SELECTED HAZARDS AND PREVENTATIVE MEASURES
A variety of occupational health risks are associated with exposure to animals used in agricultural and biomedical research and education. These risks vary from the physical risks of chemical exposures, bruises, bites, kicks, scratches, ergonomic injuries, etc. to chemical exposure risks to infectious disease risks including those from zoonotic diseases (diseases transmitted from animals to humans) and experimentally induced diseases. The risk to individuals working with animals is related to the length and type of exposure, the species involved, and health status of the individual. Minimizing the risk to individuals involves specific design features of the facility, proper operating procedures, training, personal protective equipment, personal hygiene, vaccinations and an effective monitoring system.
Allergies
Among the most common occupational hazards associated with working with laboratory animals is the development of allergies. The prevalence of allergies in animal-care workers has been estimated from 10% to 44% while it is estimated that nearly 10% of all personnel working with laboratory animals will develop occupational asthma.
Several studies have suggested that persons with pre-existing allergic conditions, such as hay fever, are more likely to develop allergies to laboratory animals. While nearly 90% of personnel without any history of allergic reactions never develop allergies to laboratory animals, up to 73% of personnel with pre-existing allergic disease will develop allergies.
Most workers who develop allergic reactions to laboratory animals will do so within the first twelve months of working with them. Infrequently, reactions only occur after working with animals for several years. The initial symptoms are usually a running nose, nasal irritation, itchy eyes, and sometimes, rashes or urticaria (hives). Initially, the symptoms are present within minutes of the worker’s exposure to the animals. Approximately half of allergic workers will have their initial symptoms subside and then recur three or four hours following exposure. Approximately 10% of those developing this allergic rhinitis will eventually progress, with repeated exposure, to occupational asthma, which can result in chronic pulmonary disease even years after the exposure ceases.
| Species |
Allergen |
Source of Allergen |
Relative Risk |
| Rats |
Rat n 1A, Rat n 1B |
Urine |
+++++ |
| Mice |
Mus m1 |
Urine |
++++ |
| Guinea Pigs |
- |
Urine, dander, fur, saliva |
++ |
| Gerbils |
- |
- |
+ |
| Rabbits |
Glycoprotein |
Fur, saliva, urine |
+++ |
| Cats |
Fel d 1 |
Sebaceous glands, saliva |
+++ |
| Dogs |
Can f 1 |
Saliva, hair, skin |
++ |
| Nonhuman Primates |
- |
Dander |
+ |
| Pigs |
- |
Urine |
+ |
| Sheep |
- |
Lanolin? |
+ |
| Birds |
Protein |
Feces, serum |
+ |
The best method to minimize the potential for the development of allergies is to minimize exposure to the allergens. Ideally, this is accomplished by limiting the chances that workers will inhale or have skin contact with animal proteins. In addition to using well-designed air handling and waste management systems in research areas, workers can reduce their risk of exposure by routinely using dust/mist masks, gloves and gowns. If additional respiratory protection is required, the worker should contact Environmental Health and Safety.
Laboratory animal facilities are designed with relatively high air flow requirements, which reduce the concentration of allergens in the air by dilution. The control of the relative humidity to 40-70% also reduces the level of allergens in these rooms. Further allergen reduction is accomplished using individually ventilated caging (IVC) with the exhaust air passed through high efficiency particulate air filters (HEPA) to remove particulates and allergens. Animals removed from the laboratory animal facility to investigator laboratories are placed in environments which permit a much greater accumulation of allergens, potentially exposing personnel, including those not involved in the project, to higher levels of allergens. Holding soiled animal cages in the laboratory instead of immediately returning the cages to the animal facility for cleaning further increases exposure of personnel.
The greatest risk of exposure involves any activity that disturbs the bedding material of the animal generating airborne particles. Movement of the animals within the cage, whether normal activity or during manipulations, increases personnel exposure. Exposure can be minimized by the use of specialized bedding materials or, most effectively, by the use of containment caging such as microisolators, IVC’s, or filter tops. The use of personal protective equipment can also minimize exposure. Standard surgical masks are not effective although commercial dust respirators (N95) can significantly reduce exposure. Handling the cages and animals in laminar flow or biological safety cabinets can dramatically reduce the exposure of personnel.
If present at the time of hire, personnel with known allergies to laboratory animals should be evaluated by a physician through their personal insurance and reevaluated on a schedule determined by their physician based upon the clinical signs and symptoms. Pulmonary function tests should be performed to assess the severity of the disease and the progression, if indicated. Medical therapy may be prescribed to reduce or prevent the development of allergic symptoms. If symptoms of dermatologic or respiratory allergy and/or asthma develop during the course of employment, the employee shall file an incident report and a Workers’ Compensation claim through the employer’s insurance company. The Workers’ Compensation claims adjuster will determine where the employee shall go for evaluation and treatment. In all cases, however, exposure reduction and avoidance measures should be instituted. At a minimum, personnel with documented laboratory animal allergies should use a dust-mist respirator certified by the National Institute for Occupation Safety and Health (NIOSH). The Division of Environmental Health and Safety provides assistance in the choice of appropriate respirators and fit-testing when necessary. An alternative to the dust-mist respirator are the filtered airhood devices (Airstream Dustmaster® hood, Racal, Middlesex, UK or Bullard® PA30 Series Air-Purifying Respirator System) which have been shown to be very effective in allergen exposure reduction with increased operator comfort in certain situations.
