Abstract
Inhaled endotoxin induces airway inflammation and is an established risk factor for occupational lung diseases. Prior studies suggested that higher levels of household endotoxin may be associated with asthma, wheeze, and medication use. The 2005-2006 National Health and Nutrition Examination Survey (NHANES) included evaluation of exposures to allergens and endotoxin to expand understanding of the relationships between allergic diseases and endotoxin. This represents the largest cohort study of endotoxin exposure ever done.
Subjects recruited on a national level were administered questionnaires in their homes. Reservoir dust was vacuum sampled to generate a composite bedding and bedroom floor sample. We analyzed 7450 NHANES dust and extensive quality assurance (QA) samples for their content of endotoxin using the kinetic chromogenic LAL assay. The entire study was done with extreme QA measures including use of a single lot of Limulus lysate. Data were weighted to match national demographics, were normalized by log transformation and were analyzed using backward stepwise regression and logistic regression. All but 3 samples were quantifiable and data for 6963 subjects were available.
Significant predictors of higher endotoxin exposures were lower family income; Hispanic ethnicity; presence of a child, dog, cat, cockroaches or smokers in the home; and carpeted floor. Endotoxin exposure was significantly associated with wheeze in the past 12 months, wheeze during exercise and use of prescription medications for wheeze.
Higher endotoxin exposure was associated with measures of wheeze but not with Dr. diagnosed asthma, asthma attacks in the past 12 months, nor asthma medication use.
- © 2014 ERS