Human Exposure to Brominated Flame Retardants and Reproductive Health.

Abstract

Brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and other compounds are used in the manufacture of a variety of materials and consumer products to meet fire safety standards. BFRs persist in the environment and have been detected in wildlife, humans and indoor dust and air. Some BFRs have demonstrated adverse endocrine and reproductive effects, but human studies are limited. We investigated markers of exposure to BFRs using serum, ovarian follicular fluid and house dust collected from men and women attending infertility clinics. House dust concentrations of the major pentaBDE commercial formulation congeners (BDE 47, 99 and 100) were highly correlated (r=0.65-0.89) to serum concentrations of the same congeners, suggesting that dust is a major exposure source of these PBDEs. Serum concentrations of these congeners were also strongly correlated (r=0.85) between males and females, indicating that adults living in the same household have similar exposures. PBDE congeners in dust were grouped into penta-, octa- and deca-BDEs, resembling commercial mixtures, and alterations in hormone levels in men were modeled in relation to PBDE exposure. Significant positive associations (p<0.05) were found between dust concentrations of pentaBDEs and serum levels of thyroid hormones T4 and T3, estradiol, sex hormone binding globulin (SHBG) and prolactin, along with an inverse association with follicle stimulating hormone. Positive associations between octaBDE concentrations and serum T4, thyroid stimulating hormone, luteinizing hormone and testosterone, and an inverse association between decaBDE concentrations and testosterone, were also found. Relationships between alternate BFRs and hormone levels were examined. Hexabromocyclododecane was associated with decreased SHBG and increased free androgen index. The association between serum and follicular fluid concentrations of PBDEs and failed embryo implantation was investigated. Women with detectable levels of BDE 153 in follicular fluid had elevated odds (adjusted OR=10.0, 95%CI: 1.9-52) of failed embryo implantation following in vitro fertilization (IVF), compared with women who had non-detectable concentrations. There was only a moderate correlation (T<0.4) between serum and follicular fluid concentrations of PBDEs; therefore follicular fluid PBDEs, which may be a more biologically relevant measure of exposure when studying IVF endpoints, may not be well-estimated by serum concentrations of PBDEs.