Occupational Health and Safety in Experimental Animal Facilities
The purpose of this module is to present information on working safely with animals in the course of research, teaching or testing.
Upon completion of the module, the reader will be able to:
- Understand the ways common laboratory animal species react, or defend themselves, if a procedure causes pain, or they perceive their safety to be threatened;
- Describe the pertinent aspects of safe handling and performance of manipulations;
- Describe the procedure for reporting animal related injuries;
- Identify the proper waste disposal procedures in animal facilities;
- Define zoonoses, and give examples of animal infections that can be transmitted to humans;
- Outline the levels of biohazard control, and methods used to minimize biohazard risks;
- Describe the sources of animal allergy; and
- Describe the procedures necessary to minimize exposure to animal allergens.
Index of topics
- Physical Hazards Associated With Experimental Animal Care and Use
- Safe Waste Disposal Practices in Animal Facilities
- Biological Hazards of Working with Experimental Animals - Zoonoses
- Biohazards as Part of Research Programs
- Laboratory Animal Allergy
- Chemical and Radiation Safety
Working safely with experimental animals encompasses not only the people and the animals, but also the facilities, equipment, and the procedures we use. It also encompasses the community in which we each live. We must each practice safe working habits to ensure that any health risks in our working environments never "leak" into the community because of faulty procedures or carelessness. The principal investigator must assume responsibility for ensuring that personnel working on the project are aware of any risks to health and safety.
Policies and programs required under provincial Occupational Health and Safety laws and regulations are implemented by each institution. Such institutional programs must support a safe working environment in animal facilities as well.
Avoiding Physical Injuries
Many tasks in animal facilities require moderate to heavy physical labour, and performing these tasks may expose personnel to risks from moving heavy equipment (strains), slippery floors, electrical hazards when washing, noise, etc. Each person must exercise due caution when performing such tasks.
Although the importance of understanding basic animal behaviour in the human/experimental animal interaction to avoid injuries can be emphasized here, it cannot replace the skills that are learned by working directly with the animals. Skilled animal care technical staff will already have the right attitudes and approaches towards animal handling and manipulations. They will also have the practical skills to do so safely and humanely. For others, some of the material presented here can serve as a useful introduction to handling animals safely in an experimental animal facility.
To work safely with an experimental animal a person should:
- understand basic animal behaviour in relation to their interactions with people during handling
- appreciate the "flight zones" typical of a species
- understand how to communicate with the animal
- use appropriate restraint techniques
- use restraint equipment properly
- identify any animals that may be unpredictable
- wear appropriate protective clothing and equipment
- maintain appropriate vaccination status
Basic Animal Behaviour Related to Handling and Manipulations
The flight zone is an animal's "personal space". The size of the flight zone varies with the tameness of the animal, and other animal-related factors. Completely tame animals have little or no flight zone and a person can touch them. An animal will begin to move away when the person enters the edge of the flight zone. When the person is outside the flight zone, an animal (or group of animals in a herd) will turn and face the person while maintaining a safe distance.
It is probably safe to say that when animals are in small cages or pens, all human "intrusions" are inside the animal's flight zone. Therefore, it is very important to condition the animals to regular handling to reduce the apprehension and stress imposed by human presence.
When an animal is apprehensive (e.g., about being picked up), aggressive (e.g., about to attack), or defensive (e.g., protecting itself, or its young in the case of a mother), its posture and other behavioural signs can give clues about its state and possible intentions. In many mammalian species the "warning" posture includes lowered head, ears down or back, and in the smaller animals, mouth open in a snarl.
By carefully observing the animal's behaviour while approaching it, injuries such as bites and scratches can be avoided.
Communicating With the Animal
Your voice, your touch, your smell, are all part of an animal's knowledge about you. To establish a two-way familiarity before a project starts, the people who will be handling or restraining the animals should talk to, touch, and regularly handle each animal. The conditioning period after transport to the laboratory (usually one or two weeks) is an excellent time to begin. Consistency in handling each animal is important. Most laboratory animals learn very quickly who their regular handlers or caretakers are, and accept the handling without undue stress.
