Ricky Langley
Duke University
Durham, NC 27710


Farmers raising swine are exposed to numerous hazards daily. Fortunately, fatal injuries are rare and serious injuries can be prevented using appropriate protective equipment. Providing a safe workplace not only prevents illness and injury in the farmer but the animals will also benefit (reduced mortalities) and the farmer will probably notice economic benefit as well. This paper will discuss several health and safety topics involving working on swine farms: needlestick injuries, zoonotic infections, back injuries and repetitive motion disorders, weather-related injuries, respiratory problems, hearing loss, and electrical and mechanical injuries.

Needlestick Injuries

Needles are used to vaccinate, give medications, and draw blood from swine. Needles may cause puncture injuries or lacerations if the needle slips as the animal is moving or when the farmer is recapping a used needle. Occasionally, the farmer's wound may be contaminated with animal waste and subsequent infection may occur. Additionally, an individual may have an allergy to a medication used to treat the animal. For example, if an individual has a penicillin allergy and, while treating a hog with antibiotic containing penicillin the farmer accidently inoculates himself, he may suffer severe allergic reaction to the penicillin.

Another risk is the use of prostaglandins in individuals with asthma or pregnant farm workers. Accidental ingestion may trigger an asthma attack or induce labor in the pregnant worker. There is a theoretical risk of developing an infection from injecting a modified live viral or bacterial product. This risk is heightened in individuals with an immunocompromising condition, such as AIDS.

Zoonotic Infections

A zoonotic infection is one that can be transmitted between animals and man. Several swine infections can be transmitted to humans, some with potentially serious outcomes. Included among the diseases which may occur from exposure to zoonotic agents in swine are: brucellosis, erysipeloid, streptococcus suis meningitis, ascariasis, swine influenza, scabies, ringworm, leptospirosis, toxoplasmosis, salmonellosis, trichinosis, and cysticercosis.

In a study of swine veterinarians, 13% reported a zoonotic infection during their career. Additionally, in meat-packing facilities, outbreaks of brucellosis have been reported. Toxoplasmosis is a risk for the fetus of pregnant workers, and streptococcus suis meningitis may be fatal and permanent hearing loss has been reported in survivors.

Fortunately, many zoonotic infections can be prevented by using good personal hygiene methods, i.e., primarily good hand washing. Additionally, certain infections, such as cysticercosis and trichinosis are primarily due to the ingestion of improperly cooked meat and pose less of an occupational risk to swine handlers. All workers should insure that they have had a tetanus immunization within the last ten years.

If possible, all animals that are sick should be isolated from healthy animals and special attention paid while handling these animals. Any injury that occurs should be immediately cleaned with soap and water. If signs of infection develop such as pus, redness around the site, swelling or fever occur, then medical attention should be sought. Any prolonged unexplained illness should also be evaluated by a physician.


Farmers are exposed to loud noises from both animals and equipment on the farm. Studies have even detected noise induced hearing damage in teenagers that work on farms.

On swine farms, noise levels may easily exceed 95 decibels during feeding time and bleeding of hogs. Nose levels up to 110-115 decibels have been recorded. The OSHA limit in general industry for noise exposure is to 90 decibels over an eight hour work shift.

Excessive exposure to noise, beside causing hearing loss, can also result in psychological and possibly physiologic damage to the body. The use of ear plugs are highly recommended. A periodic audiogram can be used to determine if there is evidence of hearing loss and whether it is stable or progressive. Loud equipment should be inspected and parts well lubricated. Other ways of reducing noise levels include improving handling procedures and facility design and using low-noise fans. Although expensive an automatic or mechanically assisted feeding system can be installed to feed all hogs at once. This reduces noise from hogs waiting to be fed and reduces the amount of time it takes to feed them.

Electrical and Mechanical Injuries

Many injuries occur on a farm due to running into or being hit by equipment. Occasionally head injuries occur from hitting overhead equipment when the farmer is moving around or stands up. Fans that are not properly shielded may result in serious cuts if accidentally touched. Another frequently reported injury among swine practitioners was due to the use of hog snares. Presumably, head injuries occur as result of the snare slipping out of the helper's hand and hitting the practitioner who is kneeling or bending over the snared hog. Unguarded chains, sprockets and pulleys may act as pinch points. Lacerations, avulsion injuries, or crushing injuries may occur.

Electrical shocks may occur from damaged cords or light sockets. Improper grounding, stray voltage and faulty wiring in addition to wet surfaces and metal pins which serve as good electrical conductors place the worker at risk for electrocution. Additionally, damage to electrical wires is also a fire hazard. All equipment should be properly guarded and routinely maintained. Guards should always be replaced after removal for equipment repair. Fans should be screened to comply with pertinent regulations.

Weather Extremes

Working in extreme temperatures may present many hazards to the swine worker. Very cold conditions aggravate pre-existing health problems, such as Raynaud's disease, asthma, and diabetes. Frostbite and hypothermia may occur. Snow and ice on walkways also increase the risk of falls. At high temperatures, physical exertion may lead to heat exhaustion, dehydration, heat cramps, heat rashes, and heat strokes.

Workers should properly dress for the weather, preferably in layered clothing. Regular breaks and adequate amounts of water should be readily available. Workers should be encouraged to drink water to prevent dehydration during the summer. The use of cap and gloves will help to prevent heat loss during the winter months.

Repetitive Motion Disorders

An epidemic of repetitive motion disorders is occurring in general industry. Possible causes include increased demands for production, out-of-shape workers, inadequate education on prevention of injuries, as well as poor tool design. Workers in swine industries frequently report similar problems.

