Prenatal Exposure to Butylbenzyl Phthalate and Early Eczema in an Urban Cohort

Background: Recent cross-sectional studies suggest a link between butylbenzyl phthalate (BBzP) in house dust and childhood eczema.

Objectives: To evaluate whether monobenzyl phthalate (MBzP), the main BBzP metabolite in urine, during pregnancy is associated prospectively with eczema in young children, and whether this association varies by the child’s sensitization to indoor allergens or serological evidence of any allergies.

Methods: MBzP was measured in spot urine samples during the 3rd trimester of pregnancy from n=407 African American and Dominican women residing in New York City in 1999-2006. Repeated questionnaires asked mothers whether their doctor ever said their child had eczema. Child blood samples at ages 24, 36, and 60 months were analyzed for total, anti-cockroach, dust mite, and mouse IgE. Relative risks (RR) were estimated with multivariable modified Poisson regression. Analyses included a multinomial logistic regression model for early and late onset eczema versus no eczema through age 60 months.

Results: MBzP was detected in >99% of samples (geometric mean 13.6, interquartile range 5.7, 31.1 ng/ml). By 24 months, 30% of children developed eczema, with the proportion higher among African Americans (48%) than Dominicans (21%) (p<0.001). An interquartile range increase in log MBzP concentration was associated positively with early onset eczema (RR 1.52 for eczema by 24 months, 95%CI: 1.21, 1.91, p=0.0003, n=113 reporting eczema / 376 total sample), adjusting for urine specific gravity, sex, and race/ethnicity. MBzP was not associated with allergic sensitization, nor did seroatopy modify consistently the MBzP and eczema association.

Conclusions: Prenatal exposure to BBzP may influence the risk of developing eczema in early childhood.

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