Using Appropriate Restraint Techniques
Different species defend themselves in different ways. For example, a mouse, rat, hamster or dog may bite, a rabbit may struggle furiously and kick or sometimes bite to try and escape, a cat may scratch (with intent!) or bite; a cow or horse may kick. The approach to restraining the animal, including any equipment used for restraint, is to prevent the animal from taking such action while ensuring it is safely and humanely held. Although the correct approach to handling and restraint can be understood from printed and audio-visual materials, practice is essential.
Appropriate handling and restraint methods have been developed for most laboratory animal species. Skills in the appropriate handling and restraint methods should be attained BEFORE the research project starts.
The handling and restraint of non-human primates require special training, equipment and facilities. Please see the CCAC Guide to the Care and Use of Experimental Animals, Volume 1, 2nd Ed.. Chapter VIII Occupational Health and Safety.
Use of Restraint Equipment
For some procedures such as intravenous injection in a rabbit or blood sampling in a cow, restraint devices or equipment are useful adjuncts to the handling, and help ensure that the procedure can be done safely for both the animal and the person. Correct use of such restraint devices will help avoid unnecessary stress or injury to the animal during the procedure. Conditioning the animal to accept the restraint device is important to minimizing the risk of injury both to the animal and to the handler.
Use of Chemical Restraint
The safe handling of some species either in the laboratory, (e.g., some non-human primates) or in the field, may require the use of "chemical" restraint. Chemical restraint is the use of sedatives or anesthetics to control an animal's activity and thereby allow certain procedures to be done with minimal stress to the animal. Some of the drugs discussed in the analgesia and anesthesia sections of this course are useful for chemically restraining animals in circumstances where physical restraint represents a serious risk of harm to the animal or the handler, or is not feasible (e.g., many wild species).
Wearing Appropriate Protective Clothing
Protective clothing suitable for the handling to be done should be worn at all times; laboratory coats, coveralls, gloves, masks, boots (e.g., steel-toed for working with cattle), etc. As noted above, the handling of non-human primates is a special situation that requires special protective clothing.
Identifying Problem Animals
Any animal known to be difficult to handle should be so identified to all who might be working with it (e.g., weekend staff, veterinarian). As an old veterinarian once said, "I've never been bitten by a "biting" dog, but I've been bitten by lots of dogs that didn't bite".
Immunization of Staff
To minimize the risks associated with infections arising from any penetrating wounds such as animal bites or needle sticks, all persons working in laboratory animal facilities should maintain their tetanus vaccination status.
All persons at risk of exposure to rabies from any animals that may be infected, should consider vaccination for rabies. Any animals brought into experimental animal facilities that might have been exposed to rabies should be considered risks. Generally this refers to any domestic animals housed outdoors (including farm or fur animals), random source dogs and cats, and any wild animals. Institutions may require staff to have rabies vaccination as a condition of working with such species.
Depending on the species handled (e.g., non-human primates) other immunizations may be recommended as part of a health and safety program.
Appropriate records on the vaccination status of all employees should be maintained by the institution.
Animal-Related Injuries, Management and Reporting
Any animal-related injury that may be serious should be handled by the usual emergency medical care system. Apply the appropriate first aid, call an ambulance or get the injured person to a hospital emergency department.
Any minor injuries or incidents (e.g., a laboratory mouse or rat bite) should be handled by the appropriate first aid, and documented. Institutions usually have a procedure for documenting all injuries, including minor ones, in case complications develop later. The mechanism may be as simple as filing an incident report form.
Safe Waste Disposal Practices in Animal Facilities
Work in animal facilities commonly involves use of sharp instruments. All sharp items (e.g., needles, scalpels, capillary tubes, etc.) must be handled safely, and placed in designated sharps containers for disposal as per institutional policy. Needles should never be recapped and re-used.
