disease control. For example, there must be proper disposal of the carcasses of diseased animals. Often, the human disease can be prevented by eliminating the disease in animals. Additionally, there should be adequate processing of animal products or tissues before use in the human food chain.

Some zoonotic diseases are treated in the livestock worker with antibiotics. However, routine prophylactic antibiotic usage on livestock may cause emergence of resistant organisms of general public health concern.

Blacksmithing

Blacksmithing (farrier work) involves primarily musculoskeletal and environmental injury. The manipulation of metal to be used in animal care, such as for horseshoes, does demand heavy work requiring substantial muscle activity to prepare the metal and position animal legs or feet. Furthermore, applying the created product, such as a horseshoe, to the animal in farrier work is an additional source of injury (see figure 2).

Figure 2. Blacksmith shoeing a horse in Switzerland

LIV110F1

Often, the heat required to bend metal involves exposure to noxious gases. A recognized syndrome, metal fume fever, has a clinical picture similar to pulmonary infection and results from inhalation of fumes of nickel, magnesium, copper or other metals.

Adverse health effects associated with blacksmithing can be alleviated by working with adequate respiratory protection. Such respiratory devices include respirators or powered air-purifying respirators with cartridges and pre-filters capable of filtering acid gas/organic vapours and metal fumes. If the farrier work occurs in a fixed location, local exhaust ventilation should be installed for the forge. Engineering controls, which place distance or barricades between the animal and the worker, will reduce the risk of injury.

Animal Allergies

All animals possess antigens which are non-human and could therefore serve as potential allergens. In addition, livestock are often hosts for mites. Since there are a large number of potential animal allergies, recognition of a specific allergen requires careful and thorough disease and occupational histories. Even with such data, recognition of a specific allergen may be difficult.

The clinical expression of animal allergies may include an anaphylaxis-type picture, with hives, swelling, nasal discharge and asthma. In some patients, itching and nasal discharge may be the only symptoms.

Controlling exposure to animal allergies is a formidable task. Improved practices in animal husbandry and changes in livestock facility ventilation systems may make it less likely that the livestock handler will be exposed. However, there may be little that can be done, other than desensitization, to prevent the formation of specific allergens. In general, desensitizing a worker can be performed only if the specific allergen is adequately characterized.

 

Back

Additional Info

Read 4976 times Last modified on Thursday, 27 October 2011 21:30

" DISCLAIMER: The ILO does not take responsibility for content presented on this web portal that is presented in any language other than English, which is the language used for the initial production and peer-review of original content. Certain statistics have not been updated since the production of the 4th edition of the Encyclopaedia (1998)."

Contents

Preface
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
Beverage Industry
Fishing
Food Industry
Forestry
Hunting
Livestock Rearing
Lumber
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

Livestock Rearing References

Aldhous, P. 1996. Scrapie theory fed BSE complacency, now fears grow for unborn babies. New Scientist 150:4-5.

Ahlgren, GH. 1956. Forage Crops. New York: McGraw-Hill Book Co.

American Conference of Governmental Industrial Hygienists (ACGIH). 1994. Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. Cincinnati, OH: ACGIH.

Auty, JH. 1983. Draught animal power in Australia. Asian Livestock VIII:83-84.

Banwart, WC and JM Brenner. 1975. Identification of sulfur gases evolved from animal manures. J Environ Qual 4:363-366.

Baxter, PJ. 1991. Toxic marine and freshwater algae: An occupational hazard? Br J Ind Med 48(8):505-506.

Bell, RG, DB Wilson, and EJ Dew. 1976. Feedlot manure top dressing for irrigated pasture: Good agricultural practice or a health hazard? B Environ Contam Tox 16:536-540.

Benenson, AS. 1990. Control of Communicable Diseases in Man. Washington, DC: American Public Health Association.

—. 1995. Control of Communicable Diseases Manual. Washington, DC: American Public Health Association.

Brown, LR. 1995. Meat production takes a leap. In Vital Signs 1995: The Trends that are Shaping our Future, edited by LR Brown, N Lenssen, and H Kane. New York: WW Norton & Company.

