Prenatal Exposure to DDE and PCB 153 and Respiratory Health in Early Childhood A Meta-Analysis

Background: Persistent organic pollutants may affect the immune and respiratory systems, but available evidence is based on small study populations. We studied the association between prenatal exposure to dichlorodiphenyldichloroethylene (DDE) and polychlorinated biphenyl 153 (PCB 153) and children's respiratory health in European birth cohorts. Methods: We included 4608 mothers and children enrolled in 10 birth cohort studies from 7 European countries. Outcomes were parent-reported bronchitis and wheeze in the first 4 years of life. For each cohort, we performed Poisson regression analyses, modeling occurrences of the outcomes on the estimates of cord-serum concentrations of PCB 153 and DDE as continuous variables (per doubling exposure) and as cohort-specific tertiles. Summary estimates were obtained through random-effects meta-analyses. Results: The risk of bronchitis or wheeze (combined variable) assessed before 18 months of age increased with increasing DDE exposure (relative risk [RR] per doubling exposure - 1.03 [95% confidence interval = 1.00-1.07]). When these outcomes were analyzed separately, associations appeared stronger for bronchitis. We also found an association between increasing PCB 153 exposure and bronchitis in this period (RR per doubling exposure = 1.06 [1.01-1.12]) but not between PCB 153 and wheeze. No associations were found between either DDE or PCB 153 and ever-wheeze assessed after 18 months. Inclusion of both compounds in the models attenuated risk estimates for PCB 153 tertiles of exposure, whereas DDE associations were more robust. Conclusion: This large meta-analysis suggests that prenatal DDE exposure may be associated with respiratory health symptoms in young children (below 18 months), whereas prenatal PCB 153 levels were not associated with such symptoms.