Animal Waste Disposal
All animals, animal wastes and related materials should be disposed of as per institutional policy. Institutions commonly have a protocol defining proper disposal of all animal carcasses or organs. For example, this might involve collection of all such materials for incineration or other safe disposal. Disposal of non-contaminated waste (dirty bedding, feed, etc.) may differ from institution to institution. Adherence to animal facility waste disposal policies will minimize the risks to the community.
Biological Hazards of Working with Experimental Animals
Definition: The CCAC Guide to the Care and Use of Experimental Animals defines zoonosis as a disease of animals that may under natural conditions be transmitted to humans. What this really means is a disease that it is communicable between animals and humans.
The list of potential zoonoses related to working with animals in research, teaching or testing is quite long, and numerous books have been written on the subject. (See the CCAC Guide to the Care and Use of Experimental Animals, Volume 1, 2nd Ed.. Appendix VII Zoonoses). However, in reality the risks are very low when dealing with the common small laboratory animal species in the laboratory. There are several reasons for this low risk. Firstly, commercial suppliers of laboratory animals have done an excellent job of producing disease-free animals. As well, institutions generally have developed good occupational health and safety programs that include active veterinary monitoring and care programs.
The risk of exposure to zoonotic diseases is greater for those who work with experimental animals from random sources (including cats, dogs and most livestock), and for field researchers studying wild animals in their habitat. Working with non-human primates in the laboratory is a special case because of the many zoonotic concerns.
A few of the most common zoonoses in each of these areas of animal research will be presented as examples. For more information on zoonoses, and for more information about specific disease organisms, the Material Safety Data Sheets (MSDS) for individual organisms published by Health Canada Office of Laboratory Security can be consulted.
Routes of Exposure
Common routes of exposure to infectious organisms are:
- aerosol (inhaling the organisms)
- ingestion (swallowing the organisms)
- absorption through the skin, through mucus membranes or skin wounds
- injection (accidental, in research)
The use of appropriate equipment, including personal protective equipment appropriate to the route of exposure for a particular infectious organism, and appropriate practices, will minimize the risk of exposure.
Zoonoses Associated with Commercially Produced Laboratory Animal Species
As noted above, the risk of exposure to a zoonosis while working with common small laboratory animals that are commercially reared is very small. One example is presented here: Rat bite fever.
Rat Bite Fever
- Organism name, and synonyms: Streptobacillus moniliformis, a Gram-negative bacteria. Synonyms: Rat-bite fever, Haverhill fever.
- Reservoir: Rats. Commensal in the mouth and pharynx.
- Mode of Transmission: Animal bite, direct contact with secretions of the mouth, nose, eye of an infected animal.
- Incubation Period: 3-10 days.
- Clinical Disease: Initial bite wound usually heals. Sudden onset of fever, chills, vomiting, headache and joint pains, rash.
- Epidemiology: Uncommon in North America.
- Communicability: Not directly transmitted from person to person.
Zoonoses Associated with Random Source Laboratory Animal Species
Ringworm is a fungal infection of the skin that can occur in a wide range of animals including humans.
- Organism names, and synonym: Microsporum spp., Trichophyton spp., fungal organisms. Synonyms: Ringworm, dermatomycosis, tinea.
- Reservoir: Most domestic and wild animals, and humans. May be latent in hair of some species.
- Mode of Transmission: Direct or indirect contact with skin lesions or infected hair, or fomites (brushes, clippers, etc.).
- Incubation Period: 4-10 days.
- Clinical Disease: The fungi infect keratinized areas of the body - hair, skin and nails. Signs include round lesion of scaling skin, hair loss or breakage, sometimes reddened and crusting of infected skin.
- Communicability: Communicable from person to person when infective lesions are present.
- Diagnosis and Prevention: Monitoring for typical signs, confirmed by skin scrapings and culture. Many treatments are available.
