Detectable levels of dog and cat allergens are universally present in U.S. homes

Scientists at the National Institute of Environmental Health Sciences (NIEHS), one of the National Institutes of Health, and the U.S. Department of Housing and Urban Development have found that detectable levels of dog and cat allergens are universally present in U.S. homes.

Although allergen levels were considerably higher in homes with an indoor dog or cat, levels previously associated with an increased risk of allergic sensitization were common even in homes without the pets.

This report by Arbes et al., which will appear in the July 2004 issue of the Journal of Allergy and Clinical Immunology, is one of a series of allergen reports from the National Survey of Lead and Allergens in Housing. In that nationally representative survey of 831 homes, researchers collected dust samples, asked questions, and examined homes.

Interestingly, the researchers found that dog and cat allergen levels were higher among households belonging to demographic groups in which dog or cat ownership was more prevalent, regardless of whether or not the household had the indoor pet. Because dog and cat allergens can be transported on clothing, the researchers speculated that the community, particularly communities in which dog or cat ownership is high, may be an important source of these pet allergens. For pet-allergic patients in such communities, allergen avoidance may be a difficult challenge.

The survey was conducted using established sampling techniques to ensure that the surveyed homes were representative of U.S. homes. The homes were sampled from seventy-five randomly selected areas (generally counties or groups of counties) across the entire country. The 831 homes included all regions of the country (northeast, southeast, midwest, southwest, northwest), all housing types, and all settings (urban, suburban, rural). For statistics derived from the 831 homes, the contribution from each home was weighted as necessary to ensure that the statistics were representative of the U.S. population. Until now, exposure to these allergens had not previously been studied in residential environments on a national scale.