Endotoxin in inner-city homes and atopy and wheeze in the first two years of life

Abstract

Rationale Studies have reported a protective effect of early life exposure to endotoxin against the development of allergic diseases, but few have examined an inner-city population. Due to temporal differences between increased hygienic living in NYC (early 20th century) and the asthma increase (later 20th century), we hypothesized that endotoxin's protective effect would not be observed in this inner-city community. Methods As part of an ongoing prospective birth cohort study sponsored by CCCEH, children of Dominican and African-American mothers living in NYC underwent detailed questionnaires quarterly, home dust collection, and IgE measurement. The 176 dust samples collected thus far from bedroom floors at age 12 months were extracted in pyrogen-free water with tween and assayed for endotoxin by LAL assay. Results The geometric mean of endotoxin in the dust was 78 EU/mg [95% CI 65-93]. Endotoxin concentrations were slightly higher in homes of mothers reporting weekly cockroach sightings (88 EU/mg vs. 72 EU/mg, p=0.3) or pet ownership (93 EU/mg vs. 75 EU/mg, p=0.4), and significantly higher with weekly mouse sightings (108 EU/mg vs. 69 EU/mg, p=0.043). There was no association between those children living in homes with endotoxin concentrations in the highest quartile (>163 EU/mg) and wheeze at 12 (RR 0.92 [0.8-1.1]) or 24 months (RR 0.96 [0.8-1.1]); doctor diagnosed eczema at 12 (RR 0.94 [0.8-1.1]) or 24 months (RR 1.0 [0.8-1.3]); or total IgE in the highest quartile at 24 months (RR 1.1 [0.8-1.5]). Conclusions At this age in this inner-city community we observed no association between high endotoxin and a lower prevalence of early markers of allergic disease, while endotoxin concentrations were comparable to those reported elsewhere.