Bursey, RG. 1992. New uses of dairy products. In New Crops, New Uses, New Markets: Industrial and Commercial Products from U.S. Agriculture: 1992 Yearbook of Agriculture. Washington, DC: USDA.

Calandruccio, RA and JH Powers. 1949. Farm accidents: A clinical and statistical study covering twenty years. Am Surg (November):652-660.

Cameron, D and C Bishop. 1992. Farm accidents in adults. Br Med J 305:25-26.

Caras, RA. 1996. A Perfect Harmony: The Intertwining Lives of Animals and Humans throughout History. New York: Simon & Schuster.

Carstensen, O, J Lauritsen, and K Rasmussen. 1995. The West-Justland study on prevention of farm accidens, Phase 1: A study of work specific factors in 257 hospital-treated agricultural injuries. Journal of Agricultural Safety and Health 1:231-239.

Chatterjee, A, D Chattopadhyay, D Bhattacharya, Ak Dutta, and DN Sen Gupta. 1980. Some epidemiologic aspects of zoophilic dermatophytosis. International Journal of Zoonoses 7(1):19-33.

Cherry, JP, SH Fearirheller, TA Foglis, GJ Piazza, G Maerker, JH Woychik, and M Komanowski. 1992. Innovative uses of animal byproducts. In New Crops, New Uses, New Markets: Industrial and Commercial Products from U.S. Agriculture: 1992 Yearbook of Agriculture. Washington, DC: USDA.

Crowley, M. 1995. Aquaculture trends and technology. National Fisherman 76:18-19.

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

DeFoliart, GR. 1992. Insects as human foods. Crop Protection 11:395-399.

Donham, KJ. 1985. Zoonotic diseases of occupational significance in agriculture: A review. International Journal of Zoonoses 12:163-191.

—. 1986. Hazardous agents in agricultural dusts and methods of evaluation. Am J Ind Med 10:205-220.

Donham, KJ and LW Knapp. 1982. Acute toxic exposure to gases from liquid manure. J Occup Med 24:142-145

Donham, KJ and SJ Reynolds. 1995. Respiratory dysfunction in swine production workers: Dose-response relationship of environmental exposures and pulmonary function. Am J Ind Med 27:405-418.

Donham, KJ and L Scallon. 1985. Characterization of dusts collected from swine confinement buildings. Am Ind Hyg Assoc J 46:658-661.

Donham, KJ and KM Thu. 1995. Agriculture medicine and enivronmental health: The missing component of the sustainable agricultural movement. 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.

Donham, KJ, MJ Rubino, TD Thedell and J Kammenmeyer. 1977. Potential health hazards of workers in swine confinement buildings. J Occup Med 19:383-387.

Donham, KJ, J Yeggy, and RR Dauge. 1985. Chemical and physical parameters of liquid manure from swine confinement facilities: Health implications for workers, swine and the environment. Agricultural Wastes 14:97-113.

—. 1988. Production rates of toxic gases from liquid manure: Health implications for workers and animals in swine buildings. Bio Wastes 24:161-173.

Donham, KJ, DC Zavala, and JA Merchant. 1984. Acute effects of work environment on pulmonary functions of swine confinement workers. Am J Ind Med 5:367-375.

Dosman, JA, BL Graham, D Hall, P Pahwa, H McDuffie, M Lucewicz, and T To. 1988. Respiratory symptoms and alterations in pulmonary function tests in swine producers in Saskatchewan: Results of a survey of farmers. J Occ Med 30:715-720.

Douglas, JDM. 1995. Salmon farming: Occupational health in a new rural industry. Occup Med 45:89-92.

Douglas, JDM and AH Milne. 1991. Decompression sickness in fish farm workers: A new occupational hazard. Br Med J 302:1244-1245.

Durning, AT and HB Brough. 1992. Reforming the livestock economy. In State of the World, edited by LR Brown. London: WW Norton & Company.