Sources of injury in swine workers include lifting or moving swine, handling feed, and while vaccinating or bleeding swine. Improper lifting, bending or stooping frequently strains the muscles in the back. Occasionally the back pain may be so severe that the worker experiences lost work time. The workers should be adequately educated on proper lifting techniques, i.e., lifting at the knees without twisting while keeping the load close to the body. The use of back belts is controversial. Job rotation may be another option that allows muscles time to recover from overuse.

Frequent injections or bleeding of swine is associated with complaints of wrist or arm pain. If recovery time between these activities is insufficient and forceful, awkward postures are involved, then the risk for developing a repetitive motion disorder is high. Conditions such as tendinitis, tenosynovitis, and carpal tunnel syndrome may occur. To prevent these injuries from occurring, the worker should try to alternate hands and maintain their wrist in neutral positions. Knee pads will help decrease pressure on the knees. Hand stretching exercises may also be useful. There is a need for a multiple injection needle which can be reused and requires little force to work the equipment effectively.

Respiratory Health

Many swine workers have complaints of shortness of breath, cough, runny nose, eye irritation, and difficulty breathing. The longer a person works in a swine confinement building, the more likely he is to complain of these respiratory symptoms.

Numerous types of organic and inorganic dust, as well as several different gases, are present inside swine confinement buildings. Additionally, microorganisms, endotoxins, and mycotoxins are present. The dust comes from a variety of sources, including the feed, bedding materials, dried animal excrement, insect parts, and animal dander, to name a few. The dust can serve as either an irritant or occasionally an allergen. Symptoms from exposure include cough (16-67% of workers), nasal irritation (23-45%), phlegm (14-56%), eye irritation (8-39%), chest tightness (5-36%), and headaches (6-37%).

Numerous gases are also generated in confinement facilities. Gases of most concern include carbon monoxide, carbon dioxide, methane, ammonia, and hydrogen sulfide. Gases can irritate the airways causing similar symptoms as noted above. Additionally, gases may displace oxygen causing an oxygen depleted atmosphere which results in asphyxiation. Certain gases such as hydrogen sulfide may also interfere with oxygen utilization by cells causing a cessation of aerobic respiration leading to cell death. Methane may also be an explosion hazard.

The use of improperly ventilated power washers is a source of carbon monoxide, and manure pits are the primary source of hydrogen sulfide generation. Several deaths have occurred when workers have entered a manure pit without the appropriate respiratory equipment. Warning signs should be placed at the entrance to these pits. The National Institute of Occupational Safety and Health recommends a self-contained breathing apparatus and a buddy system when a worker plans to enter a manure pit.

Endotoxins and mycotoxins may be responsible for the condition known as Organic Dust Toxic Syndrome. This condition is similar to the flu with headaches, muscle aches, and fatigue occurring a few hours after working in a confinement building. The symptoms usually last from 24-48 hours and then resolve. Fortunately, there is no long-term problems, but repeated episodes may occur in the worker upon re-exposure to the swine confinement environment.

The use of a two-strapped dust mask will filter out most dust and microbes; however, dust masks are not effective for gases. Chemical cartridge respirators can be used for gas filtration; however, they are often bulky and may be difficult to use. Frequent use of dust masks may prevent respiratory illness from occurring. Only a self contained breathing apparatus should be worn when entering a manure pit or other confined space on the farm.

Another method to decrease dust and gas concentrations is by engineering controls. Properly operated fans and vents, the use of feed covers, and possibly certain feed additives can decrease the amount of dust produced. Gas-powered equipment should be properly maintained and ventilated. While no standard exists for exposure levels for dust and gas concentrations in swine confinement buildings, Dr. Kelly Donham has suggested the following levels as a goal to decrease the chance of developing disease.

While simple colorimetric devices are available to measure gas concentrations inside a swine confinement building, there are no simple devices available to measure dust and endotoxin levels. However, if the farmer notices problems in the herd or among workers, it is a good idea to have the levels determined and appropriate corrective factors instituted.

Take-Home Message

Individuals that work with swine are at risk of developing injury illness from their work. By following safety rules, using two-strap dust masks and ear plugs, avoiding entry into waste storage pits without a self-contained breathing apparatus, and by practicing good personal hygiene, most problems can be avoided. Research is currently being conducted on detection methods for gas concentration determinations that a farmer could easily utilize to evaluate air quality in the building.

Suggested Readings

1. American Lung Association of Iowa: livestock confinement dust and gases, agricultural respiratory hazards education series, unit IV, Ames, IA, Jan 1986.

2. National Institute for Occupational Safety & Health: preventing death of farm workers in manure pits, NIOSH Alert, Cincinnati, OH, May 1990.

3. National Institute for Occupational Safety & Health: NIOSH warns of deadly carbon monoxide hazard from using pressure washers indoors, NIOSH Update, Cincinnati, OH, May 1993.

4. Derthrick S., Bottcher R., Langley R., McLymore R.: Swine buildings and worker health, NC Cooperative Extension Service, Raleigh, NC, 1994.

5. National Institute for Occupational Safety & Health: Preventing organic dust toxic syndrome, NIOSH Alert, Cincinnati, OH, April 1994.

6. National Pork Producers Council: Making buildings a safer place to work, Des Moines, IA, 1991.

7. Duxbury-Berg L.: Producer recalls tragic tell of manure pit deaths, National Hog Farmer, May 1994.

8. Hafer A.: A detailed analysis of occupational health and safety hazards of swine veterinarians in United States, Masters Project, School of the Environment, Duke University, 1995.

9. Donham K., Reynolds S., Whitten P., Merchant J., Burmeister, Poppendorf W.: Respiratory dysfunction in swine production facility workers: dose-response relationship of environmental exposures and pulmonary function, Amer J Ind Med, vol 27(3), March 1995.