Allergens | Aeroallergen

Prepared by: Michael J. Huerkamp, DVM, Diplomate ACLAM
Date: February 1, 2001

Agent: Allergens, aeroallergens

Potential Hazard: Occupation-associated allergies to research animals and to latex are of greater concern for animal resources personnel today rather than exposure to zoonotic pathogens. Ten percent of asymptomatic individuals will develop hypersensitivity to rodent allergens following sufficient exposure. Seventy percent of those with pre-existing allergies will become sensitized to rodents. Sensitization involves risk of rhinitis, contact urticaria (hives) and asthma. Symptoms may not appear for up to a year after exposure. The major sources of rodent allergens are the saliva, hair and urine. Rodent dander and bedding are significant sources of allergens which can be transmitted by aerosol, environmental contamination, and soiled clothing. In disturbed air, such as that occurring during cage changing procedures or when removing a fractious animal from a cage, allergen levels can increase five fold and persist in the air for a half-hour or more.

Mice, rats, guinea pigs, rabbits, birds, and, to a lesser extent, dogs and cats are the most common source of animal-related allergy. Swine, sheep, fish, reptiles, and nonhuman primates are rarely incriminated. Male mice are more allergenic than females.

Recommended Precautions: Personnel handling rodents or other research animals should wear gloves and laboratory coats or a gown. For purposes of protecting others, street clothes alone should not be worn into animal colonies or when handling animals. Rodents, their soiled cages or waste should not be transported in public elevators or corridors. Mice should be housed in filter top cages accessed only in a properly filtered laminar air flow hood. Wearing personal protective equipment as prescribed by a physician, such as a respirator, will aid in protection from allergens, but requires fit and pulmonary function testing. It should be noted that surgical-type masks will not protect animal handlers from airborne allergens. Persons developing hives after wearing latex gloves or handling rodents or a runny nose or more severe symptoms should report such to their supervisor and to Employee Health.

The animal research facilities have been designed and practices continue to be refined to manage allergens. All air used to ventilate the animal research facilities is 100% fresh, not recirculated, and moved at high volume so as to dilute allergens, pollutants and other undesirable agents. Ventilated caging systems, used to house mice and some rats, have the exhaust air from cages filtered before returned to the room. Newer generation cages, to be deployed in the Whitehead and other buildings, will exhaust cage effluent directly from the room and building and not back into the room.

References: Bush, Robert K. Laboratory Animal Allergy. National Symposium on Biosafety 2000; pp. 109-113. Occupational Health and Safety in the Care and Use of Laboratory Animals, NRC, Washington, DC, 1997, pp. 51-64.