Erlich, SM, TR Driscoll, JE Harrison, MS Frommer, and J Leight. 1993. Work-related agricultural fatalities in Australia, 1982-1984. Scand J Work Environ Health 19:162-167.

Feddes, JJR and EM Barber. 1994. Agricultural engineering solutions to problems of air contaminants in farm silos and animal buildings. 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.

Ferguson, IR and LRC Path. 1993. Rats, fish and Weil’s disease. Safety and Health Practitioner :12-16.

Food and Agriculture Organization (FAO) of the United Nations. 1965. Farm Implements for Arid and Tropical Regions. Rome: FAO.

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

Fretz, P. 1989. Injuries from farm animals. In Principles of Health and Safety in Agriculture, edited by JA Dosman and DW Crockcroft. Boca Raton, FL: CRC Press.

Froehlich, PA. 1995. Engineering Control Observations and Recommendations for Insect Rearing Facilities. Cincinnati, OH: NIOSH.

Gillespie, JR. 1997. Modern Livestock and Poultry Production. New York: Delmar Publishers.

Gorhe, DS. 1983. Draught animal power vs mechanization. Asian Livestock VIII:90-91.

Haglind, M and R Rylander. 1987. Occupational exposure and lung function measurements among workers in swine confinement buildings. J Occup Med 29:904-907.

Harries, MG and O Cromwell. 1982.Occupational allergy caused by allergy to pig’s urine. Br Med J 284:867.

Heederick, D, R Brouwer, K Biersteker, and J. Boleij. Relationship of airborne endotoxin and bacteria levels in pig farms with lung function and respiratory symptoms of farmers. Intl Arch Occup Health 62:595-601.

Hogan, DJ and P Lane. 1986. Dermatologic disorders in agriculture. Occup Med: State Art Rev 1:285-300.

Holness, DL, EL O’Glenis, A Sass-Kortsak, C Pilger, and J Nethercott. 1987. Respiratory effects and dust exposures in hog confinement farming. Am J Ind Med 11:571-580.

Holness, DL and JR Nethercott. 1994. Acute and chronic trauma in hog farmers. 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.

Iowa Department of Public Health. 1995. Sentinel Project Research Agricultural Injury Notification System. Des Moines, IA: Iowa Department of Public Health.

Iverson, M, R Dahl, J. Korsgaard, T Hallas, and EJ Jensen. 1988. Respiratory symptoms in Danish farmers: An epidemiological study of risk factors. Thorax 48:872-877.

Johnson, SA. 1982. Silkworms. Minneapolis, MN: Lerner Publications.

Jones, W, K Morring, SA Olenchock, T Williams, and J. Hickey. 1984. Environmental study of poultry confinement buildings. Am Ind Hyg Assoc J 45:760-766.

Joshi, DD. 1983. Draught animal power for food production in Nepal. Asian Livestock VIII:86-87.

Ker, A. 1995. Farming Systems in the African Savanna. Ottawa,Canada: IDRC Books.

Khan, MH. 1983. Animal as power source in Asian agriculture. Asian Livestock VIII:78-79.

Kiefer, M. 1996. Florida Department of Agriculture and Consumer Services Division of Plant Industry, Gainesville, Florida. Cincinnati, OH: NIOSH.

Knoblauch, A, B Steiner, S Bachmann, G Trachsler, R Burgheer, and J Osterwalder. 1996. Accidents related to manure in eastern Switzerland: An epidemiological study. Occup Environ Med 53:577-582.

Kok, R, K Lomaliza, and US Shivhare. 1988. The design and performance of an insect farm/chemical reactor for human food production. Canadian Agricultural Engineering 30:307-317.

Kuo, C and MCM Beveridge. 1990. Mariculture: Biological and management problems, and possible engineering solutions. In Engineering for Offshore Fish Farming. London: Thomas Telford.

Layde, PM, DL Nordstrom, D Stueland, LB Wittman, MA Follen, and KA Olsen. 1996. Animal-related occupational injuries in farm residents. Journal of Agricultural Safety and Health 2:27-37.

