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Organochlorine Exposures During Pregnancy and Infant Size at Birth

Background: Organochlorines, including polychlorinated biphenyls (PCBs) and pesticides, are environmentally persistent contaminants that concentrate in the food chain as well in human adipose tissue and readily cross the placenta. Methods: To follow up on studies suggesting an association of organochlorine exposure with reduced birth size, we investigated the association of PCBs and organochlorine pesticides (including p,p′-dichlorodiphenyl dichloroethene [p,p′-DDE], the major degradation product of p,p′-dichlorodiphenyl trichloroethane [p,p′-DDT], and hexachlorobenzene [HCB]), with birth weight, crown-heel length, and head circumference. We evaluated a cohort of 722 infants born between 1993 and 1998 to mothers residing near a PCB-contaminated harbor and Superfund site in New Bedford, Massachusetts. Results: Small negative associations were observed for PCBs and birth weight; associations were weaker for birth length and head circumference. There was evidence for effect modification by smoking during pregnancy on the association between PCBs and birth weight. No associations were found with p,p′-DDE or HCB for any measures of birth size. Conclusions: This study supports the growing literature that demonstrates at most a weak association between very low-level organochlorine exposure and birth size.