«Occupational Health for Personnel Handling Laboratory Animals Hazards Associated With The Use Of Laboratory Animals* Working with laboratory animals, ...»
Occupational Health for Personnel Handling Laboratory Animals
Hazards Associated With The Use Of Laboratory Animals*
Working with laboratory animals, or tissues from laboratory animals, is associated with potential
health hazards to humans. These hazards include 1) bites, scratches, and kicks; 2) allergic
reactions; and 3) possible zoonotic diseases. The key to minimizing these hazards is
awareness and proper training. An on-line program titled “Occupational Health and Safety for
Personnel with Laboratory Animal Contact” is mandatory for all personnel with animal contact at Wright State University. This course MUST be satisfactorily completed prior to access to the Laboratory Animal Resources facility. The course addresses the risks associated with contact with laboratory animals and requires the completion of a short test at course conclusion to successfully register. The course is accessible at http://www.wright.edu/lar/LARsafety.htm.
Physical Hazards 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 in animal handling procedures and by proper procedures.
Knowledge of animal behavior is important in predicting and responding to the animal’s reaction.
It is essential, both for the animal's and for the human handler's sake 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 or scratches should immediately report the incident to their supervisor and the Department of Environmental Health and Safety after 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.
Sharps Needles, broken glass, syringes, pipettes, scalpels, scissors, etc. are all common in laboratory animal facilities and pose a hazard to personnel. Everyone in the laboratory animal facility 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 that are located throughout the laboratory animal 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 where a one-handed recapping technique is used, needles should be disposed of uncapped in the appropriate biohazard sharps containers.
Chemicals A variety of chemicals are used in the laboratory animal facility. These range from disinfectants, to alkaline and acid soaps, to grease. 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. Material Safety Data Sheets for all chemicals used in the Laboratory Animal Resources are available in the office and posted within the facility.
Tunnel washers, rack washers, autoclaves, floor polishers, etc., all pose potential risk to the operator or others if improperly used. Personnel using the equipment in the facility should be familiar with the proper procedures for use and follow standard procedures when using the equipment. The Laboratory Animal Resources 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.
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 85 dBA, the exposed employees need to participate in a hearing conservation program that includes monitoring, audiometric testing, hearing protection, training, and record-keeping (29 CFR
In a laboratory animal facility, excessive noise can result from animals (especially pigs and dogs), cage-washing equipment, and other equipment operated in enclosed environments. The construction requirements for ease of sanitation often accentuate the level of noise since sounddeadening material is nearly absent. In areas where high noise levels occur, employees should avail themselves of noise-protection equipment and limit their time of occupancy in the area.
Animal care personnel are required to handle and manipulate heavy loads and bulky materials throughout the workday. Laboratory personnel may also be involved in the handling of larger pieces of equipment for research purposes within the facility. Handling large loads improperly or performing repetitive tasks may result in chronic injuries. Proper procedures for handling all heavy loads should be adhered to and safety equipment and load assistance equipment used to reduce potential injuries. Employees with existing physical handicaps or injuries should consult with the occupation health physician and their workday procedures should be altered to prevent re-injury.
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 occupation-related 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.
The usual time from onset of work with laboratory animals and the development of allergies is between 1 and 2 years. The initial symptoms are usually a running nose, nasal irritation, itchy eyes, and sometimes, rashes. 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.
The best method to minimize the potential for the development of allergies is to minimize exposure to the allergens. Animal facilities have 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. Specialized caging systems include High Efficiency Particulate Air (HEPA) filtration systems to remove allergens from the exhaust air. 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.
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 or filter tops. The use of personal protective equipment can also minimize exposure. Standard surgical masks are not effective but N-95 commercial dust respirators can reduce the exposure up to 98%. Handling the cages and animals in laminar flow or biological safety cabinets can dramatically reduce the exposure of personnel.
