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64. Agriculture and Natural Resources Based Industries

64. Agriculture and Natural Resources Based Industries (34)

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64. Agriculture and Natural Resources Based Industries

Chapter Editor: Melvin L. Myers

Table of Contents

Tables and Figures

General Profile
Melvin L. Myers

     Case Study: Family Farms
     Ted Scharf, David E. Baker and Joyce Salg

Farming  Systems

Melvin L. Myers and I.T. Cabrera

Migrant and Seasonal Farmworkers
Marc B. Schenker

Urban Agriculture
Melvin L. Myers

Greenhouse and Nursery Operations
Mark M. Methner and John A. Miles

Samuel H. Henao

Farmworker Education about Pesticides: A Case Study
Merri Weinger

Planting and Growing Operations
Yuri Kundiev and V.I. Chernyuk

Harvesting Operations
William E. Field

Storing and Transportation Operations
Thomas L. Bean

Manual Operations in Farming
Pranab Kumar Nag

Dennis Murphy

     Case Study: Agricultural Machinery
     L. W. Knapp, Jr.

Food  and Fibre Crops

Malinee Wongphanich

Agricultural Grains and Oilseeds
Charles Schwab

Sugar Cane Cultivation and Processing
R.A. Munoz, E.A. Suchman, J.M. Baztarrica and Carol J. Lehtola

Potato Harvesting
Steven Johnson

Vegetables and Melons
B.H. Xu and Toshio Matsushita   

Tree,  Bramble and Vine Crops

Berries and Grapes
William E. Steinke

Orchard Crops
Melvin L. Myers

Tropical Tree and Palm Crops
Melvin L. Myers

Bark and Sap Production
Melvin L. Myers

Bamboo and Cane
Melvin L. Myers and Y.C. Ko

Specialty  Crops

Tobacco Cultivation
Gerald F. Peedin

Ginseng, Mint and Other Herbs
Larry J. Chapman

L.J.L.D. Van Griensven

Aquatic Plants
Melvin L. Myers and J.W.G. Lund

Beverage Crops

Coffee Cultivation
Jorge da Rocha Gomes and Bernardo Bedrikow

Tea Cultivation
L.V.R. Fernando

Thomas Karsky and William B. Symons

Health  and Environmental Issues

Health Problems and Disease Patterns in Agriculture
Melvin L. Myers

     Case Study: Agromedicine
     Stanley H. Schuman and Jere A. Brittain

Environmental and Public Health Issues in Agriculture
Melvin L. Myers


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1. Sources of nutrients
2. Ten steps for a plantation work risk survey
3. Farming systems in urban areas
4. Safety advice for lawn & garden equipment
5. Categorization of farm activities
6. Common tractor hazards & how they occur
7. Common machinery hazards & where they occur
8. Safety precautions
9. Tropical & subtropical trees, fruits & palms
10. Palm products
11. Bark & sap products & uses
12. Respiratory hazards
13. Dermatological hazards
14. Toxic & neoplastic hazards
15. Injury hazards
16. Lost time injuries, United States, 1993
17. Mechanical & thermal stress hazards
18. Behavioural hazards
19. Comparison of two agromedicine programmes
20. Genetically engineered crops
21. Illicit drug cultivation, 1987, 1991 & 1995


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65. Beverage Industry

65. Beverage Industry (10)

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65. Beverage Industry

Chapter Editor: Lance A. Ward

Table of Contents

Tables and Figures

General Profile
David Franson

Soft Drink Concentrate Manufacturing
Zaida Colon

Soft Drink Bottling and Canning
Matthew Hirsheimer

Coffee Industry
Jorge da Rocha Gomes and Bernardo Bedrikow

Tea Industry
Lou Piombino

Distilled Spirits Industry
R.G. Aldi and Rita Seguin

Wine Industry
Alvaro Durao

Brewing Industry
J.F. Eustace

Health and Environmental Concerns
Lance A. Ward


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1. Selected coffee importers (in tonnes)


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66. Fishing

66. Fishing (10)

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66. Fishing

Chapter Editors: Hulda Ólafsdóttir and Vilhjálmur Rafnsson

Table of Contents

Tables and Figures

General Profile
Ragnar Arnason

     Case Study: Indigenous Divers
     David Gold

Major Sectors and Processes
Hjálmar R. Bárdarson

Psychosocial Characteristics of the Workforce at Sea
Eva Munk-Madsen

     Case Study: Fishing Women

Psychosocial Characteristics of the Workforce in On-Shore Fish Processing
Marit Husmo

Social Effects of One-Industry Fishery Villages
Barbara Neis

Health Problems and Disease Patterns
Vilhjálmur Rafnsson

Musculoskeletal Disorders Among Fishermen and Workers in the Fish Processing Industry
Hulda Ólafsdóttir

Commercial Fisheries: Environmental and Public Health Issues
Bruce McKay and Kieran Mulvaney


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1. Mortality figures on fatal injuries among fishermen
2. The most important jobs or places related to risk of injuries


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67. Food Industry

67. Food Industry (11)

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67. Food Industry

Chapter Editor: Deborah E. Berkowitz

Table of Contents

Tables and Figures

Overview and Health Effects

Food Industry Processes
M. Malagié, G. Jensen, J.C. Graham and Donald L. Smith

Health Effects and Disease Patterns
John J. Svagr

Environmental Protection and Public Health Issues
Jerry Spiegel

Food Processing Sectors

Deborah E. Berkowitz and Michael J. Fagel

Poultry Processing
Tony Ashdown

Dairy Products Industry
Marianne Smukowski and Norman Brusk

Cocoa Production and the Chocolate Industry
Anaide Vilasboas de Andrade

Grain, Grain Milling and Grain-Based Consumer Products
Thomas E. Hawkinson, James J. Collins and Gary W. Olmstead

R.F. Villard

Sugar-Beet Industry
Carol J. Lehtola

Oil and Fat
N.M. Pant


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1. The food industries, their raw materials & processes
2. Common occupational diseases in the food & drink industries
3. Types of infections reported in food & drink industries
4. Examples of uses for by-products from the food industry
5. Typical water reuse ratios for different industry sub-sectors


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68. Forestry

68. Forestry (17)

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68. Forestry

Chapter Editor: Peter Poschen

Table of Contents

Tables and Figures

General Profile
Peter Poschen

Wood Harvesting
Dennis Dykstra and Peter Poschen

Timber Transport
Olli Eeronheimo

Harvesting of Non-wood Forest Products
Rudolf Heinrich

Tree Planting
Denis Giguère

Forest Fire Management and Control
Mike Jurvélius

Physical Safety Hazards
Bengt Pontén

Physical Load
Bengt Pontén

Psychosocial Factors
Peter Poschen and Marja-Liisa Juntunen

Chemical Hazards
Juhani Kangas

Biological Hazards among Forestry Workers
Jörg Augusta

Rules, Legislation, Regulations and Codes of Forest Practices
Othmar Wettmann

Personal Protective Equipment
Eero Korhonen

Working Conditions and Safety in Forestry Work
Lucie Laflamme and Esther Cloutier

Skills and Training
Peter Poschen

Living Conditions
Elías Apud

Environmental Health Issues
Shane McMahon


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1. Forest area by region (1990)
2. Non-wood forest product categories & examples
3. Non-wood harvesting hazards & examples
4. Typical load carried while planting
5. Grouping of tree-planting accidents by body parts affected
6. Energy expenditure in forestry work
7. Chemicals used in forestry in Europe & North America in the 1980s
8. Selection of infections common in forestry
9. Personal protective equipment appropriate for forestry operations
10. Potential benefits to environmental health


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69. Hunting

69. Hunting (2)

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69. Hunting

Chapter Editor: George A. Conway

Table of Contents


A Profile of Hunting and Trapping in the 1990s
John N. Trent

Diseases Associated with Hunting and Trapping
Mary E. Brown


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1. Examples of diseases potentially significant to hunters & trappers

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70. Livestock Rearing

70. Livestock Rearing (21)

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70. Livestock Rearing

Chapter Editor: Melvin L. Myers

Table of Contents

Tables and Figures

Livestock Rearing: Its Extent and Health Effects
Melvin L. Myers

Health Problems and Disease Patterns
Kendall Thu, Craig Zwerling and Kelley Donham

     Case Study: Arthopod-related Occupational Health Problems
     Donald Barnard

Forage Crops
Lorann Stallones

Livestock Confinement
Kelley Donham

Animal Husbandry
Dean T. Stueland and Paul D. Gunderson

     Case Study: Animal Behaviour
     David L. Hard

Manure and Waste Handling
William Popendorf

     A Checklist for Livestock Rearing Safety Practice
     Melvin L. Myers

John May

Cattle, Sheep and Goats
Melvin L. Myers

Melvin L. Myers

Poultry and Egg Production
Steven W. Lenhart

     Case Study: Poultry Catching, Live Hauling and Processing
     Tony Ashdown

Horses and Other Equines
Lynn Barroby

     Case Study: Elephants
     Melvin L. Myers

Draught Animals in Asia
D.D. Joshi

Bull Raising
David L. Hard

Pet, Furbearer and Laboratory Animal Production
Christian E. Newcomer

Fish Farming and Aquaculture
George A. Conway and Ray RaLonde

Beekeeping, Insect Raising and Silk Production
Melvin L. Myers and Donald Barnard


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1. Livestock uses
2. International livestock production (1,000 tonnes)
3. Annual US livestock faeces & urine production
4. Types of human health problems associated with livestock
5. Primary zoonoses by world region
6. Different occupations & health & safety
7. Potential arthropod hazards in the workplace
8. Normal & allergic reactions to insect sting
9. Compounds identified in swine confinement
10. Ambient levels of various gases in swine confinement
11. Respiratory diseases associated with swine production
12. Zoonotic diseases of livestock handlers
13. Physical properties of manure
14. Some important toxicologic benchmarks for hydrogen sulphide
15. Some safety procedures related to manure spreaders
16. Types of ruminants domesticated as livestock
17. Livestock rearing processes & potential hazards
18. Respiratory illnesses from exposures on livestock farms
19. Zoonoses associated with horses
20. Normal draught power of various animals


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71. Lumber

71. Lumber (4)

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71. Lumber

Chapter Editors: Paul Demers and Kay Teschke

Table of Contents

Tables and Figures

General Profile
Paul Demers

Major Sectors and Processes: Occupational Hazards and Controls
Hugh Davies, Paul Demers, Timo Kauppinen and Kay Teschke

