Scientific Battle Brewing over BPA Safety
The Independent has reported on an escalating dispute in the scientific community over the safety of bisphenol A (BPA), tracing the brouhaha to a three-year study commissioned by the Environmental Protection Agency (EPA) that found no evidence of BPA adversely affecting laboratory rats exposed to high doses of the ubiquitous plasticizer. In an April 13, 2010, article, science editor Steve Connor observes that Toxicological Sciences, which published the original work online in 2009, has become the battleground of choice for scientists arguing the merits of the research. Additional details about the EPA study appear in issue 327 of this Update.
According to The Independent, University of Missouri-Columbia Professor Frederick vom Saal first attacked the results in a letter to the journal, claiming that EPA researchers “violated U.S. National Toxicology Program recommendations” by failing to establish “the sensitivity of the animal model to the class of chemical being tested.” This allegation, however, immediately drew fire from Professor Richard Sharpe of the U.K. Medical Research Council’s Center for Reproductive Biology. In the March edition of Toxicological Sciences, Sharpe defended the EPA findings as “unequivocal and robust.” He also lambasted the scientific community at large for wasting “tens, probably hundreds of millions of dollars” by refusing to revise its initial opinion on BPA even after secondary studies have consistently found in favor of its safety. As Sharpe concluded, “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.”
Meanwhile, lead study author Earl Gray has publicly described his methodology as the one recommended by regulatory agencies for testing potentially toxic substances. His team has drafted a rebuttal that was recently accepted by Toxicological Sciences for future publication and highlighted in the April 7 edition of STATS, a George Mason University blog, which has questioned whether BPA is destined to become the “new MMR” (the controversial measles, mumps and rubella vaccine). Both STATS and The Independent quote Gray as maintaining that the “‘insensitive rat’ argument has been used for almost a decade in some quarters to try to dismiss every well-conducted rat study that obtained negative results with BPA.”
