April 15, 2008 -- Government scientists today weighed in on possible health risks linked to the plastic chemical bisphenol A -- and in some cases, they note higher risk than their advisory panel.
That news comes amid media reports that Canada's government may soon classify bisphenol A as a dangerous substance. The chemical, found in polycarbonate plastic, is used in a range of food containers, from baby and water bottles to the resins that line metal food cans.
Today's U.S. report doesn't go that far; it doesn't make any recommendations about bisphenol A. What the report does say is that government scientists have "some" concern about bisphenol A's effects, while a previous report voiced "minimal" concern about those potential effects.
"We're certainly not out to alarm people," Michael D. Shelby, PhD, director of the National Toxicology Program's Center for the Evaluation of Risk to Human Reproduction, tells WebMD.
"If people are concerned about it, there are ways they can reduce their exposure to bisphenol A, and if they feel it's necessary they should take those steps," says Shelby, who headed the group of government scientists that issued today's draft report.
What the Report Found
Today, the NTP posted a draft of its own report on bisphenol A. It based its findings in part on research conducted by an expert panel for the NTP that was published last year along with new scientific research published since the expert panel did its work, and public comments on the expert panel's review.
Shelby says while they largely agreed with the expert panel, which was convened by the Center for the Evaluation of Risk to Human Reproduction, they broadened the areas they felt could be of "some" concern, including effects on the mammary gland, prostate gland, and acceleration of puberty in females.
Both groups agreed that there already was some concern that exposure to the chemical could cause neural and behavioral effects in fetuses, infants, and children.
The evidence -- which came from studies on rodents, not people -- was "very limited," Shelby says. "But our conclusion was that we couldn't dismiss the possibility that similar effects might occur in humans."
"This is a very controversial area with obvious differences in the way different groups have interpreted the data," Shelby says. "We have tried to do it in as scientifically sound and thorough means as we could."
"Even in the areas where we've expressed some concern, the literature is not consistent on the endpoints reported," Shelby continues. "Some people find these effects; others may not, and their relevance to effects on human health -- there's still some uncertainty about that. That's why we didn't have a lower or higher level of concern in our conclusions."
The draft brief is posted on the NTP's web site. The NTP is taking comments on the brief, which will be reviewed by other scientists in June.
Shelby expects to issue the final version of the NTP's brief on bisphenol A in late summer. But that report won't include any rules on BPA's use. "We are not a regulatory agency," Shelby says.
In a statement emailed to WebMD, the American Chemistry Council says the NTP's draft brief "confirms that human exposure to bisphenol A is extremely low and noted no direct evidence in humans that exposure to bisphenol A adversely affects reproduction or development."
Limited evidence for effects in lab animals "primarily highlights opportunities for additional research to better understand whether these findings are of any significance to human health," states the council.
"The findings in NTP's draft report provide reassurance that consumers can continue to use products made from bisphenol A," says Steven Hentges, PhD, of the American Chemistry Council's Polycarbonate/BPA Global Group. "Importantly, this conclusion has been affirmed by scientific and government bodies worldwide."
Tips for Limiting Exposure to BPA
The National Institute of Environmental Health Sciences, which includes the NTP, has posted the following tips on its web site for people who want to limit their exposure to bisphenol A:
- Don't microwave polycarbonate plastic food containers. Polycarbonate is strong and durable, but over time it may break down from overuse at high temperatures.
- Polycarbonate containers that contain BPA usually have a #7 on the bottom.
- Reduce your use of canned foods.
- When possible, opt for glass, porcelain, or stainless steel containers, particularly for hot foods or liquids.
- Use baby bottles that are BPA-free.