Disease and Injury Patterns
Paul Demers

Environmental and Public Health Issues
Kay Teschke and Anya Keefe


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1. Estimated wood production in 1990
2. Estimated production of lumber for the 10 largest world producers
3. OHS hazards by lumber industry process area


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72. Paper and Pulp Industry

72. Paper and Pulp Industry (13)

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72. Paper and Pulp Industry

Chapter Editors: Kay Teschke and Paul Demers

Table of Contents

Tables and Figures

General Profile
Kay Teschke

Major Sectors and Processes

Fibre Sources for Pulp and Paper
Anya Keefe and Kay Teschke

Wood Handling
Anya Keefe and Kay Teschke

Anya Keefe, George Astrakianakis and Judith Anderson

George Astrakianakis and Judith Anderson

Recycled Paper Operations
Dick Heederik

Sheet Production and Converting: Market Pulp, Paper, Paperboard
George Astrakianakis and Judith Anderson

Power Generation and Water Treatment
George Astrakianakis and Judith Anderson

Chemical and By-product Production
George Astrakianakis and Judith Anderson

Occupational Hazards and Controls
Kay Teschke, George Astrakianakis, Judith Anderson, Anya Keefe and Dick Heederik

Disease and Injury Patterns

Injuries and Non-malignant Diseases
Susan Kennedy and Kjell Torén

Kjell Torén and Kay Teschke

Environmental and Public Health Issues
Anya Keefe and Kay Teschke


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1. Employment & production in selected countries (1994)
2. Chemical constituents of pulp & paper fibre sources
3. Bleaching agents & their conditions of use
4. Papermaking additives
5. Potential health & safety hazards by process area
6. Studies on lung & stomach cancer, lymphoma & leukaemia
7. Suspensions & biological oxygen demand in pulping


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Arthropods comprise more than 1 million species of insects and thousands of species of ticks, mites, spiders, scorpions and centipedes. Bees, ants, wasps and scorpions sting and inject venom; mosquitoes and ticks suck blood and transmit diseases; and the scales and hairs from insect bodies can irritate the eyes and skin, as well as tissues in the nose, mouth and respiratory system. Most stings in humans are from social bees (bumble bees, honey bees). Other stings are from paper wasps, yellow jackets, hornets and ants.

Arthropods can be a health hazard in the workplace (see table 1), but in most cases, potential arthropod hazards are not unique to specific occupations. Rather, exposure to arthropods in the workplace depends on geographic location, local conditions and the time of year. Table 2 lists some of these hazards and their corresponding arthropod agents. For all arthropod hazards, the first line of defence is avoidance or exclusion of the offending agent. Venom immunotherapy may increase a person’s tolerance to arthropod venom and is accomplished by injecting increasing doses of venom over time. It is effective in 90 to 100% of venom hypersensitive individuals but involves an indefinite course of expensive injections. Table 3 lists normal and allergic reactions to insect stings.

Table 1. Different occupations and their potential for contact with arthropods that may adversely affect health and safety.



Construction personnel, environmentalists, farmers, fishers, foresters, fish and wildlife workers, naturalists, transportation workers, park rangers, utility workers

Ants, bees, biting flies, caterpillars, chiggers, centipedes, caddisflies, fly maggots, mayflies, scorpions, spiders, ticks, wasps

Cosmetics manufacturers, dock workers, dye makers, factory workers, food processors, grainery workers, homemakers, millers, restaurant workers

Ants; beetles; bean, grain and pea weevils; mites; scale insects; spiders


Ants, bumble bees, honey bees, wasps

Insect production workers, laboratory and field biologists, museum curators

Over 500 species of arthropods are reared in the laboratory. Ants, beetles, mites, moths, spiders and ticks are especially important.

Hospital and other health care workers, school administrators, teachers

Ants, beetles, biting flies, caterpillars, cockroaches, mites

Silk producers

Silk worms


Table 2. Potential arthropod hazards in the workplace and their causative agent(s)


Arthropod agents

Bites, envenomation1

Ants, biting flies, centipedes, mites, spiders

Sting envenomation, venom hypersensitivity2

Ants, bees, wasps, scorpions

Tick toxicosis/paralysis



Beetles, caddisflies, caterpillars, cockroaches, crickets, dust mites, fly maggots, grain mites, grain weevils, grasshoppers, honeybees, mayflies, moths, silk worms

Contact dermatitis3

Blister beetles, caterpillars, cockroaches, dried fruit mites, dust mites, grain mites, straw itch mites, moths, silk worms, spiders

1 Envenomation with poison from glands associated with mouthparts.

2 Envenomation with poison from glands not associated with mouthparts.

3 Includes primary irritant and allergic dermatitis.


Table 3. Normal and allergic reactions to insect sting

Type of response


I. Normal, non-allergic reactions at the time of the sting

    Pain, burning, itching, redness at the sting site, white area surrounding the sting site, swelling, tenderness

    II. Normal, non-allergic reactions
    hours or days after sting

      Itching, residual redness, small brown or red damage spot at sting site, swelling at the sting site

      III. Large local reactions

      Massive swelling around the sting site extending over an area 10 cm or more and increasing in size for 24 to 72 hours, sometimes lasting up to a week or more

      IV. Cutaneous allergic reactions

      Hives anywhere on the skin, massive swelling remote from the sting site, generalized itching of the skin, generalized redness of the skin remote from the sting site

      V.  Non life-threatening systemic
      allergic reactions

      Allergic rhinitis, minor respiratory symptoms, abdominal cramps

      VI. Life-threatening systemic allergic reactions

      Shock, unconsciousness, hypotension or fainting, difficulty in breathing, massive swelling in the throat.

      Source: Schmidt 1992.



      Monday, 28 March 2011 19:01

      Forage Crops

      As populations tended to concentrate and the need for winter feeding in northern climates grew, the need to harvest, cure and feed hay to domestic animals emerged. Although pasture dates to the earliest domestication of animals, the first cultivated forage plant may have been alfalfa, with its recorded use dating back to 490 BC in Persia and Greece.

      Livestock forage is a crucial input for livestock rearing. Forages are grown for their vegetation and not their grains or seeds. Stems, leaves and inflorescences (flower clusters) of some legumes (e.g., alfalfa and clover) and a variety of non-legume grasses are used for grazing or harvested and fed to livestock. When grain crops such as corn, sorghum or straw are harvested for their vegetation, they are considered forage crops.

      Production Processes

      The major categories of forage crops are pastures and open ranges, hay and silage. Forage crops can be harvested by livestock (in pastures) or by humans, either by hand or machinery. The crop can be used for farm feeding or for sale. In forage production, tractors are a source of traction and processing power, and, in dry areas, irrigation may be required.

      Pasture is fed by allowing the livestock to graze or browse. The type of pasture crop, typically grass, varies in its production with the season of the year, and pastures are managed for spring, summer and fall grazing. Range management focuses on not overgrazing an area, which involves rotating livestock from one area to another. Crop residues may be part of the pasture diet for livestock.

      Alfalfa, a popular hay crop, is not a good pasture crop because it causes bloating in ruminants, a condition of a gas build-up in the rumen (the first part of the cow’s stomach) that can kill a cow. In temperate climates, pastures are ineffective as a feed source in the winter, so stored feed is needed. Moreover, in large operations, harvested forage—hay and silage—is used because pasture is impractical for large concentrations of animals.

      Hay is forage that is grown and dry-cured before storage and feeding. After the hay crop has grown, it is cut with a mowing machine or swather (a machine that combines the mowing and raking operations) and raked by a machine into a long row for drying (a windrow). During these two processes it is field cured for baling. Historically harvesting was done by pitchforking loose hay, which may still be used to feed the animals. Once cured, the hay is baled. The baling machine picks up the hay from the windrow, and compresses and wraps it into either a small square bale for manual handling, or large square or round bales for mechanical handling. The small bale may be kicked mechanically from the baler back into a trailer, or it may be picked up by hand and placed—a task called bucking—onto a trailer for transport to the storage area. The bales are stored in stacks, usually under a cover (barn, shed or plastic) to protect them from rain. Wet hay can easily spoil or spontaneously combust from the heat of the decaying process. Hay may be processed for commercial use into compressed pellets or cubes. A crop can be cut several times in a season, three times being typical. When it is fed, a bale is moved to the feeding trough, opened and placed into the trough where the animal can reach it. This part of the operation is typically manual.

      Other forage that is harvested for livestock feeding is corn or sorghum for silage. The economic advantage is that corn has as much as 50% more energy when harvested as silage than grain. A machine is used to harvest most of the green plant. The crop is cut, crushed, chopped and ejected into a trailer. The material is then fed as green chop or stored in a silo, where it undergoes fermentation in the first 2 weeks. The fermentation establishes an environment that prevents spoilage. Over a year, the silo is emptied as the silage is fed to livestock. This feeding process is primarily mechanical.

      Hazards and Their Prevention

      The storage of animal feed presents health hazards for workers. Early in the storage process, nitrogen dioxide is produced and can cause serious respiratory damage and death (“silo filler’s disease”). Storage in enclosed environments, such as silos, can create this hazard, which can be avoided by not entering silos or enclosed storage spaces in the first few weeks after feed has been stored. Further problems can occur later if the alfalfa, hay, straw or other forage crop was wet when it was stored and there is a build-up of fungi and other microbial contaminants. This can result in acute respiratory illness (“silo unloader’s disease”, organic dust toxicity) and/or chronic respiratory diseases (“farmer’s lung”). The risk of acute and chronic respiratory diseases can be reduced through the use of appropriate respirators. There should also be appropriate confined space entry procedures.

      The straw and hay used for bedding is usually dry and old, but may contain moulds and spores which can cause respiratory symptoms when dust is made airborne. Dust respirators can reduce exposure to this hazard.

      Harvesting and baling equipment and bedding choppers are designed to chop, cut and mangle. They have been associated with traumatic injuries to farm workers. Many of these injuries occur when workers try to clear clogged parts while the equipment is still operating. The equipment should be turned off before clearing jams. If more than one person is working, then a lockout/tagout programme should be in effect. Another major source of injuries and fatalities is tractor overturns without proper roll-over protection for the driver (Deere & Co. 1994). More information on farm machinery hazards is also discussed elsewhere in this Encyclopaedia.

      Where animals are used to plant, harvest and store feed, there is a possibility of animal-related injuries from kicks, bites, strains, sprains, crush injuries and lacerations. Correct animal handling techniques are the most likely means to reduce these injuries.

      Manual handling of bales of hay and straw can result in ergonomic problems. Workers should be trained in correct lifting procedures, and mechanical equipment should be used where possible.

