Metropolitan home living conditions associated with indoor endotoxin levels

Background: Household endotoxin exposure in allergy and asthma has been gai ning attention for its dual potential to exacerbate these conditions in ind ividuals with established disease and to abrogate atopy before disease onse t. Objective: We sought to better understand the home environmental and Lifest yle factors influencing house dust endotoxin levels, Methods: From the homes of 86 infants with wheeze in metropolitan Denver, C olorado, house dust endotoxin (detected with a standardized Limulus Amebocy te Lysate assay) and common indoor allergen (Fel d 1, Can f 1, Her p 1, Her f 1, and Bla g 1) contents were quantified. Comprehensive home environment and lifestyle questionnaires were completed during home visits by trained study staff and parents. Results: House dust endotoxin levels were associated with only 2 home envir onmental features: animals in the home and the presence of central air cond itioning. The strongest positive associations were found with animals in th e home, Interestingly,the homes without cats or other animals revealed a ne gative correlation between house dust Fel d 1 and endotoxin (P = .03), Cent ral air conditioning, especially during months of typical use, was associat ed with lower house dust endotoxin levels, No significant associations betw een house dust endotoxin levels and home dampness, number of household inha bitants or young children, cleaning frequency, or presence of tobacco smoke rs in the home were found, Conclusions: Indoor endotoxin exposure can be increased by the presence of animals in the home and decreased with central air conditioning, In some ho mes without animals, where allergen exposure adequate for sensitization sti ll occurs, there are lower levels of house dust endotoxin, Therefore in hom es without animals, factors that influence allergen and endotoxin levels in house dust probably differ, Households with detectable allergen levels but low endotoxin levels may provide a predisposing environment for animal all ergen sensitization.