Anaphylaxis is, fortunately, rare with laboratory animal allergies. Anaphylaxis may, however, occur in allergic personnel following an animal bite or puncture wound from contaminated needles. These situations, when they occur, are life-threatening emergencies requiring prompt medical treatment. Physicians may recommend that allergic personnel continuing to work with laboratory animals carry a self-administered form of epinephrine (e.g., Epi-Pen® or Ana-Kit®) and instruct co-workers in emergency procedures.
Animal Bites, Scratches, Kicks, etc.
Animal bites, scratches, and kicks are ubiquitous hazards whenever working with animals, either in the laboratory, or in other locations. Most of these injuries, however, are easily preventable with proper training and the use of appropriate animal handling procedures. Knowledge of species-specific animal behavior is important in predicting and responding to the animal’s reaction. It is essential, both for the animals and for the human handlers, that each person be properly trained and proficient at handling the animals under their care. New personnel should be fully trained and instructed before handling animals.
All personnel injured by animal bites, kicks, or scratches should immediately report the occurrence to their supervisor after the initial first aid procedures have been completed. All animal bites are potentially serious incidents because of the high potential for disease transmission and local infection from the animals contaminating oral flora. Medical attention should be sought in all but the most trivial injuries.
Chemical Hazards
A variety of chemicals are used in and around the animal facility including sterilants, disinfectants, alkaline and acid soaps, grease, insecticides, rodenticides, and various veterinary medical drugs, including volatile anesthetics. Proper handling of these chemicals is essential to prevent potential injury. Appropriate safety equipment including gloves, face protection, goggles, aprons, etc. should be worn whenever these chemicals are handled. Safety Data Sheets for all chemicals used should be readily available and preferably posted within the facility.
The Occupational Safety and Health Administration (OSHA) has promulgated two important safety standards that have focused attention upon chemical risks to workers, the Hazard Communication Standard (29 CFR 1910.1200) and the Occupational Exposure to Hazardous Chemicals in Laboratories (29 CFR 1910.1450). Additionally, National Research Council’s Commission on Physical Sciences, Mathematics, and Applications (CPSMA) published Prudent Practices in the Laboratory: Handling and Disposal of Chemicals (National Academies Press, Inc., 1995) providing extensive discussion on hazard assessment and control. Many factors influence the potential risk associated with any chemical exposure. These include the toxicity of the chemical or the chemical mixture (mixtures may be more toxic than the single most toxic component), the dose of exposure, the duration and/or frequency of exposure, and the route of exposure.
Flammability, corrosiveness, reactivity, and explosivity are generally well understood hazardous properties of chemicals. Toxicity is the least predictable and least understood property with the potential to cause immediate or delayed health effects. Chemicals handled in an animal research environment may be carcinogens, allergens, asphyxiants, corrosives, hepatotoxicants, irritants, mutagens, nephrotoxicants, neurotoxicants, and teratogens. Minimizing the exposure of personnel requires careful consideration of the routes of potential exposure that are associated with the animal care functions. Exposure routes include: (1) inhalation, (2) contact with skin or eyes, (3) ingestion, and (4) injection.
(1) The types of chemical toxins can enter the body via inhalation include gases, the vapors of volatile liquids, mists and sprays of both volatile and nonvolatile liquid substances, and solid chemicals in the form of particles, fibers, and dusts. The toxic effects vary from local damage to the lungs or mucous membranes to rapid circulatory absorption and systemic effects. Particles may be sequestered in the lungs with serious delayed long-term effects.
(2) Skin contact is a frequent mode of chemical exposure. Skin irritation and allergic skin reactions are a common result of contact with certain types of chemicals while corrosive chemicals can cause severe burns upon contact. In addition to causing local toxic effects, many chemicals are absorbed through the skin in sufficient quantity to produce systemic toxicity.
Few substances are innocuous in contact with the eyes; most are painful and irritating, and a considerable number are capable of causing burns and loss of vision. Alkaline materials, phenols, and strong acids are particularly corrosive and can cause permanent loss of vision.
(3) Many of the chemicals used in the laboratory are extremely hazardous if they are ingested. Caustic or irritating chemicals may produce lesions in the gastrointestinal tract tissues. Systemic toxicity requires the absorption of toxicants from the gastrointestinal tract into the circulation which may occur along the entire gastrointestinal tract, even in the mouth, and is dependent upon many factors, including the physical properties of the chemical and the speed at which it dissolves.