      Forage and bedding are fire hazards. Wet hay, as mentioned previously, is a spontaneous combustion hazard. Dry hay, straw and so forth will burn easily, especially when loose. Even bailed forage is a major fuel source in a fire. Basic fire precautions should be instituted, such as no-smoking rules, elimination of spark sources and fire suppression measures.



      Monday, 28 March 2011 19:04

      Livestock Confinement

      Global economic forces have contributed to the industrialization of agriculture (Donham and Thu 1995). In the developed countries, there are trends toward increased specialization, intensity and mechanization. Increased confinement production of livestock has been a result of these trends. Many developing countries have recognized the need to adopt confinement production in an attempt to transform their agriculture from a subsistence to a globally competitive enterprise. As more corporate organizations obtain ownership and control of the industry, fewer, but larger, farms with many employees replace the family farm.

      Conceptually, the confinement system applies principles of industrial mass production to livestock production. The concept of confinement production includes raising animals in high densities in structures that are isolated from the outside environment and equipped with mechanical or automated systems for ventilation, waste handling, feeding and watering (Donham, Rubino et al. 1977).

      Several European countries have been using confinement systems since the early 1950s. Livestock confinement started to appear in the United States in the late 1950s. Poultry producers were first to use the system. By the early 1960s, the swine industry had also started to adopt this technique, followed more recently by dairy and beef producers.

      Accompanying this industrialization, several worker health and social concerns have developed. In most Western countries, farms are getting fewer in number but larger in size. There are fewer family farms (combined labour and management) and more corporate structures (particularly in North America). The result is that there are more hired workers and relatively fewer family members working. Additionally, in North America, more workers are coming from minority and immigrant groups. Therefore, there is a risk of producing a new underclass of workers in some segments of the industry.

      A whole new set of occupational hazardous exposures has arisen for the agricultural worker. These can be categorized under four main headings:

      1. toxic and asphyxiating gases
      2. bioactive aerosols of particulates
      3. infectious diseases
      4. noise.


      Respiratory hazards are also a concern.

      Toxic and Asphyxiating Gases

      Several toxic and asphyxiating gases resulting from microbial degradation of animal wastes (urine and faeces) may be associated with livestock confinement. Wastes are most commonly stored in liquid form under the building, over a slatted floor or in a tank or lagoon outside the building. This manure storage system is usually anaerobic, leading to the formation of a number of toxic gases (see table 1) (Donham, Yeggy and Dauge 1988). See also the article “Manure and waste handling" in this chapter.

      Table 1. Compounds identified in swine confinement building atmospheres



      Isopropyl propionate


      Ethyl formate

      Isovaleric acid




      Acetic acid


      Methyl acetate





      Heterocylic nitrogen compound






      Hydrogen sulphide


      Butyric acid


      Propionic acid

      Carbon dioxide



      Carbon monoxide

      Isobutyl acetate

      Propyl propionate




      Diethyl sulphide

      Isobutyric acid


      Dimethyl sulphide




      Isopropyl acetate



      There are four common toxic or asphyxiating gases present in almost every operation where anaerobic digestion of wastes occurs: carbon dioxide (CO2), ammonia (NH3), hydrogen sulphide (H2S) and methane (CH4). A small amount of carbon monoxide (CO) may also be produced by the decomposing animal wastes, but its main source is heaters used to burn fossil fuels. Typical ambient levels of these gases (as well as particulates) in swine confinement buildings are shown in table 2. Also listed are maximum recommended exposures in swine buildings based on recent research (Donham and Reynolds 1995; Reynolds et al. 1996) and threshold limit values (TLVs) set by the American Conference of Governmental Industrial Hygienists (ACGIH 1994). These TLVs have been adopted as legal limits in many countries.

      Table 2. Ambient levels of various gases in swine confinement buildings


      Range (ppm)

      Typical ambient concentrations (ppm)

      Recommended maximum exposure concentrations (ppm)

      Threshold limit values (ppm)


      0 to 200





      1,000 to 10,000





      5 to 200





      0 to 1,500




      Total dust

      2 to 15 mg/m3

      4 mg/m3

      2.5 mg/m3

      10 mg/m3

      Respirable dust

      0.10 to 1.0 mg/m3

      0.4 mg/m3

      0.23 mg/m3

      3 mg/m3


      50 to 500 ng/m3

      200 ng/m3

      100 ng/m3

      (none established)


      It can be seen that in many of the buildings, at least one gas, and often several, exceeds the exposure limits. It should be noted that simultaneous exposure to these toxic substances may be additive or synergistic—the TLV for the mixture may be exceeded even when individual TLVs are not exceeded. Concentrations are often higher in the winter than in the summer, because ventilation is reduced to conserve heat.

      These gases have been implicated in several acute conditions in workers. H2S has been implicated in many sudden animal deaths and several human deaths (Donham and Knapp 1982). Most acute cases have occurred shortly after the manure pit has been agitated or emptied, which may result in a sudden release of a large volume of the acutely toxic H2S. In other fatal cases, manure pits had recently been emptied, and workers who entered the pit for inspection, repairs or to retrieve a dropped object collapsed without any forewarning. The available post-mortem results of these cases of acute poisoning revealed massive pulmonary oedema as the only notable finding. This lesion, combined with the history, is compatible with hydrogen sulphide intoxication. Rescue attempts by bystanders have often resulted in multiple fatalities. Confinement workers should therefore be informed of the risks involved and advised never to enter a manure storage facility without testing for the presence of toxic gases, being equipped with a respirator with its own oxygen supply, ensuring adequate ventilation and having at least two other workers stand by, attached by a rope to the worker who enters, so they can effect a rescue without endangering themselves. There should be a written confined-space programme.

      CO may also be present at acute toxic levels. Abortion problems in swine at an atmospheric concentration of 200 to 400 ppm and subacute symptoms in humans, such as chronic headache and nausea, have been documented in swine confinement systems. The possible effects on the human foetus should also be of concern. The primary source of CO is from improperly functioning hydrocarbon-burning heating units. Heavy accumulation of dust in swine confinement buildings makes it difficult to keep heaters in correct working order. Propane-fuelled radiant heaters are also a common source of lower levels of CO (e.g., 100 to 300 ppm). High-pressure washers powered by an internal combustion engine that may be run inside the building are another source; CO alarms should be installed.

      Another acutely dangerous situation occurs when the ventilation system fails. Gas levels may then rapidly build up to critical levels. In this case the major problem is replacement of oxygen by other gases, primarily CO2 produced from the pit as well as from the respiratory activity of the animals in the building. Lethal conditions could be reached in as few as 7 hours. Regarding the health of the pigs, ventilation failure in warm weather may allow temperature and humidity to increase to lethal levels in 3 hours. Ventilation systems should be monitored.

      A fourth potentially acute hazard arises from build-up of CH4, which is lighter than air and, when emitted from the manure pit, tends to accumulate in the upper portions of the building. There have been several instances of explosions occurring when the CH4 accumulation was ignited by a pilot light or a worker’s welding torch.

      Bioactive Aerosols of Particulates

      The sources of dust in confinement buildings are a combination of feed, dander and hair from the swine and dried faecal material (Donham and Scallon 1985). The particulates are about 24% protein and therefore have the potential not only for initiating an inflammatory response to foreign protein but also for initiating an adverse allergic reaction. The majority of particles are smaller than 5 microns, allowing them to be respired into the deep portions of the lungs, where they may produce a greater danger to health. The particulates are laden with microbes (104 to 107/m3 air). These microbes contribute several toxic/inflammatory substances including, among others, endotoxin (the most documented hazard), glucans, histamine and proteases. The recommended maximum concentrations for dusts are listed in table 2. Gases present within the building and bacteria in the atmosphere are adsorbed on the surface of the dust particles. Thus, the inhaled particles have the increased potentially hazardous effect of carrying irritating or toxic gases as well as potentially infectious bacteria into the lungs.

      Infectious Diseases

      Some 25 zoonotic diseases have been recognized as having occupational significance for agricultural workers. Many of these may be transmitted directly or indirectly from livestock. The crowded conditions prevailing in confinement systems offer a high potential for transmission of zoonotic diseases from livestock to humans. Swine confinement environment may offer a risk for transmission to workers of swine influenza, leptospirosis, Streptococcus suis and salmonella, for example. The poultry confinement environment may offer a risk for ornithosis, histoplasmosis, New Castle disease virus and salmonella. Bovine confinement could offer a risk for Q fever, Trichophyton verrucosum (animal ringworm) and leptospirosis.

      Biologicals and antibiotics have also been recognized as potential health hazards. Injectable vaccines and various biologicals are commonly used in veterinary preventive medical programmes in animal confinement. Accidental inoculation of Brucella vaccines and Escherichia coli bacteria has been observed to cause illness in humans.

      Antibiotics are commonly used both parenterally and incorporated in animal feed. Since it is recognized that feed is a common component of the dust present in animal confinement buildings, it is assumed that antibiotics are also present in the air. Thus, antibiotic hypersensitivity and antibiotic-resistant infections are potential hazards for the workers.


      Noise levels of 103 dBA have been measured within animal confinement buildings; this is above the TLV, and offers a potential for noise-induced hearing loss (Donham, Yeggy and Dauge 1988).

      Respiratory Symptoms of Livestock Confinement Workers

      The general respiratory hazards within livestock confinement buildings are similar regardless of the species of livestock. However, swine confinements are associated with adverse health effects in a larger percentage of workers (25 to 70% of active workers), with more severe symptoms than those in poultry or cattle confinements (Rylander et al. 1989). The waste in poultry facilities is usually handled in solid form, and in this instance ammonia seems to be the primary gaseous problem; hydrogen sulphide is not present.

      Subacute or chronic respiratory symptoms reported by confinement workers have been observed to be most frequently associated with swine confinement. Surveys of swine confinement workers have revealed that about 75% suffer from adverse acute upper respiratory symptoms. These symptoms can be broken down into three groups:

      1. acute or chronic inflammation of the respiratory airways (manifested as bronchitis)
      2. acquired occupational (non-allergic) constriction of the airways (asthma)
      3. delayed self-limited febrile illness with generalized symptoms (organic dust toxic syndrome (ODTS)).


      Symptoms suggestive of chronic inflammation of the upper respiratory system are common; they are seen in about 70% of swine confinement workers. Most commonly, they include tightness of the chest, coughing, wheezing and excess sputum production.

      In approximately 5% of workers, symptoms develop after working in the buildings for only a few weeks. The symptoms include chest tightness, wheezing and difficult breathing. Usually these workers are affected so severely that they are forced to seek employment elsewhere. Not enough is known to indicate whether this reaction is an allergic hypersensitivity or a non-allergic hypersensitivity to dust and gas. More typically, symptoms of bronchitis and asthma develop after 5 years of exposure.

