Lactational exposure to polybrominated diphenyl ethers and its relation to social and emotional development among toddlers.

BACKGROUND: Polybrominated diphenyl ethers (PBDEs) have been widely used as flame retardants and are ubiquitous environmental contaminants. PBDEs have been linked to adverse neurodevelopment in animals and humans.

OBJECTIVES: We investigated the association between breast milk PBDE levels and social and emotional development in toddlers.

METHODS: The Pregnancy Infection and Nutrition (PIN) and PIN Babies studies followed a cohort of North Carolina pregnant women and their children through 36 months of age. Breast milk samples obtained at 3 months postpartum were analyzed for PBDEs. The Infant-Toddler Social and Emotional Assessment (ITSEA) was completed by mothers when children were approximately 30 months of age (n = 222). We assessed the relationship between breast milk concentrations of five PBDE congeners-BDEs 28, 47, 99, 100, and 153-and children's social and emotional development, adjusting for other factors.

RESULTS: A small, imprecise, yet consistent positive association was apparent between BDEs 47, 99, and 100 and increased externalizing behaviors, specifically activity/impulsivity behaviors. Externalizing domain T-scores ranged from 30 to 87 with a mean of 47.8. Compared with those with BDE-47 concentrations below the median, adjusted externalizing behavior domain scores were 1.6 [95% confidence interval (CI): -1.2, 4.4] and 2.8 (95% CI -0.1, 5.7) points higher for children born to women with breast milk concentrations in the 3rd and 4th quartiles, respectively. PBDEs were not associated with other social and emotional developmental domains.

CONCLUSIONS: Our results, although imprecise, suggest a subtle association between early-life PBDE exposure and increased activity/impulsivity behaviors in early childhood. Confirmation of these results is needed in other longitudinal studies.