Prospective Evidence: BPA, Phthalates, and Type 2 Diabetes

Sarah Howard
Coordinator of CHE’s Diabetes and Obesity Spectrum Working Group

The first prospective study on diabetes in relation to BPA or phthalates has just been published (ahead of print), in Environmental Health Perspectives. The results suggest that BPA and phthalate exposures may be associated with the risk of type 2 diabetes among middle-aged women, but not older women. The association between BPA and phthalates in younger but not older women may be due to menopausal status (although chance cannot be ruled out).

The study analyzed levels of BPA and eight phthalates in two urine samples over 1-3 years from U.S. women in the Nurses’ Health Study I (average age 66) and II (average age 46). The younger women had higher levels of BPA and phthalates than the older women, yet these differences did not explain the findings.

Because experimental data suggests that BPA interferes with the function of the insulin-producing pancreatic beta cells by activating estrogen receptors, the authors hypothesized that any associations between BPA and diabetes would be stronger in pre-menopausal women than post-menopausal women. Indeed, the association between BPA and diabetes shows a clear linear trend in pre-menopausal women, but there is no association in post-menopausal women. And, the association between BPA and diabetes was stronger in women who developed diabetes at a younger age (under 55). These interesting findings should be examined in other cohorts.

Sun Q, Cornelis MC, Townsend MK, Tobias DK, Eliassen AH, Franke AA, Hauser R, Hu FB. 2014. Association of Urinary Concentrations of Bisphenol A and Phthalate Metabolites with Risk of Type 2 Diabetes: A Prospective Investigation in the Nurses’ Health Study (NHS) and NHSII Cohorts. Environ.Health Perspect. http://ehp.niehs.nih.gov/1307201/