(4) Exposure to toxic chemicals by injection is fortunately rare. It can occur directly during procedural administrations or inadvertently through mechanical injury from "sharps" such as glass or metal contaminated with chemicals or when chemicals are handled with syringes. Non-laboratory personnel, such as custodial workers or waste handlers, must be protected from this form of exposure by putting all "sharps" in special trash containers and never in the ordinary scrap baskets.
Electricity
Electrical hazards are present wherever current is flowing. Electrical hazards in animal facilities are often accentuated by frequently wet or damp surfaces and the presence of various electrically operated machines. The use of moisture resistant electrical covers and ground-fault interrupter circuits greatly reduces potential accidental electrical injuries. The use of appropriate operation lock-out and tag-out procedures when performing maintenance on equipment greatly reduces electrical shock risks.
Ergonomic Hazards
Animal care personnel are required to handle and manipulate heavy loads and bulky materials throughout the workday. Handling large loads improperly or performing repetitive tasks may result in chronic injuries. Proper procedures for handling all heavy loads should be practiced and safety equipment and load assistance equipment used to reduce potential injuries. Environmental Health and Safety provides training sessions on the proper procedures for handling heavy loads. Employees with existing physical handicaps or injuries should consult with the occupational health physician and their workday procedures should be altered to prevent additional injury.
Health Precautions for Pregnant Personnel Working with Animals
Pregnant employees or those planning to become pregnant should contact their obstetrician/gynecologist immediately and specify that they work with animals. The species and types of activities involved (e.g., work with a particular infectious agent, chemical hazard, inhalant anesthetic, radioisotope, etc.) should be discussed so that one becomes educated about the associated risks and precautionary measures.
Impaired Immune System
Individuals with an impaired immune system, due to medication or disease, may be at a significantly greater risk of contracting an infectious disease from the animals with which they work. Such individuals should contact their personal physician and specify that they work with laboratory animals. One can also discuss this issue with the medical personnel associated with the OHSP who may, in turn, refer the enrollee to an occupational health physician.
Ionizing Radiation
Individuals are exposed to ionizing radiation on a daily basis as part of living on this planet (background radiation). Exposure to radiation in the animal care environment may result from irradiators, diagnostic veterinary x-rays, radioisotopes, and other sources. Appropriate procedures to minimize exposure and risk are based upon the type of radiation hazard and the possible methods of exposure. The use of ionizing radiation or radioisotopes is heavily regulated and under the oversight of Radiation Safety. The use of appropriate detection devices, personal protective equipment, and the use of proper procedures are all essential to minimize individual exposures and risks.
Machinery and Equipment
Tractors, tunnel washers, rack washers, autoclaves, pressure washers, floor polishers, compressed gas cylinders, etc., all pose potential risk to the operator or others if improperly used or maintained. Personnel using the equipment in the facility should be familiar with the proper procedures for use and follow standard procedures when using the equipment. Routine equipment maintenance is essential to ensure proper operation and minimal risk to the operator. The facility supervisor should be immediately notified if any piece of equipment is not functioning normally and the equipment should not be used until a determination of potential safety problems has been made.
Noise
Exposure to intense noise can and will result in impaired hearing. Chronic noise-induced hearing loss usually involves the higher pitched sounds, is permanent, and cannot be treated medically. The Occupational Safety and Health Administration limits employee exposure to noise to 90 decibels measured on the A scale of a standard sound-level meter at slow response (dBA) averaged over an 8-hour work shift (29 CFR 1910.95). Where levels exceed a time-weighted exposure of 85 dBA, the exposed employees need to participate in a hearing conservation program, administered through Environmental Health and Safety, that includes monitoring, audiometric testing, hearing protection, training, and record-keeping (29 CFR 1910.95 c-o).
In animal facilities, excessive noise can result from animals (especially pigs and dogs), cage-washing equipment, heavy agricultural machinery, and other equipment operated in enclosed environments. The construction requirements for ease of sanitation in animal facilities often accentuate the level of noise since sound-deadening material is nearly absent. Environmental Health and Safety monitors and documents the noise levels in specific areas where concerns exist and, if the levels exceed permissible thresholds, warning signs are posted. In areas where high noise levels are known to be present, employees should avail themselves of noise-protection equipment and limit their time of occupancy in the area.
Sharps
Needles, broken glass, syringes, pipettes, scalpels, scissors, etc. are all common in laboratory animal facilities and pose a hazard to personnel. Everyone working with animals has a responsibility to know how to handle potentially dangerous objects and how to properly store these items. Used needles, syringes, and scalpels should be disposed of in “sharps” containers located throughout the facilities. Personnel using needles and syringes should use care in the procedures and not recap any needle without consideration of the potential hazard of a needle injury. Except in rare instances, needles should be disposed of uncapped.
Zoonotic Diseases
Zoonoses are infectious diseases capable of being transmitted from animals to humans. Program participants are educated (assigned reading) on species-specific zoonoses pertinent to the species with which they work.
https://research.uky.edu/office-attending-veterinarian/zoonotic-diseases