2. HUMAN HEALTH RISKS ASSOCIATED WITH ANIMAL WORK
Workers in contact with laboratory animals may have frequent exposures to allergens in the form of dusts, fibres and animal products (hair, fur, dander, urinary proteins, faeces, and parasites). In susceptible individuals this can lead to various degrees of laboratory animal allergy (LAA). Signs of allergy include red, sore, watery or itchy eyes, running nose, sneezing, coughing, shortness of breath, and skin rash.
LAA may lead to Occupational Asthma (OA) if the primary symptoms are ignored. This type of asthma is 'work-related'. Once established, it will continue to be exacerbated by exposure to the 'trigger' allergens.
In addition to those who develop 'work-related' asthma, existing asthmatics who begin employment in animal-related work have a high risk of developing 'work-aggravated' asthma.
2.2 BITES, SCRATCHES AND KICKS
Persons working with animals are at risk of being bitten, scratched, kicked, butted, horned and stung by animals during handling. The risk of this is reduced if staff are trained in animal handling techniques. No person should work alone when handling primates.
2.3 ZOONOSES - DISEASES TRANSMISSIBLE FROM ANIMALS TO HUMANS
Laboratory animals of virtually all species can harbour infectious organisms which have the potential to cause disease in people; such a disease is termed a "zoonosis". It is important to realise that often such infections have no effect on their animal host, but can produce a serious zoonosis. Other such infections cause disease in both animals and people; common signs in animals include ill-thrift, sudden death, abortions, still births, spots or abscesses in internal organs, neurological signs etc. All staff should therefore be aware of the risk of zoonotic disease not only when handling animals, but also animal products such as cell lines, blood and excreta.
A disease may be spread by inhalation of infective dust or droplets, by ingestion, by contaminated food or water, or by penetration of skin or mucous membranes through cuts and scratches or by bites.
Working with primates may be a considerable risk as many of the primate diseases are transmissible to humans. Simian hepatitis B virus and tuberculosis are two such examples.
Feral rodents may be a source of zoonotic diseases and their elimination from animal houses and animal holding areas should be ensured.
Approximately 50 zoonoses have been reported in Australia. The most common species-associated zoonoses are included in Appendix 1.
2.3.1 RESPONSE TO ZOONOSIS
When the existence of a zoonosis is suspected both Laboratory Animal Services and WHS Services shall be contacted. Initially the location of the animals will be treated as if the zoonosis is present, and this status and restrictions will continue until tests have (either confirmed or) eliminated the possibility of a zoonosis. The relevant protocol will be followed as determined for the particular causal agent of the zoonosis. WHS Services will deal with the human health concerns and arrange for any prophylactic or further preventative measures. With the assistance of the unit concerned or department owning the animals, the OHS Office will attempt to locate any person who has been in the animal house or unit. Laboratory Animal Services will arrange for all the tests needed for diagnosis and will institute any further control measures concerning the animals. The Department or unit concerned will be responsible for expenses incurred for the tests and control measures.
The following precautions will be taken immediately without waiting for the results of diagnostic testing. The extent of the facility requiring quarantine/isolation will be defined. Access to the infected area shall be restricted to personnel defined as essential for the operation of the animal house by the officer in charge. Notices will be placed on all entrances warning that the area has been quarantined. This will warn any trades staff or visitors that the area has restricted access. Staff will be instructed to wear protective clothing including disposable gloves and face masks as appropriate to the suspected causal agent while working in the animal house. No material is to be removed unless going through the following procedures:
- Returnable containers such as bags shall be decontaminated before being returned, or else treated as disposable material.
- No food or other animal supplies are to leave the Animal House for use elsewhere.
- Disposable material such as animal bedding and wastes (including the gloves and masks and other disposable protective clothing) shall be doubled bagged for incineration or other type of relevant disposal and clearly marked with biosafety labels as per the University Hazardous Waste Disposal Guidelines.
- Contaminated footwear shall be either disposed of as contaminated material or scrubbed thoroughly using a liquid sterilising agent (removing all debris from treads and crevices) at the conclusion of the quarantine period.
- Laboratory coats, overalls or other protective clothing are to be wrapped in brown paper or other steam penetrable material to be autoclaved before going to the laundry. Heavily soiled clothing may be soaked in a disinfecting solution (e.g 1% bleach solution) to wash out some of the soiling material before autoclaving.
- Consideration should be given to wearing disposable protective clothing during the period of quarantine.
- Staff shall wash their hands with a disinfecting agent when leaving the quarantine area and maintain a high level of personal hygiene at all times.
- Exhaust air from the quarantine area may require additional high efficiency filtration to restrict spread of airborne organisms.
- Incoming materials (food, straw etc.) will be restricted to the minimum necessary for the care of animals until the zoonosis is eliminated.
These procedures may be modified to techniques most relevant to the causal agents once they have been positively identified.
Diseases notifiable under the NSW Stock Diseases Act and the NSW Exotic Diseases of Animals Act are to be reported to the NSW Department of Primary Industries by Laboratory Animal Services, regardless of zoonotic status. Diseases notifiable in humans shall be reported to the NSW Health Authority by the treating Occupational Physician in consultation with the OHS Office .
2.4 MANUAL HANDLING
Animal house work involves considerable manual handling (lifting and carrying cages, animals, and feed; pushing and pulling trolleys, bending and reaching to clean cages, etc). Such handling is associated with a significant risk of muscular sprain/strain injury, especially back pain.
Identification and assessment of the risk of injury requires consultation with the animal workers. Attention to the design of plant, equipment, the working environment (workspace, floors, etc) and work practices (including training) is required to fully examine the risk. For example deep sinks for cleaning may require considerable forward reaching and constant bending for some workers. Adding a hose to taps and/or fitting a tray to the bottom of the sink combined with training in safe work postures and practices will reduce the risk of long term back injury while improving comfort.
2.5 HAZARDOUS SUBSTANCES
Hazardous substances used in animal surgery or experimentation include anaesthetic gases, therapeutic and other chemicals (eg. cytotoxic drugs and radioactive materials). Unless used in the appropriate manner such substances may pose risks to persons handling and managing the animals.
Some disinfecting agents (e.g. formaldehyde, paracetic acid) are also toxic. Most skin disinfectants are capable of causing irritant or allergic dermatitis.
2.6 OTHER RISKS
Other risks associated with animal houses include slips and falls (especially in wet animla houses), burns from autoclaves, contact injuries from needles and sharps, and electrical hazards.