Leistikow, B Donham, JA Merchant, and S Leonard. 1989. Assessment of U.S. poultry worker respiratory risk. Am J Ind Med 17:73-74.

Lenhart, SW. 1984. Sources of respiratory insult in the poultry processing industry. Am J Ind Med 6:89-96.

Lincoln, JM and ML Klatt. 1994. Preventing Drownings of Commercial Fishermen. Anchorage, AK: NIOSH.

MacDiarmid, SC. 1993. Risk analysis and the importation of animals and animal products. Rev Sci Tech 12:1093-1107.

Marx, J, J Twiggs, B Ault, J Merchant, and E Fernandez-Caldas. 1993. Inhaled aeroallergen and storage mite reactivity in a Wisconsin farmer nested case-control study. Am Rev Respir Dis 147:354-358.

Mathias, CGT. 1989. Epidemiology of occupational skin disease in agriculture. In Principles of Health and Safety in Aagriculture, edited by JA Dosman and DW Cockroft. Boca Raton, FL: CRC Press.

Meadows, R. 1995. Livestock legacy. Environ Health Persp 103:1096-1100.

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

Mullan, RJ and LI Murthy. 1991. Occupational sentinel health events: An up-dated list for physician recognition and public health surveillance. Am J Ind Med 19:775-799.

National Institute for Occupational Safety and Health (NIOSH). 1993. Injuries among Farm Workers in the United states. Cincinnati, OH: NIOSH.

—. 1994. Request for Assistance in Preventing Organic Dust Toxic Syndrome. Washington, DC: GPO.

National Institutes of Health (NIH). 1988. Institutional Administrator’s Manual for Laboratory Animal Care and Use. Washington, DC: GPO.

National Research Council (NRC). 1989. Alternative Agriculture: Committee on the Role of Alternative Farming Methods in Modern Production Agriculture. Washington, DC: National Academy Press.

National Safety Council. 1982. Accident Facts. Chicago, IL: National Safety Council.

—. 1985. Electrofishing. NSC data sheet I-696-85. Chicago, IL: National Safety Council.

Nesheim, MC, RE Austic, and LE Card. 1979. Poultry Production. Philadelphia, PA: Lea and Febiger.

Olenchock, S, J May, D Pratt, L Piacitelli, and J Parker. 1990. Presence of endotoxins in different agricultural environments. Am J Ind Med 18:279-284.

O’Toole, C. 1995. Alien Empire. New York: Harper Collins Publishers.

Orlic, M and RA Leng. 1992. Prelimenary Proposal to Assist Bangladesh to Improve Ruminant Livestock Productivity and Reduce Methane Emissions. Washington, DC: US Environmental Protection Agency, Global Change Division.

Panti, NK and SP Clark. 1991. Transient hazardous conditions in animal building due to manure gas release during slurry mixing. Applied Engineering in Agriculture 7:478-484.

Platt, AE. 1995. Aquaculture boosts fish catch. In Vital Signs 1995: The Trends that Are Shaping our Future, edited by LR Brown, N Lenssen, and H Kane. New York: WW Norton & Company.

Pursel, VG, CE Rexroad, and RJ Wall. 1992. Barnyard biotchnology may soon produce new medical therapeutics. In New Crops, New Uses, New Markets: Industrial and Commercial Products from U.S. Agriculture: 1992 Yearbook of Agriculture Washington, DC: USDA.

Ramaswami, NS and GL Narasimhan. 1982. A case for building up draught animal power. Kurushetra (India’s Journal for Rural Development) 30:4.

Reynolds, SJ, KJ Donham, P Whitten, JA Merchant, LF Burmeister, and WJ Popendorf. 1996. A longitudinal evaluation of dose-response relationships for environmental exposures and pulmonary function in swine production workers. Am J Ind Med 29:33-40.

Robertson, MH, IR Clarke, JD Coghlan, and ON Gill. 1981. Leptospirosis in trout farmers. Lancet: 2(8247)626-627.

