Maternal serum polybrominated diphenyl ether concentrations during pregnancy and adolescent bone mineral density at age 12 years

Polybrominated diphenyl ethers (PBDEs), used as chemical flame retardants, are developmental osteotoxicants in mechanistic studies, but the effects of in utero exposure on adolescent bone health are unknown. We examined associations of gestational serum PBDE concentrations and BMD Z-scores in adolescence. Among 184 mother-adolescent pairs enrolled in the Health Outcomes and Measures of the Environment Study (Cincinnati, OH: 2003-2006), we quantified five PBDEs in maternal serum and four organophosphate ester (OPE) metabolites in maternal urine collected at 16- or 26-weeks gestation. At age 12 years, we conducted dual energy x-ray absorptiometry scans and calculated bone mineral density (BMD) Z-scores for six skeletal sites. We estimated covariate-adjusted associations per log₁₀ increase in maternal serum PBDE concentrations using linear regression and assessed effect measure modification (EMM) by adolescent's sex using interaction terms. We also examined PBDE and OPE mixtures using quantile-based g-computation. In adjusted models, BDE-153 concentrations were associated with lower femoral neck BMD (β: -0.42; 95 % CI: -0.79, -0.05). Results were similar but weaker for other individual PBDEs and their mixture. The associations of BDEs-28, -47, and -100 with hip and femoral neck BMD Z-score were modified by adolescent's sex. For example, log₁₀ BDE-28 was associated with total hip BMD Z-score differences of -0.75 (95 % CI: -1.50, 0.01) for males and 0.21 (95 % CI: -0.31, 0.74) for females (EMM p = 0.04). Higher quartiles of the PBDE + OPE mixture showed weak, site-specific associations with BMD, though all CIs crossed the null. In utero PBDE exposure may negatively affect adolescent bone health.