Rabies can infect any mammal, including humans. Purpose-bred laboratory animals are not a likely source of rabies. However wild animals, animals obtained from random sources, or livestock, may carry rabies. Many institutions have rabies vaccination policies for at-risk personnel.
- Organism name, and synonym: Rabies - a rhabdovirus, Rabies, Hydrophobia.
- Reservoir: Wild and domestic animals (e.g., dogs, cats, foxes, coyotes, skunks, racoons) and bats.
- Livestock and rodents may be secondary hosts if infected by a biting animal.
- Mode of Transmission: Most commonly by a bite which introduces the virus from the saliva of a rabid animal. May be airborne in caves inhabited by infected bats.
- Incubation Period: Usually a few weeks, but may be up to a year or longer. The virus propagates in nerves. Thus the site of the wound (distance from the brain), presence of nerves at the wound, etc., influence the incubation period.
- Clinical Disease: Once clinical signs appear, the clinical course is short - usually less than 10 days with death due to respiratory paralysis. Signs include apprehension, behavioural changes, spasms of swallowing muscles, delirium, weakness progressing to paralysis.
- Epidemiology: Worldwide distribution with some rabies free areas. All mammals susceptible.
- Communicability: Infected animals shed virus for a few days before clinical signs appear. From then until the death of the animal, it is infectious.
- Diagnosis and Prevention: Pre-exposure immunization of all individuals at high risk (those who will handle animals, including laboratory workers, veterinarians and other animal handlers) should be used. The human diploid cell vaccine (HDCV) is currently used. Post-exposure treatment includes immediate first aid by generously flushing the wound and washing with soap and/or antiseptics, and providing post-exposure treatments as directed by the physician (e.g. rabies immune globulin, and vaccination).
Zoonoses Associated with Farm Animal Species
Q Fever may be contracted from working with sheep or goats, particularly ewes during lambing. The placenta and fetal fluids contain high levels of the organism in infected ewes.
- Organism name, and synonyms: Coxiella burnetii, an intracellular bacteria. Synonyms: Q Fever, Query fever, Rickettsia.
- Reservoir: Most common in sheep, cattle, goats. Infected domestic animals usually asymptomatic but shed massive numbers of organisms at parturition, in the placenta and placental fluids.
- Mode of Transmission: Direct contact with infected animals and their birth fluids; inhalation of organisms in dust from contaminated premises; wool from sheep.
- Incubation Period: Usually 2-3 weeks.
- Clinical Disease: Sudden onset fever, chills, headache, weakness, malaise, severe sweats; pneumonia, usually self-limiting. Chronic infection mainly involves endocarditis. Up to half of infections are asymptomatic.
- Epidemiology: Worldwide distribution. Occurs in laboratories using sheep for research; cases in research staff, exposed hospital patients.
- Communicability: Direct transmission from person to person very rare.
- Prevention: Use of appropriate protective clothing including masks. Serologic monitoring of ewes of limited value. Appropriate sanitation procedures. Vaccination available.
Zoonoses Associated with the Nonhuman Primates
As noted earlier, nonhuman primates are a potential source of many zoonotic diseases, and special facilities, equipment and procedures are required to work with them safely. The zoonosis discussed here - Herpes B infection - is the one that most people will have heard about.
Herpes B virus Infection
Herpesvirus simiae (B virus) causes a fatal ascending encephalitis in humans infected from old world nonhuman primates. The disease in the host nonhuman primates is usually mild or asymptomatic.
- Organism name and Synonym: Herpesvirus simiae, a DNA herpesvirus. Synonyms: B virus, Monkey B virus, Simian B disease.
- Reservoir: Common in old world monkey of the macaque group (most common in rhesus and cynomolgus macaques), both wild and captive colonies.
- Mode of Transmission: Latent infection in macaques with periodic episodes of oral lesions and shedding of virus in saliva. Transmission after a bite or direct or indirect contact with infected saliva or tissues. Laboratory infections from infected tissues can occur. Aerosol exposure minimal.
