Background: Studies suggest that phthalate exposures may adversely affect child respiratory health.
Objectives: Evaluate associations between asthma diagnosed between child ages 5-11 years and prenatal exposures to butylbenzyl phthalate (BBzP), di-n-butyl phthalate (DnBP), di-2ethylhexyl phthalate (DEHP) and diethyl phthalate (DEP). Methods: Phthalate metabolites were measured in spot urine collected from n=300 pregnant inner-city women. Children were examined by an allergist or pulmonologist based on the first parental report of wheeze, other respiratory symptoms, and/or use of asthma rescue/controller medication in the last 12 months on repeat follow-up questionnaires. Standardized diagnostic criteria were used to classify these children as either having or not having current asthma at the time of the physician examination. Children without any report of wheeze or the other asthma-like symptoms were classified as non-asthmatics at the time of the last negative questionnaire. Modified poisson regression analyses were used to estimate relative risks (RR) controlling for specific gravity and potential confounders.
Results: 154/300 (51%) children were examined by a physician because of reports of wheeze, other asthma-like symptoms and/or medication use; n=94 were diagnosed with current asthma and n=60 without current asthma. The remaining n=146 children were classified as non-asthmatic. Compared to non-asthmatics, prenatal metabolites of BBzP and DnBP were associated with a history the asthma-like symptoms (p<0.05) and with the diagnosis of current asthma: RR 1.17 (95% CI: 1.01, 1.35) and RR 1.25 (95% C I 1.04, 1.51) per natural log-unit increase, respectively. Risk of current asthma was > 70% higher among children with maternal prenatal BBzP and DnBP metabolite concentrations in the 3rd versus 1st tertile.
Conclusion: Prenatal exposure to BBzP and DnBP may increase the risk of asthma among inner-city children. However, as this is the first such finding, results require replication.