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Pet Allergens Found in All U.S. Homes

Even those that don't have animals, study finds

THURSDAY, July 8, 2004 (HealthDayNews) -- The truth about pet dander is it may be more ubiquitous than you think.

Regardless of whether a dog or cat is in permanent residence, all homes in the United States contain dog and cat allergens, a new study claims. As a matter of fact, pet dander was present in almost 100 percent of the homes surveyed, even though dogs and cats only lived in half of those residences.

"Folks' sensitivity to cat and/or dog allergens are in all likelihood going to be exposed to detectable levels of those allergens in their environment regardless of where they live," said Dr. Darryl Zeldin, head of the asthma research program at the National Institute of Environmental Health Sciences (NIEHS). He is senior author of the study, which appears in the July issue of the Journal of Allergy and Clinical Immunology.

Such allergens are believed to contribute to asthma.

The researchers used data from the first National Survey of Lead and Allergens in Housing, which had been gathered in 1998 and 1999. The surveyors collected vacuumed dust samples from the bed, bedroom floor, living room floor and living room sofa in 831 housing units containing 2,456 people in 75 locations around the United States.

Dog and cat allergens were detected in 100 percent and 99.9 percent of homes, respectively, even though only 49.1 percent of the homes actually had such a pet. Most of the homes surveyed had levels that surpassed the proposed thresholds.

Sofas had the highest concentration of dog and cat allergens, indicating either that the pet ruled the house or the allergens rubbed off human clothing.

It's also likely allergens will be lower in communities where dog and cat ownership is less common, such as inner cities, Zeldin added.

Why would these allergens be found in homes without cats or dogs?

"One explanation is that the cat and dog allergies are transported on clothing," said Samuel J. Arbes, lead author of the study and clinical research coordinator at the NIEHS. "It's been shown that dog and cat allergens are present in public places -- on bus seats, in taxis, on park benches, in movie theaters, in hospitals, and even in the offices of allergists." This means they can easily be picked up and taken back home.

It's also possible that a pet lived in the house in the past.

The upshot is that reducing exposure to allergens may not be the most efficient route to controlling asthma and allergies. "For people who are allergic to dogs and cats, allergen avoidance may be very difficult, and it may be that people who are very allergic to dogs and cats may have to rely on medications as opposed to trying to avoid exposure," Arbes said.

"So long as the allergens are ubiquitous in communities, it can be very difficult for folks to avoid those allergens," Zeldin said. "Perhaps the approaches should not be on environmental intervention per se, but on other types of ways to modulate the response of an individual to those exposures such as medications, immune therapy or allergy shots."

According to Dr. Michael Marcus, director of allergy, immunology and pediatric pulmonology at Maimonides Medical Center in New York City, decreasing exposure should still help, but it's also necessary to focus on the underlying disease responses, especially because different people have different tolerance levels.

"We have to understand the underlying disease better, whether we're talking about allergic rhinitis or eczema or asthma," he said. "We need to look at the basic problem of the disease instead of trying to avoid the triggers of the disease as the only way of dealing with it."

More information

For more on asthma and allergy prevention, visit the National Institute of Environmental Health Sciences.

SOURCES: Samuel J. Arbes, Jr., D.D.S., M.P.H., Ph.D., epidemiologist and clinical research coordinator, National Institute of Environmental Health Sciences, Research Triangle Park, N.C.; Darryl Zeldin, M.D., head, asthma research program, National Institute of Environmental Health Sciences, Research Triangle Park, N.C.; Michael Marcus M.D., director, allergy, immunology and pediatric pulmonology, Maimonides Medical Center, New York City; July 2004 Journal of Allergy and Clinical Immunology
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