Robertson, TD, SA Ribeiro, S Zodrow, and JV Breman. 1994. Assessment of Strategic Livestock Feed Supplementation as an Opportunity for Generating Income for Small Scale Dairy Producers and Reducing Methane Emissions in Bangladesh. Washington, DC: US Environmental Protection Agency.

Rylander, R. 1994. Symptoms and mechanisms: Inflammation of the lung. Am J Ind Med 25:19-24.

Rylander, R, KJ Donham, C Hjort, R Brouwer, and D Heederik. 1989. Effects of exposure to dust in swine confinement buildings: A working group report. Scand J Work Environ Health 15:309-312.

Rylander, R and N Essle. 1990. Bronchial hyperactivity among pig and dairy farmers. Am J Ind Med 17:66-69.

Rylander, R, Y Peterson, and KJ Donman. 1990. Questionnaire evaluating organic dust exposure. Am J Ind Med 17:121-128.

Rylander, R and R Jacobs. 1994. Organic Dusts: Exposure, Effects and Prevention. Chicago, IL: Lewis Publishing.
Safina, C. 1995. The world’s imperiled fish. Sci Am 272:46-53.

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

Schmidt, MJ. 1997. Working elephants. Sci Am 279:82-87.

Schmidt, JO. 1992. Allergy to venomous insects. In The Hive and the Honey Bee, edited by JM Graham. Hamilton: DaDant & Sons.

Shumacher, MJ and NB Egen. 1995. Significance of Africanized bees on public health. Arch Int Med 155:2038-2043.

Sherson, D, I Hansen, and T Sigsgaard. 1989. Occupationally related respiratory symptoms in trout-processing workers. Allergy 44:336-341.

Stem, C, DD Joshi, and M Orlic. 1995. Reducing Methane Emissions from Ruminant Livestock: Nepal prefeasibility Study. Washington, DC: US Environmental Protection Agency, Global Change Division.

Sweeten, JM. 1995. Odor measurement technology and applications: A state-of-the-art review. In Seventh International Symposium on Agricultural and Food Processing Wastes: Proceedings of the 7th International Symposium, edited by CC Ross. American Society of Agricultural Engineering.

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

Thorne, PS, KJ Donham, J Dosman, P Jagielo, JA Merchant, and S Von Essen. 1996. Occupational health. In Understanding the Impacts of Large-scale Swine Production, edited by KM Thu, D Mcmillan, and J Venzke. Iowa City, IA: University of Iowa.

Turner, F and PJ Nichols. 1995. Role of the epithelium in the response of the airways. Abstract for the 19th Cotton and Other Organic Dust Research Conference, 6-7 January, San antonio, TX.

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

US Department of Agriculture (USDA). 1992. Agricultural Waste Management Field Handbook. Washington, DC: USDA Soil Conservation Service.

—. 1996a. Livestock and Poultry: World Markets and Trade. Circular Series FL&P 1-96. Washington DC: USDA Foreign Agricultural Service.

—. 1996b. Dairy: World Markets and Trade. Circular Series FD 1-96. Washington DC: USDA Foreign Agricultural Service.

—. 1997. Poultry Production and Value, 1996 Summary. Washington, DC: National Agricultural Statistics Service.

van Hage-Hamsten, M, S Johansson, and S Hogland. 1985. Storage mite allergy is common in a farming population. Clin Allergy 15:555-564.

Vivian, J. 1986. Keeping Bees. Charlotte, VT: Williamson Publishing.

Waller, JA. 1992. Injuries to farmers and farm families in a dairy state. J Occup Med 34:414-421.

Yang, N. 1995. Research and development of buffalo draught power for farming in China. Asian Livestock XX:20-24.

Zhou, C and JM Roseman. 1995. Agriculture-related residual injuries: Prevalence, type, and associated factors among Alabama farm operators, 1990. Journal of Rural Health 11:251-258.

Zuehlke, RL, CF Mutel, and KJ Donham. 1980. Diseases of Agricultural Workers. Iowa City, IA: Department of Preventive Medicine and Environmental Health, University of Iowa.