      Approximately 30% of workers occasionally experience episodes of delayed symptoms. Approximately 4 to 6 hours after working in the building they develop a flu-like illness manifested by fever, headache, malaise, general muscle aches and chest pain. They usually recover from these symptoms in 24 to 72 hours. This syndrome has been recognized as ODTS.

      The potential for chronic lung damage certainly seems to be real for these workers. However, this has not been documented so far. It is recommended that certain procedures be followed to prevent chronic exposure as well as acute exposure to the hazardous materials in swine confinement buildings. Table 3 summarizes the medical conditions seen in swine confinement workers.

      Table 3. Respiratory diseases associated with swine production

      Upper airway disease

      Irritant rhinitis
      Allergic rhinitis

      Lower airway disease

      Occupational asthma
      Non-allergic asthma, hyperresponsive airways disease,
      or reactive airways disease syndrome (RADS)
      Allergic asthma (IgE mediated)
      Acute or subacute bronchitis
      Chronic bronchitis
      Chronic obstructive pulmonary disease (COPD)

      Interstitial disease

      Chronic interstitial infiltrate
      Pulmonary oedema

      Generalized illness

      Organic dust toxic syndrome (ODTS)

      Sources: Donham, Zavala and Merchant 1984; Dosman et al. 1988; Haglind and Rylander 1987; Harries and Cromwell 1982; Heedrick et al. 1991; Holness et al. 1987; Iverson et al. 1988; Jones et al. 1984; Leistikow et al. 1989; Lenhart 1984; Rylander and Essle 1990; Rylander, Peterson and Donham 1990; Turner and Nichols 1995.

      Worker Protection

      Acute exposure to hydrogen sulphide. Care should always be taken to avoid exposure to H2S that may be given off when agitating an anaerobic liquid manure storage tank. If the storage is under the building, it is best to stay out of the building when the emptying procedure is going on and for several hours afterwards, until air sampling indicates it is safe. Ventilation should be at the maximum level during this time. A liquid manure storage facility should never be entered without the safety measures mentioned above being followed.


      Particulate exposure. Simple management procedures, such as the use of automated feeding equipment designed to eliminate as much feed dust as possible should be used to control particulate exposure. Adding extra fat to feed, frequent power-washing of the building and installing slatted flooring that cleans well are all proven control measures. An oil-misting dust-control system is presently under study and may be available in the future. In addition to good engineering control, a good-quality dust mask should be worn.

      Noise. Ear protectors should be provided and worn, particularly when working in the building in order to vaccinate the animals or for other management procedures. A hearing conservation programme should be instituted.



      Monday, 28 March 2011 19:08

      Animal Husbandry

      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.


      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


      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







      Goats, other herbivores

      Handling hair, bone or other tissues



      Cattle, swine, goats, sheep

      Contact with placenta and other contaminated tissues



      Poultry, cattle

      Ingestion of contaminated food, water, milk



      Poultry, cattle, sheep, small mammals

      Ingestion of animal faeces



      Wild animals, swine, cattle, dogs

      Contaminated water on open skin



      Sheep, goats

      Direct contact with mucous membranes



      Parakeets, poultry, pigeons

      Inhaled desiccated droppings

      Q fever


      Cattle, goats, sheep

      Inhaled dust from contaminated tissues



      Wild carnivores, dogs, cats, livestock

      Exposure of virus-laden saliva to breaks in skin



      Poultry, swine, cattle

      Ingestion of food from contaminated organisms

      Tinea capitis


      Dogs, cats, cattle

      Direct contact



      Swine, dogs, cats, horses

      Eating poorly cooked flesh

      Tuberculosis, bovine


      Cattle, swine

      Ingestion of unpasteurized milk; inhalation of airborne droplets



      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 (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


      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.



      Monday, 28 March 2011 19:14

      Case Study: Animal Behaviours

      Understanding what influences animal behaviour can help make for a safer work environment. Genetics and learned responses (operant conditioning) influence the way an animal behaves. Certain breeds of bulls are generally more docile than others (genetic influence). An animal that has balked or refused to enter an area, and is successful at not doing so, will likely refuse to do so the next time. On repeated tries it will get more agitated and dangerous. Animals respond to the way in which they are treated, and draw upon past experiences when reacting to a situation. Animals that are chased, slapped, kicked, hit, yelled at, frightened and so on, will naturally have a sense of fear when a human is near. Thus, it is important to do everything possible to make movement of animals successful on the first attempt and as free of stress as possible for the animal.

      Domesticated animals living under fairly uniform conditions develop habits which are based on doing the same thing each day at a specific time. Confining bulls in a paddock and feeding them allows them to get used to humans and can be utilized with bull-confinement mating systems. Habits are also caused by regular changes in environmental conditions, such as temperature or humidity fluctuations when daylight turns to darkness. Animals are most active at the time of greatest change, which is at dawn or dusk, and least active either in the middle of the day or the middle of the night. This factor can be used to advantage in the movement or working of animals.

      Like animals in the wild, domesticated animals can protect territories. During feeding, this can appear as aggressive behaviour. Studies have shown that feed distributed in large, unpredictable patches eliminates territorial behaviour in livestock. When feed is distributed uniformly or in predictable patterns, it may result in fighting by animals to secure the feed and exclude others. Territorial protection may also occur when a bull is permitted to remain with the herd. The bull may view the herd and the range they cover as his territory, which means he will defend it against perceived and real threats, such as humans, dogs and other animals. Introducing a new or strange bull of breeding age into the herd almost always results in fighting to establish the dominant male.

      Bulls, due to having their eyes on the side of their head, have panoramic vision and very little depth perception. This means they can see about 270° around them, leaving a blind spot directly behind them and right in front of their noses (see figure 1). Sudden or unexpected movements from behind can “spook” the animal because it cannot determine the proximity or seriousness of the perceived threat. This can cause a “flight or fight” response in the animal. Because cattle have poor depth perception, they can also be easily frightened by shadows and movements outside of working or holding areas. Shadows falling within the working area may appear as a hole to the animal, which can cause it to balk. Cattle are colour blind, but do perceive colours as different shades of black and white.

      Many animals are sensitive to noise (compared with humans), especially at high frequencies. Loud, abrupt noises, such as metal gates clanging shut, head chutes latching and/or humans yelling can cause stress in the animals.

      Figure 1. Panoramic vision of cattle




      Monday, 28 March 2011 19:15

      Manure and Waste Handling

      The importance of the management of waste has increased as the intensity of agricultural production on farms has increased. Waste from livestock production is dominated by manure, but also includes bedding and litter, wasted feed and water and soil. Table 1 lists some relevant characteristics of manure; human waste is included both for comparison and because it too must be treated on a farm. The high organic content of manure provides an excellent growth medium for bacteria. The metabolic activity of bacteria will consume oxygen and maintain bulk-stored manure in an anaerobic state. Anaerobic metabolic activity can produce a number of well-known toxic gaseous by-products, including carbon dioxide, methane, hydrogen sulphide and ammonia.

      Table 1. Physical properties of manure as excreted per day per 1,000 lb of animal weight, excluding moisture.


      Weight (lb)

      Volume (ft3)

      Volatiles (lb)

      Moisture (%)


      As excreted

      As stored

      Dairy cow






      Beef cow






      Pig (grower)






      Sow (gestation)






      Sow and piglets






      Laying hens


















      Lamb (sheep)











      Source: USDA 1992.

      Management Processes

      The management of manure involves its collection, one or more transfer operations, storage or/and optional treatment and eventually utilization. The moisture content of manure as listed in table 1 determines its consistency. Wastes of different consistencies require different management techniques and therefore can present different health and safety hazards (USDA 1992). The reduced volume of solid or low-moisture manure generally permits lower equipment costs and energy requirements, but handling systems are not easily automated. The collection, transfer and any optional treatments of liquid waste are more easily automated and require less daily attention. Storage of manure becomes increasingly mandatory as the seasonal variability of the local crops increases; the storage method must be sized to meet the production rate and utilization schedule while preventing environmental damage, especially from water runoff. Options for utilization include use as plant nutrients, mulch, animal feed, bedding or a source to produce energy.

      Manure Production

      Dairy cows are typically raised on pastures, except when in holding areas for pre- and post-milking and during seasonal extremes. Water use for cleaning in milking operations can vary from 5 to 10 gallons per day per cow, where flushing of wastes is not practised, to 150 gallons per day per cow where it is. Therefore, the method used for cleaning has a strong influence on the method chosen for manure transport, storage and utilization. Because the management of beef cattle requires less water, beef manure is more often handled as a solid or semi-solid. Composting is a common storage and treatment method for such dry wastes. The local precipitation pattern also strongly influences the preferred waste management scheme. Excessively dry feedlots are apt to produce a downwind dust and odour problem.

      The major problems for swine raised on traditional pastures are the control of runoff and soil erosion due to the gregarious nature of pigs. One alternative is the construction of semi-enclosed pig buildings with paved lots, which also facilitates the separation of solid and liquid wastes; solids require some manual transfer operations but liquids can be handled by gravity flow. Waste-handling systems for fully enclosed production buildings are designed to collect and store waste automatically in a largely liquid form. Livestock playing with their watering facilities can increase the volumes of swine waste. Manure storage is generally in anaerobic pits or lagoons.

      Poultry facilities are generally divided into those for meat (turkeys and broilers) and egg (layers) production. The former are raised directly on prepared litter, which maintains the manure in a relatively dry state (25 to 35% moisture); the only transfer operation is mechanical removal, generally only once per year, and transport directly to the field. Layers are housed in stacked cages without litter; their manure can either be allowed to collect in deep stacks for infrequent mechanical removal or be automatically flushed or scraped in a liquid form much like swine manure.

      The consistency of waste from most other animals, like sheep, goats and horses, is largely solid; the major exception is veal calves, because of their liquid diet. Waste from horses contains a high fraction of bedding and may contain internal parasites, which limits its utilization on pasture land. Waste from small animals, rodents and birds may contain disease organisms that can be transmitted to humans. However, studies have shown that faecal bacteria do not survive on forage (Bell, Wilson and Dew 1976).

      Storage Hazards

      Storage facilities for solid wastes must still control water runoff and leaching into surface and ground water. Thus, they should be paved pads or pits (that may be seasonal ponds) or covered enclosures.

