Experts Doubt Bisphenol A Risky for Humans
A commentary published this month in Toxicological Sciences, the Society of Toxicology's journal, says the latest research "closes the door" on claims the chemical is an environmental hazard of concern.
The Society of Toxicology's members and leaders are starting their 49th Annual Meeting today at Salt Lake City's Salt Palace Convention Center, with dozens of sessions taking place about topics of current concern, such as limiting animal testing, lessons learned from the NIEHS Superfund Research Program, and progress to date of a collaboration formed in 2008 to improve the safety testing of chemicals. Live updates from the March 7-11 event will be provided on the Web sites of NIENS (the National Institute of Environmental Health Sciences) and the National Toxicology Program.
Meanwhile, a paper and commentary published this month in Toxicological Sciences, the society's journal, say the newest research indicates Bisphenol A does not adversely affect reproductive development, function, or behavior in female rats, suggesting the chemical is not an environmental hazard to human beings. Richard M. Sharpe ([email protected]) of the Medical Research Council Human Reproductive Sciences Unit, Centre for Reproductive Biology at The Queen's Medical Research Institute in Edinburgh, Scotland, wrote the commentary titled "Is It Time to End Concerns over the Estrogenic Effects of Bisphenol A?" and the paper is "In Utero and Lactational Exposure to Bisphenol A, In Contrast to Ethinyl Estradiol, Does Not Alter Sexually Dimorphic Behavior, Puberty, Fertility, and Anatomy of Female LE Rats," written by Bryce C. Ryan, Andrew K. Hotchkiss, Kevin M. Crofton, and L. Earl Gray, Jr.
"The results from Ryan et al. (2009) are unequivocal and robust and are based on a valid and rational scientific foundation. They tell us that, in vivo in female rats, bisphenol A is an extremely weak estrogen—so weak that even at levels of exposure 4000-fold higher than the maximum exposure of humans in the general population there are no discernible adverse effects, whereas the potent estrogen ethinyl estradiol (EE; the positive control) caused major adverse effects at doses used in earlier contraceptive pills and that were associated with increased risk of thromboembolism," Sharpe wrote. His commentary's concluding paragraph starts with this: "Fundamental, repetitive work on bisphenol A has sucked in tens, probably hundreds, of millions of dollars from government bodies and industry which, at a time when research money is thin on the ground, looks increasingly like an investment with a nil return. All it has done is to show that there is a huge price to pay when initial studies are adhered to as being correct when the second phase of scientific peer review, namely, the inability of other laboratories to repeat the initial studies, says otherwise."
In January 2010, the U.S. Food and Drug Administration summarized its stance on Bisphenol A by saying that it "shares the perspective of the National Toxicology Program that recent studies provide reason for some concern about the potential effects of BPA on the brain, behavior, and prostate gland of fetuses, infants and children." FDA also said it "recognizes substantial uncertainties with respect to the overall interpretation of these studies and their potential implications for human health effects of BPA exposure. These uncertainties relate to issues such as the routes of exposure employed, the lack of consistency among some of the measured endpoints or results between studies, the relevance of some animal models to human health, differences in the metabolism (and detoxification) of and responses to BPA both at different ages and in different species, and limited or absent dose response information for some studies," and the agency said it is conducting more studies.