- Incubation Period: 3 days to a month.
- Clinical Disease: Acute, usually fatal, ascending encephalomyelitis; fever with headache, lesions at site of exposure. Death in 1 day - 3 weeks after onset of symptoms in over 70% of cases.
- Epidemiology: Occurs in veterinarians, laboratory workers and others handling old world monkeys or tissue cultures derived from these species.
- Communicability: Transmission from person to person rare.
- Prevention: Appropriate use of protective laboratory clothing (long sleeved lab coats, face shields or surgical masks and goggles or glasses), proper methods of restraint.
Zoonoses Associated with Wild Animals and Field Studies
- Organism name, and synonym: Hantavirus, an RNA virus in the Bunyavirus family. Synonyms: hantavirus, hantavirus pulmonary syndrome (HPS), Sin Nombre Virus (SNV) in North America.
- Reservoir: Wild rodents such as Peromyscus (deer mouse) and Microtus species in the Americas.
- Mode of Transmission: Inhalation of the virus in the dust from areas where infected rodent excreta (urine and feces) are present is the most common route. Rodent bites may transmit the disease.
- Incubation Period: Average two to four weeks but may be shorter or longer.
- Clinical Disease: Hantavirus Pulmonary Syndrome (HPS) is characterized by a sudden onset fever, pain, vomiting, and onset of respiratory distress and prostration. Mortality rates are high despite symptomatic treatment.
- Epidemiology: Occurs throughout much of North America including the western provinces.
- Communicability: Not thought to be communicable between persons.
- Diagnosis and Prevention: Use of personal protective equipment to avoid inhaling the dust particles with virus, and other direct contact in high risk areas should be used. Field biologists and persons working in previously "contaminated" buildings are at risk. Guidelines for protection against infection and for decontaminating facilities are available at the CDC (Centers for Disease Control and Prevention) web site.
Exposure Control Plans
Any circumstances that present particular risks of zoonotic infections should be identified before the risks are encountered. This includes immune compromised states (e.g., HIV infection, anti-rejections drugs or steroids, pregnancy, etc.).
Provincial Occupational Health and Safety regulations commonly define a requirement to develop a written "exposure control plan" for workers required to handle, use or produce an infectious material or organism or likely to be exposed. Responsibility for this rests with the employer. Such a written plan includes: identifying workers at risk, routes of infection, signs and symptoms of disease, vaccination, engineering controls, personal protective equipment, personnel training, safe work practices and procedures, dealing with accidents, and investigating accidents.
Biohazards as Part of Research Programs
When experiments are planned that will involve biohazardous agents, both the institutional occupational health and safety office, and Health Canada, Office of Laboratory Security Laboratory Biosafety Guidelines must be consulted. Material Safety Data Sheets (MSDS) are available for the individual organisms in the risk groups.
Biosafety Guidelines and Levels of Containment
Please note: the information provided here will give the reader a general understanding of the levels of biohazard control required to work with biohazardous agents safely in animal facilities. It is not intended to be definitive or complete.
Quote from the Health Canada Laboratory Biosafety Guidelines:
"The attitudes and actions of those who work in the laboratory determine their own safety, and that of their colleagues and of the community. Laboratory equipment and design can contribute to safety only if they are used properly by people who are genuinely concerned and knowledgeable about safety issues."
Biohazards are rated at four levels with a risk group associated with each level. Containment levels refer to the physical requirements and risk groups refer to the pathogenicity of the organisms. Biosafety Level 1 is required to manage the lowest risk and Biosafety Level 4 is required to manage the highest risk to human or animal health.
Biosafety Level 1
Risk Group 1 infectious agents are biological agents that are unlikely to cause disease in healthy workers or animals (low individual and community risk).
Facilities required to contain risk group 1 organisms - Containment Level 1: No special facilities, equipment or procedures are required. Standard well-designed experimental animal and laboratory facilities and basic safe laboratory practices suffice. Hand-washing facilities must be provided. Disinfectants must be properly used.
