You may have seen water bottles labeled “BPA Free” or heard that certain foods contain BPA. BPA (or bisphenol A) has been in the news over the past several years. BPA is weakly estrogenic; that is, BPA may mimic some of the hormone-like effects of estrogen. BPA is used primarily in making polycarbonate plastic and some epoxy resins. The general population is exposed to BPA mainly through diet.

A lot of attention has been paid to genetics in breast cancer as disease rates rise, but most women have no family history of the disease, suggesting that there is an environmental risk we don’t yet understand, says environmental health scientist Laura Vandenberg in the School of Public Health and Health Sciences at the University of Massachusetts Amherst.