The association between brominated flame retardants exposure with bone mineral density in US adults: A cross-sectional study of the national health and nutrition examination survey (NHANES) 2005–2014

Exposure to brominated flame retardants (BFRs) has been widely confirmed to impair the normal functioning of the human body system. However, there is a paucity of study on the effects of serum BFRs on bone mineral density (BMD). This study aims to investigate the relationship between exposure to BFRs and BMD in a nationally representative sample of U.S. adults. 3079 participants aged between 20 and 80 years with complete data were included in the study. Serum levels of BFRs were measured using automated liquid-liquid extraction and subsequent sample clean-up. The BMD of all participants were assessed by DXA examinations. Generalize linear model, Restricted cubic spline (RCS), subgroup, weighted quantile sum (WQS) and bayesian kernel machine regression (BKMR) were used to estimate the association between serum BFRs and BMD. Multivariate linear regression analyses revealed that, after adjusting for covariates, PBB153 was significantly associated with TF-BMD (β = 0.0177, 95%CI: 0.0103–0.0252), FN-BMD (β = 0.009, 95%CI: 0.0036–0.0145), TS-BMD (β = 0.0081, 95%CI: 0.0013–0.015) and L1-BMD (β = 0.0144, 95%CI: 0.0075–0.0213). However, the associations lose their statistical significance after further adjustment for sex. BFRs exhibited S-shaped or line-plateau dose-response curves with BMD. In subgroup analyses, BFRs were significantly associated with BMD in participants who were younger than 55 years, female, overweight (BMI >25 kg/m2), and less alcohol consumption. In WQS and BKMR analyses, the effects of BFRs mixtures on BMD differed by sex, and PBDE153, PBDE209 and PBB153 had the highest weights in the WQS regression model. This study showed that serum BFRs negatively predicted BMD in men, but not in women or the general population. PBDE153, PBDE209, and PBB153 were significant BMD factors, especially in younger, overweight, and less alcohol consumption individuals.