The main conclusions of the NTP report include expression of ‘some concern’ over the potential for developmental toxicity for foetuses, infants, and children, based primarily on evidence from animal studies that would suggest that there might be effects on prostate gland and brain development, with also the potential for behavioural effects.
The NTP, an interagency programme of the US Department of Health and Human Services, also noted ‘minimal concern’ over potential for changes in mammary gland development and early female puberty – which is a lower level assessment from the ‘some concern’ evaluation it issued in its draft report on BPA in April.
"Some concern" is in the middle part of a five-level concern scale the NTP uses that ranges from "negligible concern" to "serious concern".
The NTP said its report is the result of a comprehensive and rigorous scientific review process that included an earlier report from a panel of independent scientific experts, public comments received on the report, peer review comments, and new relevant scientific literature.
Migration
According to the NTP, BPA in food and beverages accounts for the majority of daily human exposure.
The chemical is used in certain packaging materials such as polycarbonates for water bottles, drinks and baby food bottles. It is also used in epoxy resins for internal protective linings for canned food and metal lids.
Concerns have arisen over BPA since it has been found to migrate in small amounts into foods and beverages stored in the materials and some recent animal studies indicated that high levels of BPA could be carcinogenic.
The NTP said that the degree to which BPA leaches from polycarbonate bottles into liquid may depend more on the temperature of the liquid or bottle, than the age of the container.
In December 2007, Canadian retailer, Mountain Equipment Co-op, decided to stop selling sales of Nalgene bottles made of BPA, while the US retailer Wal-Mart recently announced that it will phase out bottles containing BPA by 2009.
Additional studies urged
The NTP noted limited and inconclusive evidence from animal studies that could indicate health concerns but it said that further research will be needed to determine if these concerns are relevant to human health.
“There are insufficient data from studies in humans to reach a conclusion on reproductive or developmental hazards presented by current exposures to bisphenol A, but there is limited evidence of developmental changes occurring in some animal studies at doses that are experienced by humans.
“It is uncertain if similar changes would occur in humans, but the possibility of adverse health effects cannot be dismissed,” claims the agency.
“The fact that there are so many levels of uncertainty makes it very difficult for us to make any kind of overall recommendations as to how exactly the US public should view BPA right at this point,” said John R. Bucher, NTP associate director.
He said that the report indicates a number of research areas that the NTP believes need following up on to reduce the uncertainties and “allow a clearer picture of exactly what we should be doing as a society with regards to exposures to BPA”.
FDA
The NTP has no power to regulate BPA, but its findings are used by other federal agencies such as the Food and Drug Administration (FDA) and the Environmental Protection Agency, which set safe exposure limits for chemicals.
An FDA draft report, however, released last month found that BPA is safe at current human exposure levels. This was in line with the report issued in July by the European Food Safety Agency (EFSA), which said that the human body rapidly metabolises and eliminates the substance and thus BPA presents no risk to adults, children or infants.
The FDA Subcommittee on BPA announced that it will hold a public meeting in relation to its draft assessment on September 16 in Washington.
Chairman of the US House of Representatives’ Committee on Energy and Commerce, John D. Dingell, said yesterday that the FDA is relying on industry based research to arrive at its conclusions rather than examining the totality of scientific evidence.
The Committee is examining the FDA’s review of the chemical.
New research
Meanwhile, according to a report in today’s Washington Post, a group of Yale researchers, in a study published in the Proceedings of the National Academy of Sciences, found that monkeys exposed to levels of BPA considered safe for humans by the EPA had interference with brain cell connections vital to memory, learning and mood.
"Our findings suggest that exposure to low-dose BPA may have widespread effects on brain structure and function," claim the researchers.
The Yale team said that they studied monkeys to better approximate the way BPA might affect humans.
Industry perspective
The American Chemistry Council (ACC) maintains that bisphenol A is safe at current exposure levels.
"The safety of our products is our highest priority," claims Steven G. Hentges, of the ACC’s Polycarbonate/BPA Group.
He welcomed the NTP findings which he said “identified no serious human health concerns” and “will provide important input into safety assessments of consumer products containing bisphenol A.”