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.