      Liquid and slurry storage is basically limited to ponds, lagoons, pits or tanks either below or above ground. Long-term storage is coincident with onsite treatment, usually by anaerobic digestion. Anaerobic digestion will reduce the volatile solids indicated in table 1, which also reduces odours emanating from eventual utilization. Unguarded below-surface holding facilities can lead to injuries or fatalities from accidental entry and falls (Knoblauch et al. 1996).

      The transfer of liquid manure presents a highly variable hazard from mercaptans produced by anaerobic digestion. Mercaptans (sulphur-containing gases) have been shown to be major contributors to the odour of manure and are all quite toxic (Banwart and Brenner 1975). Perhaps the most dangerous of the effects from H2S shown in table 2 is its insidious capacity to paralyze the sense of smell in the 50- to 100-ppm range, removing the sensory capacity to detect higher, rapidly toxic levels. Liquid storage for as short as 1 week is enough to initiate the anaerobic production of toxic mercaptans. Major differences in long-term manure gas generation rates are thought to be due to uncontrolled variations in the chemical and physical differences within the stored manure, such as temperature, pH, ammonia and organic loading (Donham, Yeggy and Dauge 1985).


      Table 2. Some important toxicologic benchmarks for hydrogen sulphide (H2S)

      Physiological or regulatory benchmark

      Parts per million (ppm)

      Odour detection threshold (rotten-egg smell)


      Offensive odour


      TLV-TWA = recommended exposure limit


      TLV-STEL = recommended 15-minute exposure limit


      Olfactory paralysis (cannot be smelled)


      Bronchitis (dry cough)


      IDLH (pneumonitis and pulmonary oedema)


      Rapid respiratory arrest (death in 1–3 breaths)


      TLV-TWA = Threshold limit values–Time weighted average; STEL = Short-term exposure level; IDLH = Immediately dangerous to life and health.

      The normally slow release of these gases during storage is greatly increased if the slurry is agitated to resuspend the sludge that accumulates at the bottom. H2S concentrations of 300 ppm have been reported (Panti and Clark 1991), and 1,500 ppm has been measured during the agitation of liquid manure. The rates of gas release during agitation are much too large to be controlled by ventilation. It is most important to realize that natural anaerobic digestion is uncontrolled and therefore highly variable. The frequency of serious and fatal over-exposures can be predicted statistically but not at any individual site or time. A survey of dairy farmers in Switzerland reported a frequency of about one manure gas accident per 1,000 person-years (Knoblauch et al. 1996). Safety precautions are necessary each time agitation is planned to avoid the unusually hazardous event. If the operator does not agitate, sludge will build up until it may have to be removed mechanically. Such sludge should be left to dry before someone physically enters an enclosed pit. There should be a written confined-space programme.

      Rarely used alternatives to anaerobic ponds include an aerobic pond, a facultative pond (one using bacteria that can grow under both aerobic and anaerobic conditions), drying (dewatering), composting or an anaerobic digester for biogas (USDA 1992). Aerobic conditions can be created either by keeping the liquid depth no more than 60 to 150 cm or by mechanical aeration. Natural aeration takes more space; mechanical aeration is more costly, as are the circulating pumps of a facultative pond. Composting may be conducted in windrows (rows of manure which must be turned every 2 to 10 days), a static but aerated pile or a specially constructed vessel. The high nitrogen content of manure must be reduced by mixing a high carbon amendment that will support the thermophilic microbial growth necessary for composting to control odours and remove pathogens. Composting is an economical method of treating small carcasses, if local ordinances permit. See also the article “Waste disposal operations” elsewhere in this Encyclopaedia. If a rendering or disposal plant is not available, other options include incineration or burial. Their prompt treatment is important to control herd or flock disease. Swine and poultry wastes are particularly amenable to methane production, but this utilization technique is not widely adopted.

      Thick crusts can form on top of liquid manure and appear solid. A worker may walk on this crust and break through and drown. Workers can also slip and fall into liquid manure and drown. It is important to keep rescue equipment near the liquid manure storage site and avoid working alone. Some manure gases, such as methane, are explosive, and “no smoking” signs should be posted in or around the manure storage building (Deere & Co. 1994).

      Application Hazards

      Transfer and utilization of dry manure can be by hand or with mechanical aids like a front-end loader, skid-steer loader and manure spreader, each of which presents a safety hazard. Manure is spread onto land as fertilizer. Manure spreaders are generally pulled behind a tractor and powered by a power-take-off (PTO) from the tractor. They are classified into one of four types: box-type with rear beaters, flail, V-tank with side discharge and closed tank. The first two are used to apply solid manure; the V-tank spreader is used to apply liquid, slurry or solid manure; and the closed tank spreader is used to apply liquid manure. The spreaders throw the manure over large areas either to the rear or sides. Hazards include the machinery, falling objects, dust and aerosols. Several safety procedures are listed in table 3.


      Table 3. Some safety procedures related to manure spreaders


      1. Only one person should operate the machine to avoid inadvertent activation by another person.

      2. Keep workers clear of active power-take offs (PTOs), beaters, augers and expellers.

      3. Maintain all guards and shields.

      4. Keep persons clear of rear and sides of the spreader, which can project heavy objects mixed into the manure as far as 30 m.

      5. Avoid dangerous unplugging operations by preventing spreader plugging:

      • Keep stones, boards and other objects out of the spreader.
      • In freezing weather, make sure flails and chains on flail-type spreaders are loose and unfrozen before operation.
      • Keep chains and beaters on beater-type spreaders in good operating order by replacing stretched chains and avoiding dropping loads of frozen manure onto the spreader chains.
      • Never get into an operating spreader to clean it.
      • Maintain the unloading auger and discharge expeller on V-tank spreaders so they operate freely.
      • In cold weather, clean the spreader insides so wet manure will not freeze the moving parts.


      6. Use good tractor and PTO safety practices.

      7. Make sure the relief valve on closed-tank spreaders is operative to avoid excessive pressures.

      8. When unhooking the spreader from the tractor, make sure the jack that holds the weight of the spreader tongue is secure and locked to prevent the spreader from falling.

      9. When the spreader is creating airborne dust or aerosols, use respiratory protection.

      Source: Deere & Co. 1994.





        1. Use proper ventilation in buildings and silos.
        2. Keep entrances to grain, feed and silage storage areas closed and locked.
        3. Post warning signs in feed and silage storage areas about the hazard of entrapment in flowing grain or feed.
        4. Maintain silo and bin ladders in good condition.
        5. Shield auger inlets to prevent contact with augers.
        6. Cover loading troughs on augers, elevators and conveyors with grating.
        7. Use caution when moving augers and elevators; check for overhead power lines.
        8. Assure that shields are in place for all feeding, grinding and other equipment.
        9. Be aware of health effects of breathing organic dust, and inform your doctor about recent dust exposure when seeking treatment for respiratory illness.
        10. Use automated or mechanized equipment to move decayed materials.
        11. Use source containment, local exhaust ventilation and wet methods to control organic dust.
        12. Use appropriate respiratory protection when dust exposure is unavoidable.



                        1. Establish good sanitation, vaccination and inoculation programmes.
                        2. When working with animals, plan an escape exit; have at least two ways out.
                        3. Livestock handlers should have enough strength and experience for the job.
                        4. Avoid working with animals when you are tired.
                        5. Use caution when approaching animals so as not to startle them.
                        6. Know the animals and be patient with them.
                        7. Dehorn dangerous animals.
                        8. Post warning signs where chemicals are stored; lock them in a room or cabinet.
                        9. Mix all chemicals outside or in a well-ventilated area.
                        10. Be careful when leading animals.
                        11. Wear rubber gloves when treating sick animals.
                        12. Vaccinate animals, and quarantine sick animals.
                        13. Wash hands after contact with calves with diarrhoea (scours).


                                        Containment and housing

                                          1. Make sure all pens, gates, loading chutes and fences are in good repair and strong enough to contain the animal.
                                          2. Do not allow tobacco smoking around farm buildings and fuel storage and refueling areas; post “no smoking” signs in these areas.
                                          3. Maintain fully charged ABC-type fire extinguishers in major farm buildings.
                                          4. Remove trash and debris around buildings to prevent fires and falls.
                                          5. Keep all buildings in good repair.
                                          6. Keep electrical wiring in good condition.
                                          7. Use adequate lighting in all buildings.
                                          8. Keep floors clean and free of broken concrete and slippery areas.


                                                        Waste disposal

                                                          1. Correctly dispose of all chemical containers following directions on the label.
                                                          2. Install vent pipes and exhaust fans in manure pits.



                                                            Monday, 28 March 2011 19:23


                                                            The dairy farmer is a livestock specialist whose aim is optimizing the health, nutrition and reproductive cycling of a herd of cows with the ultimate goal of maximal milk production. Major determinants of the farmer’s exposure to hazards are farm and herd size, labour pool, geography and degree of mechanization. A dairy farm may be a small family business milking 20 or fewer cows per day, or it may be a corporate operation using three shifts of workers to feed and milk thousands of cows around the clock. In regions of the world where the climate is quite mild, the cattle may be housed in open sheds with roofs and minimal walls. Alternatively, in some regions barns must be tightly closed to preserve sufficient heat to protect the animals and the watering and milking systems. All of these factors contribute variability to the risk profile of the dairy farmer. Nevertheless, there are a series of hazards which most people working in dairy farming around the world will encounter to at least some degree.

                                                            Hazards and Precautions


                                                            One potential hazard which clearly relates to the degree of mechanization is noise. In dairy farming, harmful noise levels are common and always related to some type of mechanical device. Leading offenders outside of the barn are tractors and chain-saws. Noise levels from these sources are often at or above the 90-100 dBA range. Within the barn, other noise sources include bedding choppers, small skid-steer loaders and milking pipeline vacuum pumps. Here again, sound pressures may exceed those levels generally considered to be damaging to the ear. Although the studies of noise-induced hearing loss in dairy farmers are limited in number, they combine to show a convincing pattern of hearing deficits affecting predominantly the higher frequencies. These losses can be quite substantial and occur considerably more frequently in farmers of all ages than in non-farm controls. In several of the studies, the losses were more notable in the left than the right ear—possibly because farmers spend much of their time with the left ear turned toward the engine and muffler when driving with an implement. Prevention of these losses may be accomplished by efforts directed at noise abatement and muffling, and institution of a hearing-conservation programme. Certainly, the habit of wearing hearing protective devices, either muffs or earplugs, may help substantially to reduce the next generation’s risk of noise-induced hearing loss.