Biosafety Level 2
Risk Group 2 infectious agents are pathogens that can cause human or animal disease but, under normal circumstances, are unlikely to be a serious hazard to laboratory workers, the community, livestock, or the environment (moderate individual risk, limited community risk). Laboratory exposures rarely cause infection leading to serious disease; effective treatment and preventive measures are available and the risk of spread is limited.
Risk Group 2 infectious agents include, for example: E. coli; many salmonella; some fungi like ringworm; California encephalitis viruses; human herpes simplex viruses; many influenza viruses; Transmissible Gastro-enteritis of swine; Mouse Hepatitis Virus; and a few parasites.
Facilities, equipment, and procedures required to contain risk group 2 organisms at Level 2: Laboratory separated from other activities, biohazard sign, room surfaces impervious and readily cleanable. Equipment should include an autoclave, certified HEPA filtered class I or II biological safety cabinet for organism manipulations, and personal protective equipment to include laboratory coats worn only in the laboratory, gloves worn when handling infected animals. All contaminated material to be properly decontaminated.
Biosafety Level 3
Risk Group 3 infectious agents are pathogens that usually cause serious human or animal disease, or which can result in serious economic consequences, but do not ordinarily spread by casual contact from one individual to another (high individual risk, low community risk), or that can be treated by antimicrobial or antiparasitic agents.
Risk Group 3 pathogens include bacteria such as anthrax, Q Fever, tuberculosis, and viruses such as hanta viruses, Human immunodeficiency viruses (HIV - all isolates), eastern and western equine encephalitis viruses.
Facilities, equipment and procedures required to contain risk group 3 organisms include: Specialized design and construction of laboratories, with controlled access double door entry and body shower. All wall penetrations must be sealed. Ventilation system design must ensure that air pressure is negative to surrounding areas at all times, with no recirculation of air; air exhausted through a dedicated exhaust or HEPA filtration system. Minimum furnishings, all readily cleanable and sterilizable (fumigation). Laboratory windows sealed and unbreakable. Backup power available.
Equipment must include an autoclave, certified HEPA filtered class II biological safety cabinet for organism manipulations, and a dedicated handwashing sink with foot, knee or automatic controls, located near the exit. Personal protective equipment should include solid front laboratory clothing worn only in the laboratory, head covers and dedicated footwear, gloves worn when handling infected animals and appropriate respiratory protection, depending on the infectious agents in use.
Exit procedures should include showers, depending on infectious agents used and manipulations involved. All animal wastes to be disposed of as contaminated laboratory materials. All activities involving infectious materials to be conducted in biological safety cabinets or other appropriate combinations of personal protective and physical containment devices.
Laboratory staff must be fully trained in the handling of pathogenic and other hazardous material, in the use of safety equipment, disposal techniques, handling of contaminated waste, and emergency response. Standard Operating Procedures must be provided and posted within the laboratory outlining operational protocols, waste disposal, disinfection procedures and emergency response. The facility must have a medical surveillance program appropriate to the agents used, which includes serum storage for all personnel working in the containment laboratory and an accident report system.
Biosafety Level 4
Risk Group 4 infectious agents are pathogens that usually produce very serious human or animal disease, often untreatable, and may be readily transmitted from one individual to another, or from animal to human or vice-versa directly or indirectly, or by casual contact (high individual risk, high community risk).
Risk Group 4 infectious agents are all viruses, such as, Ebola viruses, Herpes B virus (Monkey virus), Foot and Mouth Disease.
Containment Level 4 is the highest level of containment and represents an isolated unit that is completely self-contained to function independently. Facilities are highly specialized, secure with an air lock for entry and exit, Class III biological safety cabinets or positive pressure ventilated suits, and a separate ventilation system with full controls to contain contamination.
