Researchers at NIEHS and the University of Iowa found a strong association between endotoxin levels and the prevalence of diagnosed asthma, asthma symptoms, asthma medication use, and wheezing. These relationships were strongest for bedroom floor and bedding dust. Households with higher endotoxin concentrations experienced higher prevalence of respiratory symptoms.
Endotoxins are found in the cell wall of bacteria and are only released when bacteria ruptures or disintegrates. Because bacteria can be found everywhere in the home, the likelihood of their release is high. Once released, endotoxins can cause inflammation of the airways and lead to asthma symptoms.
The study, published online in the American Journal of Respiratory and Critical Care Medicine, was conducted using samples from The National Survey of Lead and Allergens in Housing (NSLAH).
Two research assistants visited each household, administered a detailed questionnaire, conducted a home inspection, and used a standardized protocol to collect samples. Dust samples were collected from bedroom, kitchen and living room floors, bedding, and upholstered furniture and assayed for endotoxin. A disease association analysis was performed to correlate endotoxin concentrations to specific health outcomes.
“When we analyzed the dust samples, we found that kitchen and living room floors had the hig