Health and Safety

If you work with laboratory research animals you probably know that animal allergies are still one of the most common health hazards faced each day. Although this topic has garnered lots of research attention, allergic reactions, which are a result of immunological and biochemical mechanisms, are not totally understood. And so laboratory animal allergy (LAA) remains a serious occupational hazard. Did you know that approximately one-third of laboratory animal workers have an occupational allergy to animal danders?¹ Or that, one-third of these have symptomatic asthma?^1,2 In fact, about three-quarters of workers with preexisting allergic disease (referred to as the atopic risk group) eventually develop a laboratory animal allergy.² Given these statistics and the potential seriousness, especially if LAA should progress to asthma, we thought it is time to provide some reminders for prevention.

Risk Factors and Symptoms
Laboratory animal allergy begins with exposure to the allergens which are usually proteins or glycoproteins. Animal allergens are found in urine, saliva, dander, and fur of most research species including rats, mice, cats, dogs, horses, and birds among others. The exposure route is most often airborne allergens but skin contact can also produce reactions of a different kind. Most workers that develop LAA do so within one to three years of first exposure.¹ Persons with allergic conditions such as hay fever are at greater risk in developing LAA as atopic individuals are eleven times more likely to become sensitized to animal allergens than non-atopics.¹ In addition, atopy may reduce the time for developing LAA and increase the severity should an atopic worker become sensitized. One study found the median time from first exposure to symptoms of LAA was 2.2 years for atopics compared to 8.2 years for non-atopics.¹

Other risk factors include the duration of exposure and allergen concentration. Airborne allergen concentrations are directly proportional to the number of animals in the area and depend on the rate of production and the rate of removal. This suggests that ventilation is central in limiting exposures. However, at least one study has shown that although ventilation is effective for lowering concentrations when allergen production is low (i.e. small numbers of animals), it might take up to 127 air changes per hour (ACH) to significantly reduce exposures when allergen production is very high such as during cage cleaning or in densely populated areas.²

Experience shows that exposure concentrations are definitely related to specific tasks as well. Cage-cleaning ranked at the top followed by handling and then surgery/euthanasia. Research has shown that airborne allergen concentration increased up to five times and small particles (less than 1 micron average diameter) increased three times in areas where cage cleaning was conducted. Sampling methods are available to measure airborne allergen concentrations as well as particle size. This is very useful information to have and it is important to keep these facts in mind when developing your prevention program.

Laboratory animal allergy usually begins with nasal symptoms like sneezing and a runny nose, itchy, watery eyes, and/or rashes. A more serious condition that might affect about ten percent of workers is occupational asthma that can cause coughing, wheezing, and shortness of breath and lead to chronic symptoms that continue even after exposure is removed.