—More Concerns Over Bisphenol A “Human exposures are usually as high as those causing profound effects in rodents” THE SUSPECTED LINK between low levels of human exposure to bisphenol A (BPA), a monomer widely used to make polycarbonate plastic and epoxy resins, and adverse health affects was bolstered last week with the publication of four toxicology studies that investigated the link. The most significant paper is a consensus statement from 38 scientists released online in Reproductive Toxicology (DOI: 10.1016/j.reprotox.2007.07.005). It concludes that human exposure to BPA, primarily from food containers, is within the range shown to be biologically active in animal studies. In rodents, low BPA exposures in the womb cause increases in the rates of prostate and breast cancer, reproductive abnormalities, lowered sperm counts, early onset of puberty in females, and obesity and insulin-resistant diabetes. A second paper in Reproductive Toxicology echoes those conclusions (DOI: 10.1016/j.reprotox.2007.07.010). It compiles an array of published data on BPA's effects and concludes that BPA levels in human tissues are higher than levels sufficient to cause adverse effects in lab animals. The analysis reports that many people are exposed to more than 50 µg per kg of body weight per day, the safety threshold set by EPA in 1984. A third Reproductive Toxicology paper found that when BPA is administered to newborn female mice for five days, they develop ovarian cysts and uterine abnormalities (DOI: 10.1016/j.reprotox.2007.07.006). The fourth study, published in the Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0703739104) finds that exposure to BPA in the womb alters the coat colors of genetically identical agouti mice.
by Bette Hileman |
August 06, 2007