Placental levels of halogenated organic compounds and cord blood immune markers

Background: Intrauterine exposures to halogenated organic compounds (HOCs) such as polychlorinated biphenyls (PCBs) and dichlorodiphenyldichloroethylene (DDE) are related to a diversity of childhood manifestations including asthma, growth retardation, infection, and early age at menarche. In addition, polybrominated diphenylethers (PBDEs) became of interests as new emerging toxicants. To understand the mechanisms involved, we have been conducting an investigation that starts in the first trimester of pregnancy and then follows mother-infant pairs. Methods: The pregnancy, environment, and child health (PEACH) study focuses on exposure to HOCs and immune processes involved. We gather maternal serum, placental, and breast milk samples to measure and compare exposure levels. We collect cord blood and breast milk samples to quantify immune markers such as cytokines and immunoglobulins. Data are analyzed with linear and logistic regression controlling for confounders. Results: Maternal serum levels of HOCs, placental, and breast milk concentrations are only weakly correlated and cannot substitute each other. Increased placental p,p'-DDE is associated with a statistically significant increase in cord plasma interleukin (IL)-13 and with an increase in cord plasma of both IL-4/INF-gamma and IL-13/INF-gamma ratios. Increased levels of IL-4 and IL-13 in cord blood are known to be related to increased propensity for allergic diseases. Neither maternal nor breast milk HOC levels are associated with immune markers determined from breast milk. Conclusion: Placental HOC exposure is likely to explain a higher susceptibility for allergic manifestations in childhood.