Dietary exposure to brominated flame retardants and risk of type 2 diabetes in the French E3N cohort

Introduction: The prevalence of type 2 diabetes (T2D) is increasing worldwide. Recent studies have suggested that environmental factors, such as exposure to brominated flame retardants (BFRs), could play a role in the epidemic of T2D. The aim of this study was to analyze the association between the dietary exposure to BFRs (Hexabromocyclododecane (HBCD) and Polybromodiphenylether (PBDE)) and T2D risk in the E3N prospective cohort of French women. Research design and methods: Overall, 71,415 women followed for 19 years were included in the study. We performed Cox regression models to analyze the association between dietary exposure to BFRs and T2D risk. Results: Overall 71,415 women were included and 3667 (5.13%) developed a T2D during follow-up. The mean dietary exposure to HBCD and to PBDE was 0.22 ng/kg body weight (BW)/day and 1.21 ng/kg bw/day, respectively. There was a positive linear association between dietary exposure to HBCD and T2D risk starting from the 2nd quintile group (HR: 1.18; 95% CI: 1.06–1.30) to the 5th quintile group (HR: 1.47; 95% CI: 1.29–1.67) when compared to the 1st quintile group. We also found positive although non-linear associations between dietary exposure to PBDE and T2D risk, with an increased HR only for the 2nd and 4th vs. 1st quintile groups (HR: 1.12; 95% CI: 1.02–1.24, and HR: 1.20; 95% CI: 1.08–1.34, respectively). Conclusion: The findings suggest an association between dietary exposure to BFRs and T2D risk, highlighting the importance of further investigating this association the long-term health effects of endocrine disruptors in the general population. Additional studies are needed to reproduce these findings in other populations and clarify the underlying biological mechanisms.