Only fully trained and authorised personnel may enter the Level 4 containment laboratory. On exit from the area, personnel will shower and re-dress in street clothing. All manipulations with agents must be performed in Class III biological safety cabinets or in conjunction with one-piece, positive-pressure-ventilated suits.
Summarization of Biosafety Levels: Infectious Agents
- unlikely to cause disease in healthy workers or animals
- low individual and community risk
- examples: none
- can cause human or animal disease but unlikely to be a serious hazard
- moderate individual risk, limited community risk
- effective treatments available
- examples: E. coli, California encephalitis viruses, many influenza viruses
- cause serious human or animal disease but not ordinarily spread by casual contact
- high individual risk, low community risk
- examples: Anthrax, Q Fever, tuberculosis, Hantaviruses, Human immuno-deficiency viruses
- cause very serious human or animal disease, often untreatable and transmitted
- high individual risk, high community risk
- examples: Ebola viruses, Herpes B virus (Monkey virus), Foot and Mouth Disease
Summarization of Biosafety Levels: Facilities
- standard well-designed experimental animal and laboratory facilities
- as per Level 1, plus separate laboratory, room surfaces impervious and readily cleaned, biohazard sign
- as per Level 2, plus controlled access double door entry and body shower, air pressure must be negative at all times, no recirculation, HEPA filtration, backup power
- specialized, secure, completely self-contained unit with specialized ventilation, fully monitored; air lock entry and exit
Summarization of Biosafety Levels: Safety Equipment
- handwashing facilities, laboratory coats
- as per Level 1, plus autoclave, HEPA filtered class I or II biological safety cabinet, personal protective equipment
- as per Level 2, plus autoclave, HEPA filtered class II biological safety cabinet, personal protective equipment to include solid front laboratory clothing, head covers, dedicated footwear, and gloves, appropriate respiratory protection
- Class III biological safety cabinets, positive pressure ventilated suits
Summarization of Biosafety Levels: Procedures
- basic safe laboratory practices
- use of personal protective equipment laboratory coat worn only in the laboratory, gloves, decontamination
- staff fully trained, written protocols; showers, wastes disposed of as contaminated, use of biological safety cabinets, personal protective devices
- access only to certified staff, rigorous sterilization / decontamination procedures
Allergies to Laboratory Animals
Laboratory animal allergy (LAA) may be the most prevalent occupational hazard facing people working in experimental animal facilities. Surveys have revealed that up to 44% of people working with laboratory animals develop allergies to one or more species, and they usually become allergic within 3 years of first exposure (range; 1 month to 9 years).
Allergic reactions can be classified according to the site of the reaction: upper respiratory; lower respiratory; skin; generalized, anaphylactic.
In any individual, several symptoms may occur. The upper respiratory symptoms are the most common - up to 80% of affected people experience symptoms such as itchy, runny nose and eyes, and sneezing. About 20-30% of affected people experience lower respiratory symptoms, some progressing to occupational asthma. There is shortness of breath due to bronchoconstriction and airway mucus production. Asthma may become life-threatening if not treated. About 40% of laboratory animal allergic people experience skin reactions upon contact with the animal or the allergens. Much more rare, fortunately, is the acute generalized reaction (anaphylaxis) requiring emergency treatment. There are only a few documented cases of anaphylactic reactions to laboratory animal bites (e.g., rat bites).
Almost all species of common laboratory animals can trigger an allergic reaction. Allergies to the rat, rabbit, mouse, guinea pig, cat and dog are the most common.
The animal allergens are mostly small molecular weight proteins such as albumen. These proteins occur in the serum and tissues, but also in the saliva, urine and skin dander. When animals groom themselves, the salivary proteins also end up on the skin, and on the dander particles that flake off and become aerosolised.
Risk Factors for Becoming Allergic to Laboratory Animals
The risk factors for becoming allergic to laboratory animal allergens include atopy, smoking, gender and intensity of exposure.
