US panel has 'some concern' about effects of bisphenol A
Worries over neural effects in children, but reassurances on other risks.
A US government-appointed scientific panel has said it has "some concern" that a compound found in many plastics may cause neural and behavioural abnormalities in infants and children at concentrations normally found in humans. But the panel found negligible concern that those exposed to typical levels of the compound, called bisphenol A, would develop reproductive problems or birth defects.
The panel, which announced its findings on Wednesday 8 August, was convened by a division of the National Institute of Environmental Health Sciences (NIEHS) called the Center for the Evaluation of Risks to Human Reproduction (CERHR). Its report will now undergo review by the US National Toxicology Program and there will be two additional public comment periods before it is finalized. At that point it could serve as the basis for subsequent regulation of bisphenol A.
The findings stand in stark contrast to the conclusions of an independent scientific panel assembled by Jerrold Heindel, a scientist who is also at the NIEHS. That panel published a consensus statement a week ago, citing its conclusion that prenatal or neonatal bisphenol A exposure alters the prostate, breasts, testes, mammary glands, body size, and behaviour later in life. The consensus statement was published along with two new bisphenol A studies to appear in the journal Reproductive Toxicology1,2, but the reports came too late for consideration by the CERHR panel, says its chair, Robert Chapin of Pfizer.
"We have two different efforts with different but complementary approaches," says Heindel, who adds that he expects conclusions from both his panel and the CERHR panel to be incorporated in the final Institute report.
Members of the CERHR panel stopped short of advising the public to avoid bisphenol A, which is found in some plastic food containers and baby bottles and is sometimes used as a coating in food cans. Michael Shelby, director of the CERHR, said that he would continue to respond to queries from concerned consumers as he had been before. "The science cannot definitively give them an answer about what effect those exposures might have," Shelby said. "If they are concerned about those exposures, then there are alternatives."
Exclusions and accusations
The CERHR panel reviewed over seven hundred published studies, but excluded many that they did not find scientifically convincing from their final analysis. For example, the panel criticized rodent studies that administered bisphenol A via injection, rather than orally, saying that these studies did not accurately reflect human exposure to the compound.
But Frederick vom Saal, a biologist at the University of Missouri, Columbia, and an author of the consensus statement published the previous week, says that such studies are useful and should be considered.
Levels of concern expressed by the CERHR panel were also based upon estimations of typical human exposure drawn from previous literature, and the panel noted that highly exposed groups of people, such as those who work with bisphenol A, may be at a higher risk.
The CERHR panel was also beset with conflict-of-interest accusations last spring, when it was found that the panel hired a consulting company with industry ties (see 'Regulators pull contract for chemical review'). That company was dismissed in March, and the US National Toxicology Program launched an audit of its performance. That audit found that six of more than 300 changes suggested by panel members via email were not incorporated into the draft report, and an additional 50 papers that were deemed potentially relevant to panel deliberations were also not represented. The CERHR says that the suggested changes and missing references identified in the audit were passed on to the committee and were considered in creation of the final report.
"There did not appear to be any systematic bias," says Chapin. "I have zero concern about that."
- Vandenberg, N. et al. Rep. Tox., doi:10.1016/j.reprotox.2007.07.010 (2007).
- Newbold, R. et al. Rep. Tox., doi:10.1016/j.reprotox.2007.07.006 (2007).
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