New scientific findings published on May 27, 2015 in the peer-reviewed journal Environmental Health Perspectives show for the first time that conjugated, “detoxified” bisphenol A (BPA, CAS 80-05-7) is indeed biologically active (Boucher et al. 2015). These results stand in contrast to the assumption that glucuronidated BPA (BPA-G), the body’s detoxification product of BPA, is safe due to its alleged biological inactivity.
Researchers from Health Canada, a government institution, tested the ability of BPA-G to induce lipid accumulation in 3T3L1 cells, a mouse cell culture that can differentiate into fat cells (or: adipocytes) under appropriate conditions. Furthermore, also primary human preadipocytes were used (cells came from healthy donors). Both types of cells responded to BPA-G exposure in a dose- and time-dependent way, indicating that treatment with the conjugated chemical caused cells to differentiate into adipocytes. Interestingly, the effect was inhibited in the presence of an estrogen receptor (ER) blocker; previous studies have shown that BPA-G is not estrogenic.
The authors conclude that “BPA-G is biologically active and promotes adipocyte differentiation and lipid accumulation in vitro.” Further, they state that “while BPA-G does not have estrogenic-activity, BPA-G induced adipogenesis is still inhibited by an ER antagonist, suggesting that it may be acting through non-classical ER action or as yet unidentified pathway.”
In previous risk assessments of BPA the conjugated BPA-G has been assumed to be biologically inactive and therefore not of health concern. Most recently in January 2015, the European Food Safety Authority published its Scientific Opinion on BPA (FPF reported), stating that BPA-G is “of less toxicological concern if at all”.
Boucher, J.G. et al. (2015). “In vitro effects of bisphenol A β-D-glucuronide (BPA-G) on adipogenesis in human and murine preadipocytes.” Environmental Health Perspectives (published online May 27, 2015, open access).
Brian Bienkowski (May 29, 2015). “Do our bodies safely break down BPA? Fat chance, study suggests.” Environmental Health News
North American Metal Packaging Alliance (May 28, 2015). “BPA Study Report Card.” (pdf)