Endotoxins in House Dust Linked to Asthma

The investigators took 2,552 house dust samples from five locations within the home, including bedroom floors, bedding, family room floors, sofa surfaces, and kitchen floors.

The authors found that the strongest relationship between asthma, asthma medications, and wheezing came from endotoxin levels in bedroom floor and bedding dust. This was true despite the fact that endotoxin concentrations were highest in kitchen and living room floor dust, and lowest for bedding (including mattress and pillow). However, the effects were observed only in adults and not in children.

No effect was observed of allergy status on the relationship between endotoxin and asthma outcomes. This suggests that current endotoxin exposure may have little impact on allergy status and that airway inflammation is the most significant effect of endotoxin exposure in a cross-section of the population. The study appeared in the first issue for December 2005 of the American Journal of Respiratory and Critical Care Medicine.

Endotoxins are toxic substances associated with the outer membrane of certain Gram-negative bacteria. These molecules are bound to the bacterial cell wall and are released when the bacterium ruptures or disintegrates.

"This study clearly demonstrates significant relationships between household endotoxin and diagnosed asthma, recent asthma symptoms, current use of asthma medications, and wheezing,” said Dr. Peter S. Thorne, Ph.D., of the environmental health sciences research center at the University of Iowa (Iowa City, IA, USA), who led the study.




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