                                                            The dairy farmer has contact with some chemicals which are commonly found in other types of agriculture, as well as some which are specific to the dairy industry, such as those used for cleaning the automated vacuum-powered milking pipeline system. This pipeline must be effectively cleaned before and after each use. Commonly this is done by first flushing the system with a very strong alkaline soap solution (typically 35% sodium hydroxide), followed by an acidic solution such as 22.5% phosphoric acid. A number of injuries have been observed in association with these chemicals. Spills have resulted in significant skin burns. Splatters may injure the cornea or conjunctivae of unprotected eyes. Tragic accidental ingestion—often by young children—which may occur when these materials are pumped into a cup and then briefly left unattended. These situations can be best prevented by the use of an automated, closed flush system. In the absence of an automated system, precautions must be taken to restrict access to these solutions. Measuring cups should be clearly labelled, reserved for only this purpose, never left unattended and rinsed thoroughly after each use.

                                                            Like others working with livestock, dairy farmers may have exposure to a variety of pharmaceutical agents ranging from antibiotics and progestational agents to prostaglandin inhibitors and hormones. Depending upon the country, dairy farmers also may use fertilizers, herbicides and insecticides with varying degrees of intensity. In general, the dairy farmer uses these agrochemicals less intensively than persons working in some other types of farming. However, the same care in mixing, applying and storing these materials is necessary. Appropriate application techniques and protective garb are as important for the dairy farmer as anyone else working with these compounds.

                                                            Ergonomic Risks

                                                            Although data on the prevalence of all musculoskeletal problems are currently incomplete, it is clear that dairy farmers have increased risk of arthritis of the hip and knee compared to nonfarmers. Similarly, their risk of back problems may also be elevated. Although not well studied, there is little question that ergonomics is a major problem. The farmer may routinely carry weights in excess of 40 kg—often in addition to considerable personal body weight. Tractor driving produces abundant vibration exposure. However, it is the portion of the job devoted to milking that seems most ergonomically significant. A farmer may bend or stoop 4 to 6 times in the milking of a single cow. These motions are repeated with each of a number of cows twice daily for decades. Carrying the milking equipment from stall to stall imposes an additional ergonomic load on the upper extremities. In countries where milking is less mechanized, the ergonomic load on the dairy farmer might be different, but still it is likely to reflect considerable repetitive strain. A potential solution in some countries is the shift to milking parlours. In this setting the farmer can milk a number of cows simultaneously while standing several feet below them in the central pit of the parlour. This eliminates the stooping and bending as well as the upper-extremity load of carrying equipment from stall to stall. The latter problem is also addressed by the overhead track systems being introduced in some Scandinavian countries. These support the weight of the milking equipment when moving between stalls, and can even provide a convenient seat for the milker. Even with these potential solutions, much remains to be learned about ergonomic problems and their resolution in dairy farming.


                                                            A closely linked problem is organic dust. This is a complex, often allergenic and generally ubiquitous material on dairy farms. The dust frequently has high concentrations of endotoxin and may contain beta-glucans, histamine and other biologically active materials (Olenchock et al. 1990). Levels of total and respirable dust may exceed 50 mg/m3 and 5 mg/m3, respectively, with certain operations. These most commonly involve work with microbially contaminated feed or bedding within a closed space such as a barn, hay loft, silo or grain bin. Exposure to these dust levels may result in acute problems such as ODTS or hypersensitivity pneumonitis (“farmer’s lung disease”). Chronic exposure may also play a role in asthma, farmer’s lung disease and chronic bronchitis, which seems to occur at twice the rate of a non-farm population (Rylander and Jacobs 1994). The prevalence rates of some of these problems are higher in settings where moisture levels in the feed are likely to be elevated and in areas where barns are more tightly closed because of climatic requirements. Various farming practices such as drying of the hay and shaking out of feed for the animals by hand, and the choice of bedding material, can be major determinants of the levels of both the dust and its associated illnesses. Farmers can often devise a number of techniques to minimize either the amount of microbial overgrowth or its subsequent aerosolization. Examples include the use of sawdust, newspapers and other alternative materials for bedding instead of moulded hay. If hay is used, the addition of a quart of water to the cut surface of the bale minimizes the dust generated by a mechanical bedding chopper. Capping vertical silos with plastic sheets or tarpaulins without additional feed on top of this layer minimizes the dust of subsequent uncapping. The use of small amounts of moisture and/or ventilation in situations where dust is likely to be generated is often possible. Finally, farmers must anticipate potential dust exposures and use appropriate respiratory protection in these situations.


                                                            Allergens may represent a troublesome health challenge for some dairy farmers. Major allergens appear to be those encountered in the barns, typically animal danders and “storage mites” living in feed stored within the barns. One study has extended the storage mite problem beyond the barn, finding sizeable populations of these species living within farmhouses as well (van Hage-Hamsten, Johansson and Hogland 1985). Mite allergy has been confirmed as a problem in a number of parts of the world, often with differing species of mites. Reactivity to these mites, to cow dander and to multiple other less significant allergens, results in several allergic manifestations (Marx et al. 1993). These include immediate onset of nasal and eye irritation, allergic dermatitis and, of greatest concern, allergy-mediated occupational asthma. This can occur as either an immediate or delayed (up to 12 hours) reaction and may occur in individuals not previously known to be asthmatic. It is of concern because the dairy farmer’s involvement in barn activities is daily, intensive and lifelong. With this nearly continual allergic re-challenge, progressively more severe asthma is likely to be seen in some farmers. Prevention includes avoidance of dust, which is the most effective and, unfortunately, the most difficult intervention for most dairy farmers. The results of medical therapies, including allergy shots, topical steroids or other anti-inflammatory agents, and symptomatic relief with bronchodilators, have been mixed.



                                                            Monday, 28 March 2011 19:24

                                                            Cattle, sheep and goats

                                                            Material on hair-cutting and shearing was written with the assistance of J.F. Copplestone’s article on the subject in the 3rd edition of this Encyclopaedia.

                                                            Several animals convert high-fibre feeds, called roughage (over 18% fibre), into edible food that is consumed by humans. This ability comes from their four-stomach digestion system, which includes their largest stomach, the rumen (for which they gain the designation ruminants) (Gillespie 1997). Table 1 shows the various types of ruminant livestock that have been domesticated and their uses.

                                                            Table 1. Types of ruminants domesticated as livestock

                                                            Ruminant type



                                                            Meat, milk, draught


                                                            Meat, wool


                                                            Meat, milk, mohair

                                                            Camelids (llama, alpaca, dromedary and bactrian camels)

                                                            Meat, milk, hair, draught

                                                            Buffalo (water buffalo)

                                                            Meat, draught




                                                            Meat, milk, wool


                                                            Meat, milk, draught


                                                            Production Processes

                                                            Processes for rearing ruminants vary from intensive, high-production operations such as raising beef cattle on large, 2,000-km2 ranches in Texas to communal grazing such as the nomadic herders of Kenya and the United Republic of Tanzania. Some farmers use their cattle as oxen for traction power in farm tasks such as ploughing. In humid areas, water buffalo serve the same purpose (Ker 1995). The trend is toward high-production, intensive systems (Gillespie 1997).

                                                            High-volume, intensive beef production depends on various interdependent operations. One is the cow-calf system, which involves keeping a herd of cows. The cows are bred by bulls or artificial insemination annually to produce calves, and, after weaning, the calves are sold to cattle feeders to raise for slaughter. Male calves are castrated for the slaughter market; a castrated calf is called a steer. Pure-bred breeders maintain the herds of breeding stock, including bulls, which are very dangerous animals.

                                                            Sheep are produced in either range or farm flocks. In range production, flocks of 1,000 to 1,500 ewes are common. In farm flocks, production is usually small and typically a secondary enterprise. Sheep are raised for their wool or as feeder lambs for the slaughter market. Lambs are docked, and most male lambs are castrated. Some enterprises specialize in raising rams for pure-bred breeding.

                                                            Goats are raised through either range or small-farm production for their mohair, milk and meat. Pure-bred breeders are small operations that raise rams for breeding does. Specific breeds exist for each of these products. The goats are dehorned, and most males are castrated. Goats browse on shoots, twigs and leaves of brush plants, and thus they may also be used to control brush on a ranch or farm.

                                                            Other major processes involved in rearing cattle, sheep and goats include feeding, disease and parasite control, hair clipping and fleece shearing. The milking process and livestock waste disposal are addressed in other articles in this chapter.

                                                            Cattle, sheep and goats are fed in several ways, including grazing or feeding hay and silage. Grazing is the least expensive way to deliver forage to animals. Animals typically graze on pastures, wild lands or crop residues, such as corn stalks, which remain in the field after crop harvests. Hay is harvested from the field and typically stored loose or in stacked bales. The feeding operation includes moving the hay from the stack to the open field or into mangers to feed the animals. Some crops such as corn are harvested and converted into silage. Silage is typically moved mechanically into mangers for feeding.

                                                            The control of diseases and parasites in cattle, sheep and goats is an integral part of the livestock-rearing process and requires animal contact. Routine visits to the herd by a veterinarian are an important part of this process, as is observing vital signs. Timely vaccination against diseases and quarantining diseased animals are also important.

                                                            External parasites include flies, lice, mange, mites and ticks. Chemicals are one control against these parasites. Pesticides are applied by spraying or through insecticide-impregnated ear tags. The heel fly lays eggs on the hair of cattle, and its larva, the cattle grub, burrows into the skin. A control for this grub is systemic pesticides (spread throughout the body through spray, dips or as a feed additive). Internal parasites, including roundworms or flatworms, are controlled with drugs, antibiotics or drenches (oral administration of a liquid medication). Sanitation is also a strategy for the control of infectious diseases and parasite infestations (Gillespie 1997).

                                                            The removal of hair from live animals helps to maintain their cleanliness or comfort and to prepare them for exhibitions. Hair may be sheared from live animals as a product, such as the fleece from sheep or mohair from goats. The sheep shearer catches the animal in a pen and drags it to a stand where it is laid on its back for the shearing operation. It is pinned by the shearer’s legs. Hair cutters and sheep shearers use a hand-operated scissors or motorized shears to clip the hair. The motorized shears are typically powered by electricity. Prior to shearing and also as part of gestation management, sheep are tagged and crutched (i.e., hair encrusted with faeces is removed). The cut fleece is manually trimmed according to the quality and staple of the hair. It is then compressed into packs for transportation using a hand-operated screw or hydraulic ram.

