Prenatal Polybrominated Diphenyl Ether (PBDE) Exposure and Social Cognition at Age 14

Background: An accumulating body of literature has linked prenatal exposure to polybrominated diphenyl ethers (PBDEs), chemicals used as flame retardants in furniture, electronics, textiles and other consumer products, to behavior problems in childhood, suggesting that PBDEs may act as developmental neurotoxicants in humans. Epidemiologic findings to date on PBDE exposure and autism spectrum disorder (ASD) are very limited. In the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study, a birth cohort of predominantly Mexican-Americans in an agricultural region of California, prenatal PBDE exposure was associated with poorer attention, fine motor coordination, and cognition at ages 5-7 and poorer attention and executive function at ages 9-12.

Objectives: To examine the influence of prenatal exposure to PBDEs on social cognition, a trait impaired in individuals with ASD, in early adolescence.

Methods: We measured concentrations of 4 common PBDE congeners (BDE-47, 99, 100, 153) in blood contributed by CHAMACOS mothers during the second half of pregnancy (in 2000-2002). When children were aged 14 years, parents completed the Social Responsiveness Scale, Second Edition (SRS-2), a rating scale of traits related to ASD. Using generalized additive models, we examined associations of serum lipid-adjusted PBDE concentrations in relation to sex-standardized SRS-2 T-scores (population standard mean=50, standard deviation=10), with adjustment for child’s age at SRS-2, breastfeeding duration, household income, maternal characteristics (age, parity, education, country of origin, years in the United States, pre-pregnancy body mass index, and IQ), and measures of maternal depression and support for cognitive development in the home.

Results: 147 children with SRS-2 scores, prenatal PBDE measures, and relevant covariates were included. Median (25%─75%) serum lipid-adjusted PBDE concentrations were: 15.0 ng/g lipid (8.7─24.5) [BDE-47], 3.7 (2.4─6.9) [BDE-99], 2.4 (1.6─4.2) [BDE-100], 2.0 (1.4─3.6) [BDE-153]. SRS-2 T-scores ranged from 41─88 with a mean (standard deviation) of 55.3 (7.8). Relationships of SRS-2 T-scores with log10-tranformed PBDE concentrations appeared linear, and scores were higher (representing more autistic behaviors) among children whose mothers had higher concentrations of BDE-153 in pregnancy (β=3.5; 95% confidence interval (CI): -0.5, 7.5 per 10-fold increase in maternal BDE-153 concentration). SRS-2 scores did not appear associated with the other measured PBDE congeners or the sum of the four PBDE congeners (β=0.7; 95% CI: -3.0, 4.4).

Conclusions: Among young adolescents living in a low-income agricultural community, behaviors related to ASD appeared somewhat elevated in those with higher prenatal exposure to BDE-153, but not other measured PBDEs. BDE-153 is a component of the commercial flame retardants penta- and octabromodiphenyl ethers (penta- and octaBDEs), which were phased out of production in the United States in 2004 due to concerns about potential toxicity, but remain present in older consumer products.