Bisphenol A (BPA) is an industrial chemical found in polycarbonate plastics, epoxy resins, dental sealants and thermal paper used in receipts and other substances. BPA is one of the highest volume chemicals produced worldwide and is found pervasively in the environment worldwide.
Human exposure to BPA occurs primarily through food consumption and through skin contact with thermal paper. Over the past 10 to 15 years there has been high concern about the health effects of BPA, although it has been known to be an endocrine disrupting chemical since 1936.
BPA can act as an endocrine disrupting chemical by binding to estrogen receptors and androgen receptors to have both agonistic and antagonistic effects on estrogen production, as well as through nonclassical estrogen pathways. Exposure to BPA has been associated with significantly increased mammographic density — a known risk factor for breast cancer — in postmenopausal women as well as increased mammary growth and lesions in rodents.