                                                            Facilities used for raising cattle, sheep and goats are generally considered to be either confined or unconfined. Confined facilities include confinement houses, feedlots, barns, corrals (holding, sorting and crowding pens), fences and working and loading chutes. Unconfined facilities refer to pasture or range operations. Feeding facilities include storage facilities (vertical and horizontal silos), feed grinding and mixing equipment, haystacks, conveying equipment (including augers and elevators), feed bunks, water fountains and mineral and salt feeders. In addition, sun protection may be provided by sheds, trees or overhead lattice work. Other facilities include back rubbers for parasite control, creep-feeders (allows feeder calves or lambs to feed without adults feeding), self-feeders, calf shelters, cattle-guard gates and cattle treatment stalls. Fencing may be used around pastures, and these include barbed wire and electric fences. Woven wire may be required to contain goats. Free-ranging animals would require herding to control their movement; goats may be tethered, but require shade. Dipping tanks are used for parasite control in large sheep flocks (Gillespie 1997).


                                                            Table 2 shows several other processes of cattle, sheep and goat handling, with associated hazardous exposures. In a survey of farm workers in the United States (Meyers 1997), handling livestock represented 26% of lost-time injuries. This percentage was higher than any other farm activity, as shown in figure 1. These figures would be expected to be representative of the injury rate in other industrialized countries. In countries where draught animals are common, injury rates would be expected to be higher. Injuries from cattle usually occur in farm buildings or in the vicinity of buildings. Cattle inflict injuries when they kick or step on people or crush them against a hard surface such as the side of a pen. People may also be injured by falling when working with cattle, sheep and goats. Bulls inflict the most serious injuries. Most of the people injured are family members rather than hired workers. Fatigue can reduce judgement, and thus increase the chance of injury (Fretz 1989).

                                                            Table 2. Livestock rearing processes and potential hazards


                                                            Potential hazardous exposures

                                                            Breeding, artificial inseminating

                                                            Violent acts by bulls, rams or bucks; slips and falls;
                                                            zoonoses; organic dust and dander


                                                            Organic dust; silo gas; machines; lifting; electricity

                                                            Calving, lambing, kidding

                                                            Lifting and pulling; animal behaviour

                                                            Castrating, docking

                                                            Animal behaviour; lifting; cuts from knives


                                                            Animal behaviour; cuts from trimmers; caustic
                                                            salves; burns from electric irons

                                                            Branding and marking

                                                            Burns; animal behaviour


                                                            Animal behaviour; needle sticks

                                                            Spraying and dusting/drenching, worming


                                                            Foot/hoof trimming

                                                            Animal behaviour; awkward postures; tool-related
                                                            cuts and pinches

                                                            Shearing, tagging and crutching, washing and clipping

                                                            Awkward postures and lifting; animal behaviour;
                                                            hand-shearer cuts; electricity

                                                            Loading and unloading

                                                            Animal behaviour

                                                            Manure handling

                                                            Manure gases; slips and falls; lifting; machines

                                                            Sources: Deere & Co. 1994; Fretz 1989; Gillespie 1997; NIOSH 1994.


                                                             Figure 1. Estimates of lost-time injury frequency by farm activity in the United States, 1993


                                                            Livestock exhibit behaviours that can lead to injuries of workers. The herding instinct is strong among animals such as cattle or sheep, and imposed limits such as isolation or overcrowding can lead to unusual behavioural patterns. Reflexive response is a common defensive behaviour among animals, and it can be predicted. Territorialism is another behaviour that is predictable. A reflexive escape struggle is apparent when an animal is removed from its normal quarters and placed in a confined environment. Animals that are restrained by chutes for loading for transportation will exhibit agitated reflex response behaviour.

                                                            Dangerous environments are numerous in cattle, sheep and goat production facilities. These include slippery floors, manure pits, corrals, dusty feed areas, silos, mechanized feeding equipment and animal confinement buildings. Confinement buildings may have manure storage pits, which can emit lethal gases (Gillespie 1997).


                                                            Heat exhaustion and stroke are potential hazards. Heavy physical labour, stress and strain, heat, high humidity and dehydration from lack of drinking water all contribute to these hazards.

                                                            Livestock handlers are at risk for developing respiratory illness from exposure to inhaled dusts. A common illness is organic dust toxic syndrome. This syndrome may follow exposures to heavy concentrations of organic dusts contaminated with micro-organisms. About 30 to 40% of workers who are exposed to organic dusts will develop this syndrome, which includes the conditions shown in table 3; this table also shows other respiratory conditions (NIOSH 1994).

                                                            Table 3. Respiratory illnesses from exposures on livestock farms

                                                            Organic dust toxic syndrome conditions

                                                            Precipitin-negative farmer’s lung disease

                                                            Pulmonary mycotoxicosis

                                                            Silo unloader’s syndrome

                                                            Grain fever in grain elevator workers

                                                            Other important respiratory illnesses

                                                            “Silo fillers’ disease” (acute toxic inflammation of the lung)

                                                            “Farmer’s lung disease” (hypersensitivity pneumonitis)


                                                            Asphyxiation (suffocation)

                                                            Toxic gas inhalation (for example, manure pits)


                                                            Hair cutters and sheep shearers face several hazards. Cuts and abrasions may result during the shearing operation. Animal hoofs and horns also present potential hazards. Slips and falls are an ever-present hazard while handling the animals. Power for the shears is sometimes transferred by belts, and guards must be maintained. Electrical hazards are also present. Shearers also face postural hazards, particularly to the back, as a result of catching and tipping the sheep. Constraining the animal between the shearer’s legs tends to strain the back, and torsional movements are common while shearing. Manual shearing usually results in tenosynovitis.

                                                            The control of insects on cattle, sheep and goats with pesticide spray or powder can expose workers to the pesticide. Sheep dips submerge the animal in a pesticide bath, and handling the animal or contact with the bath solution or contaminated wool can also expose workers to the pesticide (Gillespie 1997).

                                                            Common zoonoses include rabies, brucellosis, bovine tuberculosis, trichinosis, salmonella, leptospirosis, ringworm, tapeworm, orf virus disease, Q fever and spotted fever. Diseases that may be contracted while working with hair and fleece include tetanus, salmonellosis from tagging and crutching, leptospirosis, anthrax and parasitic diseases.

                                                            Animal faeces and urine also provide a mechanism for infection of workers. Cattle are a reservoir for cryptosporidosis, a disease that can be transmitted from cattle to humans through the faecal-oral route. Calves with diarrhoea (scours) may harbour this disease. Schistosomiasis, an infection by blood flukes, is found in cattle, water buffalo and other animals in several parts of the world; its life cycle goes from eggs excreted in urine and faeces, developing into larvae, which enter snails, then to free-swimming cercariae that attach to and penetrate human skin. Penetration can occur while workers are wading in water.

                                                            Some zoonoses are arthropod-borne viral diseases. The primary vectors for these diseases are mosquitoes, ticks and sandflies. These diseases include arboviral encephalitides transmitted by ticks and milk from sheep, babesiosis transmitted by ticks from cattle and Crimean-Congo haemorrhagic fever (Central Asian haemorrhagic fever) transmitted by mosquitoes and ticks from cattle, sheep and goats (as amplifying hosts) during epizootics (Benenson 1990; Mullan and Murthy 1991).

                                                            Preventive Action

                                                            The principal occupational hazards that occur in rearing ruminants include injuries, respiratory problems and zoonotic diseases. (See “A checklist for livestock rearing safety practices”.)

                                                            Stair steps should be maintained in good condition, and floors must be even to reduce fall hazards. Guards on belts, mechanical screws, compression rams and shear sharpening equipment should be maintained. Wiring should be maintained in good condition to prevent electrical shock. Ventilation should be assured wherever internal combustion engines are used in barns.

                                                            Training and experience in properly handling animals helps to prevent injuries related to the animals’ behaviour. Safe livestock handling requires understanding of both innate and acquired components of animal behaviour. Facilities should be designed so workers do not have to enter small or enclosed areas with animals. Lighting should be diffuse, since animals may become confused and balk around bright lights. Sudden noises or movements may startle cattle, causing them to crowd a person against hard surfaces. Even clothing hanging on fences flapping in the wind can startle cattle. They should be approached from the front so as not to surprise them. Avoid use of contrasting patterns in cattle facilities, because cattle will slow or stop when they see these patterns. Shadows across the floor should be avoided because cattle may refuse to cross over them (Gillespie 1997).

                                                            Risks of organic dust exposure can be minimized in several ways. Workers should be aware of the health effects of breathing organic dust and inform their physician about recent dust exposures when seeking help for respiratory illness. Minimizing spoilage of feed can minimize potential fungal spore exposures. To avoid such hazards, workers should use mechanized equipment to move decaying materials. Farm operators should use local exhaust ventilation and wet methods of dust suppression to minimize exposure. Appropriate respirators should be worn when organic dust exposure cannot be avoided (NIOSH 1994).

                                                            Preventing zoonoses depends upon maintaining clean livestock facilities, vaccinating the animals, quarantine of sick animals and avoiding exposure to sick animals. Rubber gloves should be worn when treating sick animals to avoid exposures through any cuts in the hands. Workers who become sick after contact with a sick animal should seek medical help (Gillespie 1997).



                                                            Monday, 28 March 2011 19:29


                                                            Pigs were primarily domesticated from two wild stocks—the European wild boar and the East Indian pig. The Chinese domesticated the pig as early as 4900 BC, and today more than 400 million pigs are reared in China out of 840 million worldwide (Caras 1996).

                                                            Pigs are reared primarily for food and have many distinguishing attributes. They grow fast and large, and the sows have large litters and short gestation periods of about 100 to 110 days. Pigs are omnivores and eat berries, carrion, insects and garbage, as well as the corn, silage and pasture of high-production enterprises. They convert 35% of their feed into meat and lard, which is more efficient than ruminant species such as cattle (Gillespie 1997).

                                                            Production Processes

                                                            Some pig holdings are small—for example, one or two animals, which can represent much of a family’s wealth (Scherf 1995). Large pig operations include two major processes (Gillespie 1997).

                                                            One process is pure-bred production, in which pig breeding stock are improved. Within the pure-bred operation, artificial insemination is prevalent. Pure-bred boars are typically used to breed sows in the other major process, commercial production. The commercial production process rears pigs for the slaughter market and typically follows one of two different types of operations. One operation is a two-stage system. The first stage is feeder pig production, which uses a herd of sows to farrow litters of 14 to 16 piglets per sow. The pigs are weaned, then sold to the next stage of the system, the buying and finishing enterprise, which feeds them for the slaughter market. The most common feeds are corn and soybean oil meal. The feed grains are typically ground.

                                                            The other and most common operation is the complete sow and litter system. This production operation rears a herd of breeding sows and farrowing pigs, caring for and feeding the farrowed pigs for the slaughter market.