There is a correlation between atopy (an inherited, familial tendency to develop some form of allergy such as hay fever, asthma, eczema) and the potential for developing LAA, and a stronger positive correlation between atopy and development of lower respiratory symptoms (asthma). Pre-employment health screening may be useful to identify atopic individuals.
Smoking reportedly does not increase the risk of developing LAA, but if a smoker does develop LAA, they are 1.5-3 times as likely to get the lower respiratory symptoms (asthma).
Males are more likely to be atopic than females (47% vs 37%) and so more likely to develop LAA.
There is a strong correlation between the intensity of exposure to the allergen, and the severity of symptoms. However, any allergen exposure, even very low levels, will trigger symptoms in allergic individuals.
Factors Affecting Animal Allergen Levels in Laboratory Animal Rooms
Ventilation and Relative Humidity
Directional room ventilation, negative flow laminar ventilated cage racks, or ventilated racks assist in reducing particles in room air. Low relative humidity results in higher dust and allergen levels. A relative humidity of 50-65% significantly reduces the quantity of allergen being aerosolized.
Type of Bedding
Studies have shown that sawdust/wood chip bedding results in higher levels of aerosolised allergen in rodent rooms than corncob bedding. Use of processed paper products and absorbent pads result in lower levels of aerosolised allergens.
Cleaning and Sanitation Practices
A high level of cleanliness results in reduced levels of allergens circulating in laboratory animal rooms.
Animal Room Tasks Associated with Exposure to Allergens
All commonly performed animal room tasks result in significant exposure to airborne allergens and dust. Cage cleaning (and waste dumping), animal care procedures (feeding, watering, etc.), animal manipulations (e.g., handling, injections), and general room cleaning all result in significant levels of airborne allergens.
Reducing Exposure to Allergens
There are several approaches to reducing exposure to laboratory animal allergens. Housing rodents in filtered cages and ventilated cage racks, use of ventilated waste dumping stations and laminar flow hoods for animal manipulations, will all help minimize exposure to laboratory animal allergens. Maintaining a high level of cleanliness, and using a bedding type that minimizes aerosol dust particles will also help minimize exposure to laboratory animal allergens.
The appropriate use of personal protective equipment such as good quality particulate masks and gloves can significantly reduce exposure to animal allergens. Such equipment should be provided for all staff required to work in high exposure areas. As well, good personal hygiene (regular hand washing, showering, etc.) should be practised.
There are several institutional responsibilities to minimize the impact of laboratory animal allergies. These include education programs for staff, health monitoring of at risk persons, improved engineering standards for ventilation and relative humidity, and provision of appropriate personal protective gear.
Education programs that cover topics such as symptoms, risks, defining risk zones and tasks, proper use of personal protective equipment, and health counselling for affected and at-risk staff, are very important.
Allergies to animals are nothing to sneeze at.
Experimental animal facilities routinely contain various chemicals such as detergents, disinfectants, anesthetics, tissue preservatives (e.g., formalin). Most staff will be familiar with safe work practices for use of these chemicals. A laboratory animal facility should be following the Canadian Workplace Hazardous Materials Information System (WHMIS), which consists of labelling chemicals, provision of material safety data sheets (MSDSs) and employee education programs. A detailed discussion of all the chemicals used in experimental animal facilities, their hazards and safe use is beyond the scope of this module.
Institutions will already have a program in place to ensure work with ionizing radiation, including isotopes injected into animals as part of their research use, is done safely. Training and licensing of users and facilities are mandated. A detailed discussion of the use of radiation in experimental animal facilities, their hazards and safe use is beyond the scope of this module.
Remember: YOU are the primary person responsible for working safely in your laboratory animal facility!
Canadian Council on Animal Care. Guide to the Care and use of Experimental Animals, Volume 1, 2nd Ed. 1993. Chapter VIII Occupational Health and Safety.
National Research Council. 1997. Occupational Health and Safety in the Care and Use of Research Animals. ILAR, CLS, NRC. National Academy Press, Washington, DC 154p. Available for reading online at the National Academies Press website.