Derivation of an oral Maximum Allowable Dose Level for Bisphenol A

Bisphenol A (BPA) is a high production volume chemical that is used in plastics and epoxy coatings. In 2015, California's Office of Environmental Health Hazard Assessment (OEHHA) added BPA to the Proposition 65 list of chemicals “known to cause reproductive toxicity” based on its Developmental and Reproductive Toxicant Identification Committee's (DART-IC) conclusion that BPA has been shown to cause female reproductive toxicity. A critical factor in determining compliance with Proposition 65 is a Maximum Allowable Dose Level (MADL), which is the exposure level at which a chemical would have no observable reproductive effect even if a person were exposed to 1000 times that level. We performed a comprehensive review of the literature, including the studies reviewed by DART-IC, and derived an oral MADL. Of all the studies we identified, Delclos et al. (2014) is of sufficient quality, has the lowest no observed effect level (NOEL), and results in the most conservative MADL of 157 μg/d. This is generally supported by other studies, including those that were considered by DART-IC. Also, the oral MADL provides a similar margin of safety as OEHHA's dermal MADL and other regulatory guidelines. Taken together, the scientific data support an oral MADL of 157 μg/d.