                                                            Some sows give birth to a litter that may outnumber her teats. To feed the excess piglets, a practice is to spread piglets from large litters into other sows’ smaller litters. Pigs are born with needle teeth, which are typically clipped at the gum-line before the pig is two days old. Ears are notched for identification. Tail docking occurs when the pig is about 3 days old. Male pigs raised for the slaughter market are castrated before they are 3 weeks old.

                                                            Maintaining a healthy herd is the single most important management practice in pig production. Sanitation and the selection of healthy breeding stock are important. Vaccination, sulpha drugs and antibiotics are used to prevent many infectious diseases. Insecticides are used to control lice and mites. The large roundworm and other parasites of pigs are controlled through sanitation and drugs.

                                                            Facilities used for pig production include pasture systems, a combination of pasture and low-investment housing and high-investment total-confinement systems. The trend is toward more confinement housing because it produces faster growth than does pasture rearing. However, pasture is valuable in feeding the pig-breeding herd to prevent fattening the breeding herd; it may be used for all or part of the production operation with the use of portable housing and equipment.

                                                            Confinement buildings require ventilation to control temperature and moisture. Heat may be added in farrowing houses. Slotted floors are used in confinement houses as a labour-saving approach for handling manure. Fencing and handling feeding and watering equipment are needed for the pig production enterprise. Facilities are cleaned by power washing and disinfecting after all bedding, manure and feed are removed (Gillespie 1997).


                                                            Injuries from pigs usually occur within or close to farm buildings. Dangerous environments include slippery floors, manure pits, automatic feeding equipment and confinement buildings. Confinement buildings have a manure storage pit that emits gases that, if not ventilated, can kill not only pigs, but workers as well.

                                                            Pig behaviour can pose hazards to workers. A sow will attack if her piglets are threatened. Pigs can bite, step on or knock people down. They tend to stay in or return to familiar areas. A pig will try to return to the herd when attempts are made to separate it. Pigs are likely to balk when moved from a dark area into a light area, such as out of a pig house into the daylight. At night, they will resist moving into dark areas (Gillespie 1997).

                                                            In a Canadian study of pig farmers, 71% reported chronic back problems. Risk factors include intervertebral disc loading associated with driving and sitting for long periods while operating heavy equipment. This study also identified lifting, bending, twisting, pushing and pulling as risk factors. In addition, more than 35% of these farmers reported chronic knee problems (Holness and Nethercott 1994).

                                                            Three types of air exposures pose hazards on pig farms:

                                                            1. dust from feed, animal hair and faecal matter
                                                            2. pesticides used on pigs and other chemicals, such as disinfectants
                                                            3. ammonia, hydrogen sulphide, methane and carbon monoxide from manure storage pits.


                                                            Fires in buildings are another potential hazard, as is electricity.

                                                            Some zoonotic infections and parasites can be transmitted from the pig to the worker. Common zoonoses associated with pigs include brucellosis and leptospirosis (swineherd’s disease).

                                                            Preventive Action

                                                            Several safety recommendations have evolved for the safe handling of pigs (Gillespie 1997):

                                                            • Working with small pigs in the same pen as the sow should be avoided.
                                                            • A hurdle or solid panel should be used when handling pigs to avoid bites and being knocked over.
                                                            • A pig can be moved backwards by placing a basket over its head.
                                                            • Children should be kept out of pig pens and not allowed to reach through fences to pet pigs.
                                                            • Because of their herding instincts, it is easier to separate a group of pigs from a herd than a single animal.
                                                            • Pigs can be moved from dark to light areas with the use of artificial light. When pigs are moved at night, such as through chutes or alleys, a light should be placed at the destination.
                                                            • Loading chutes should be level or at not more than a 25-degree angle.


                                                            Musculoskeletal injury risk can be decreased by reducing exposure to repetitive trauma (by taking frequent breaks or by varying the kinds of tasks), improving posture, reducing the weight lifted (use co-worker or mechanical assistance) and avoiding rapid, jerking movements.

                                                            Dust control techniques include lowering stock density to reduce dust concentration. In addition, automatic feed delivery systems should be enclosed to contain dust. Water misting can be used, but it is ineffective in freezing weather and can contribute to the survival of bioaerosols and increase endotoxin levels. Filters and scrubbers in the air handling system show promise in cleaning dust particles from recirculated air. Respirators are another way to control dust exposures (Feddes and Barber 1994).

                                                            Vent pipes should be installed in manure pits to prevent dangerous gases from recirculating into the farm buildings. Electrical power should be maintained to vent fans at the pits. Workers should be trained in the safe use of pesticides and other chemicals, such as disinfectants, used in pig production.

                                                            Cleanliness, vaccination, quarantine of sick animals and avoiding exposures are ways to control zoonoses. When treating sick pigs, wear rubber gloves. A person who becomes sick after working with sick pigs should contact a physician (Gillespie 1997).



                                                            Page 8 of 9

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                                                            Part I. The Body
                                                            Cardiovascular System
                                                            Physical, Chemical, and Biological Hazards
                                                            Digestive System
                                                            Mental Health
                                                            Mood and Affect
                                                            Musculoskeletal System
                                                            Nervous System
                                                            Renal-Urinary System
                                                            Reproductive System
                                                            Respiratory System
                                                            Sensory Systems
                                                            Skin Diseases
                                                            Systematic Conditions
                                                            Part II. Health Care
                                                            First Aid & Emergency Medical Services
                                                            Health Protection & Promotion
                                                            Occupational Health Services
                                                            Part III. Management & Policy
                                                            Disability and Work
                                                            Education and Training
                                                            Case Studies
                                                            Ethical Issues
                                                            Development, Technology, and Trade
                                                            Labour Relations and Human Resource Management
                                                            Resources: Information and OSH
                                                            Resources, Institutional, Structural and Legal
                                                            Community level
                                                            Regional and National Examples
                                                            International, Government and Non-Governmental Safety and Health
                                                            Work and Workers
                                                            Worker's Compensation Systems
                                                            Topics In Workers Compensation Systems
                                                            Part IV. Tools and Approaches
                                                            Biological Monitoring
                                                            Epidemiology and Statistics
                                                            Goals, Principles and Methods
                                                            Physical and Physiological Aspects
                                                            Organizational Aspects of Work
                                                            Work Systems Design
                                                            Designing for Everyone
                                                            Diversity and Importance of Ergonomics
                                                            Occupational Hygiene
                                                            Personal Protection
                                                            Record Systems and Surveillance
                                                            General Principles of Toxicology
                                                            Mechanisms of Toxicity
                                                            Toxicology Test Methods
                                                            Regulatory Toxicology
                                                            Part V. Psychosocial and Organizational Factors
                                                            Psychosocial and Organizational Factors
                                                            Theories of Job Stress
                                                            Chronic Health Effects
                                                            Stress Reactions
                                                            Individual Factors
                                                            Career Development
                                                            Macro-Organizational Factors
                                                            Job Security
                                                            Interpersonal Factors
                                                            Factors Intrinsic to the Job
                                                            Organizations and Health and Safety
                                                            Part VI. General Hazards
                                                            Barometric Pressure Increased
                                                            Barometric Pressure Reduced
                                                            Biological Hazards
                                                            Disasters, Natural and Technological
                                                            Heat and Cold
                                                            Hours of Work
                                                            Indoor Air Quality
                                                            Indoor Environmental Control
                                                            Radiation: Ionizing
                                                            Radiation: Non-Ionizing
                                                            Visual Display Units
                                                            Part VII. The Environment
                                                            Environmental Health Hazards
                                                            Environmental Policy
                                                            Environmental Pollution Control
                                                            Part VIII. Accidents and Safety Management
                                                            Accident Prevention
                                                            Audits, Inspections and Investigations
                                                            Safety Applications
                                                            Safety Policy and Leadership
                                                            Safety Programs
                                                            Part IX. Chemicals
                                                            Using, Storing and Transporting Chemicals
                                                            Minerals and Agricultural Chemicals
                                                            Metals: Chemical Properties and Toxicity
                                                            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
                                                            Overview and Health Effects
                                                            Food Processing Sectors
                                                            Livestock Rearing
                                                            Paper and Pulp Industry
                                                            Major Sectors and Processes
                                                            Disease and Injury Patterns
                                                            Part XI. Industries Based on Natural Resources
                                                            Iron and Steel
                                                            Mining and Quarrying
                                                            Oil Exploration and Distribution
                                                            Power Generation and Distribution
                                                            Part XII. Chemical Industries
                                                            Chemical Processing
                                                            Examples of Chemical Processing Operations
                                                            Oil and Natural Gas
                                                            Pharmaceutical Industry
                                                            Rubber Industry
                                                            Part XIII. Manufacturing Industries
                                                            Electrical Appliances and Equipment
                                                            Metal Processing and Metal Working Industry
                                                            Smelting and Refining Operations
                                                            Metal Processing and Metal Working
                                                            Microelectronics and Semiconductors
                                                            Glass, Pottery and Related Materials
                                                            Printing, Photography and Reproduction Industry
                                                            Part XIV. Textile and Apparel Industries
                                                            Clothing and Finished Textile Products
                                                            Leather, Fur and Footwear
                                                            Textile Goods Industry
                                                            Part XV. Transport Industries
                                                            Aerospace Manufacture and Maintenance
                                                            Motor Vehicles and Heavy Equipment
                                                            Ship and Boat Building and Repair
                                                            Part XVI. Construction
                                                            Health, Prevention and Management
                                                            Major Sectors and Their Hazards
                                                            Tools, Equipment and Materials
                                                            Part XVII. Services and Trade
                                                            Education and Training Services
                                                            Emergency and Security Services
                                                            Emergency and Security Services Resources
                                                            Entertainment and the Arts
                                                            Arts and Crafts
                                                            Performing and Media Arts
                                                            Entertainment and the Arts Resources
                                                            Health Care Facilities and Services
                                                            Ergonomics and Health Care
                                                            The Physical Environment and Health Care
                                                            Healthcare Workers and Infectious Diseases
                                                            Chemicals in the Health Care Environment
                                                            The Hospital Environment
                                                            Health Care Facilities and Services Resources
                                                            Hotels and Restaurants
                                                            Office and Retail Trades
                                                            Personal and Community Services
                                                            Public and Government Services
                                                            Transport Industry and Warehousing
                                                            Air Transport
                                                            Road Transport
                                                            Rail Transport
                                                            Water Transport
                                                            Part XVIII. Guides
                                                            Guide to Occupations
                                                            Guide to Chemicals
                                                            Guide to Units and Abbreviations