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
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.