Personnel with known allergies to laboratory animals should be evaluated by the occupational health physician and reevaluated on a schedule determined by the occupational health 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. 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. The Department of Environmental Health and Safety, Wright State University will provide appropriate respirators and fit-testing when necessary. An alternative to the dust-mist respirator is the filtered airhood device (Airstream Dustmaster® hood, Racal, Middlesex, UK), which has been shown to be effective.
Personnel with established allergies to laboratory animals are always at risk of exposure and the reoccurrence of severe disease. Generally this exposure occurs through contact with contaminated equipment or clothing, or inadvertent and unexpected exposure to the animals during transport. Personnel working with animals must be aware of this potential effect and take steps to minimize exposure of personnel outside the animal facility to allergens. These actions include the wearing of protective clothing (lab coats, etc.) in the animal facility, the transportation of animals in containers/cages designed to minimize allergen exposure (barrier cages), cleaning of equipment exposed to animals prior to removal from the animal facility, etc.
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.
Zoonoses are diseases transmitted between animals and man under natural conditions. These diseases, many of which are often relatively innocuous in their normal host, may result in serious or fatal diseases in abnormal hosts. With the number and range of potential zoonotic diseases, it is a reaffirmation of the validity of standard containment techniques that the number of zoonotic diseases transmitted between the laboratory research animals and the research personnel is so small.
B-Virus Infection (Cercopithecine Herpesvirus 1)
Host Range - Herpes B-virus produces a mild clinical disease analogous to the human Herpes simplex virus in macaques. The disease in macaques is characterized by lingual or labial vesicles or ulcers and often keratoconjunctivitis or corneal ulcers that are apparent for 1 - 2 weeks after the disease onset. As is typical of herpesviruses, a latency period follows with reactivation and expression of the virus (shedding) in monkeys during periods of physical or psychological stress. Several aberrant species, including humans, develop a severe and fatal encephalomyelitis when inoculated with the virus.
Transmission - Transmission of B-virus to man occurs primarily through bite or scratch wounds (saliva transmission) although cases of needlestick transmission, fomite (cage) transmission, and human to human transmission have been documented.
Clinical Signs - The incubation period varies from 2 days to 30 days with wide variation. A herpetiform vesicle may develop early at the site of inoculation. Early clinical signs include myalgia, fever, headache, and fatigue followed by a progression neurological disease with numbness, hyperesthesia, paresthesia, ataxia, confusion convulsions, and ascending flaccid paralysis.
Treatment - Antiviral treatment with acyclovir or ganciclovir is effective in controlling the viral disease but management is controversial since discontinuance of acyclovir therapy is associated with increasing serologic titers to B-virus. Therapy may be life-long.
Early diagnosis and intervention is critical in managing potential B-virus exposures. Serological samples should be obtained from the macaque and the patient as soon as possible after the bite. The patient's wound site and the macaque's conjunctiva and buccal mucosa should be cultured for virus isolation. The wound should be thoroughly cleansed and disinfected with a 0.5% sodium hypochlorite solution recommended for antisepsis.
Physicians should consult the Viral Exanthems and Herpesvirus Branch, Division of Viral Diseases, Centers for Disease Control and Prevention for assistance in case management.
Prevention - Protective clothing and equipment (face shield, mask, gloves, long-sleeved garments, etc.) when handling macaques is essential. While only serologically B-virus negative monkeys should be used to minimize potential exposure, no monkey should be considered Bvirus negative. Whenever possible, macaques should be anesthetized prior to any manipulations or handling where personnel may be at risk.
Lymphocytic Choriomeningitis (LCM)
Host Range - A member of the family Arenaviridae, this virus has a predilection for many rodent species and is common in wild mice throughout the world. A wide variety of laboratory animal species including mice, hamsters, guinea pigs, nonhuman primates, swine, and dogs can be infected with LCM but the laboratory mouse and hamster are the species of greatest concern with regard to transmission to man. The disease in laboratory mice and hamsters is usually clinically silent, and in the case of immunodeficient mice, may be undetectable with standard serologic techniques.