Reported March 2006

BACKGROUND: Bacteria lurking in household dust produces chemicals that may trigger asthma symptoms, whether a person suffers from asthma or allergies or not. The results, from the first nationwide study of toxins made by bacteria in households, indicate that it's not just the concentration of the bacteria-made toxin that is important. Other factors, such as how long and when a person is exposed to the bacterial toxin, as well as genetic factors, may contribute to the development of asthma.

THE STUDY: The nationwide study involved the analysis of more than 2500 dust samples from 831 homes across the United States. Results show a strong association between the levels of toxins made by bacteria -- called endotoxins -- and the prevalence of diagnosed asthma, asthma symptoms and wheezing. People in households with higher endotoxin concentrations had higher instances of respiratory symptoms.

ABOUT ENDOTOXINS: Endotoxins are found in the cell wall of bacteria and are only released when the cell ruptures or disintegrates. Because bacteria can be found everywhere in the home, the likelihood of such a release is very high. Once released, endotoxins can cause inflammation of the airways and lead to asthma symptoms. Endotoxin levels can be reduced in the same way that allergy symptoms can be reduced: by removing dust, keeping the floors as clean as possible, keeping moisture low, repairing water damage, cleaning bed linens, and using a high-efficiency vacuum cleaner with a HEPA filter, among other actions.

ASTHMA OR ALLERGIES? Asthma is a chronic disease affecting the airways that carry air in and out of the lungs. The inside walls of the airways become inflamed (swollen) and narrower so less air can flow through the lung tissues. This in turn causes wheezing, coughing, tightness in the chest, and trouble breathing. Asthma is linked to allergies, although not everyone with asthma has allergies. People with allergies tend to react more strongly to the presence of allergens such as animal dander, dust mites, pollen or mold, as well as cigarette smoke and air pollution.

If you would like more information, please contact:

Peter Thorne, PhD, Environmental Toxicologist
Department of Occupational & Environmental Health
University of Iowa
319-335-4216
peter-thorne@uiowa.edu

For more information about microorganisms, asthma and allergies, contact:

American Society for Microbiology
1752 N Street, N.W.
Washington, D.C. 20036-2904
(202) 737-3600
http://www.asm.org/

FACTOID...

Around 15 million people in the United States -- roughly 5 percent of the population -- suffer from asthma, and nearly 5 million of those are children.

ON THE WEB...

Check out the research!