A study released today reveals human exposure to the worrisome chemical bisphenol a (BPA) is much higher than some previous estimates and likely comes from many -- and still unknown -- sources.
The study, published in the Environmental Health Perspectives online journal, also reveals that data on the effects of BPA in rodents and primates are relevant to what researchers call human heath predictions.
The study examined the effects of BPA -- given orally in the same controlled doses -- to adult female rhesus macaques and adult female mice.
Researchers at the University of Missouri and the Washington State University then compared those findings to previously published data regarding BPA exposure in women.
In the study titled: Similarity of Bisphenol A Pharmacokinetics in Rhesus Monkeys and Mice: Relevance for Human Exposure researchers found what they consider major similarities in the way BPA is metabolized in women, female monkeys, and female mice. Those findings are important because they indicate that studies regarding the effects of BPA in rodents and primates are useful to regulatory agencies interpreting animal data on the safety of BPA exposure in humans.
Researchers made another grave finding in their study of the BPA, a controversial and widely-used industrial chemical found in baby bottles, sport drink containers, medical equipment, some dental sealants, and the liners in metal food cans and water supply pipes.
They found humans daily exposure to the endocrine disrupting chemical linked to heart disease, developmental problems, diabetes, obesity, and reproductive issues is much higher -- and from more sources -- than the Food and Drug Administration (FDA) and other governmental agencies previously suspected.
Our data raise grave concern that regulatory agencies have grossly underestimated current human exposure levels, the study states. On this basis of our findings, we propose that the higher than predicted serum levels of unconjugated BPA in men and women reflect significant non-oral BPA exposure in addition to oral exposure.
This is consistent with other evidence suggesting that the consumption of BPA contaminated food and beverages alone is insufficient to account for the BPA levels reported in human biomonitoring studies, the study added.
Some of the non-oral ways people are exposed to BPA is through their skin, researchers said. One example of a recently identified source of human exposure to BPA is thermal (carbonless) paper receipts that could potentially result in trans-dermal exposure, the study states.
Childrens books and cigarette filters are other newly recognized routes of BPA exposure in humans. There is significant leaching of BPA from childrens books and BPA is also present in cigarette filters, raising the concern that inhalation of cigarette smoke may be another previously unrecognized source of exposure for individuals who smoke, the study found.
Safety questioned
But why should people care about their exposures to BPA? One reason, scientists say, is because the safety of the chemical remains under fire.
Some organizations say the chemical poses little to no risk to humans. But a large body of evidence links BPA to various health issues in humans and animals, the study noted.
Earlier this year, the FDA stated the agency has some concerns about the potential effects of BPA on the brain, behavior, and prostate gland in fetuses, infants, and young children.
The authors of this latest study urged regulators to identify all products that contain BPA.
Although much remains to be determined about the mechanisms of action of BPA, which varies depending upon the dose, tissue and the life stage of exposure, understanding the current levels of human exposure and the various routes of exposure to BPA, how BPA is metabolized, and whether animal models are relevant for modeling human exposure is critical to better understand the risk posed to humans, the study states. The urgent need for this information is underscored by the CDCs conclusion that over 90% of people in the USA are chronically exposed to BPA and the suggestion that this likely also applies to people living in other countries around the world.
The study added: Surprisingly, there are no data that directly bear on the question regarding sources and amounts of human exposure to BPA, and estimates of current daily BPA exposure levels vary widely.
ConsumerAffairs.com contacted a trade group for chemical makers about todays study. A spokesman for the American Chemistry Council (ACC) reiterated the organizations position that BPA does not pose harm to humans.
Consistent with previously published studies, including comprehensive studies by FDA researchers, this new study confirms that BPA is efficiently metabolized and rapidly eliminated from the body after oral exposure, the organizations Steven G. Hentges, Ph.D., said in a written statement.
The study also confirms that BPA does not bioaccumulate in the body. Although this new study did not measure human exposure to BPA, it does validate the findings from recent large-scale biomonitoring studies conducted by the US CDC (Centers for Disease Control and Prevention) and Health Canada. Both of these studies indicate that typical human exposure to BPA, from all sources, is 1,000 times or more lower than the safe intake limits set by government bodies around the world.
He added: Overall, this new study continues to support the conclusions of government bodies around the world that BPA does not pose a risk at the very low levels to which people might be exposed.
What to do?
But what about consumers who remain worried about their exposure to this hotly-debated chemical? What steps can they take to reduce their exposure to BPA?
The National Institute of Environmental Health Studies recommends the following:
• Use BPA-free baby bottles;
• Dont microwave food containers made with polycarbonate plastic. Polycarbonate may break down from over-use at high temperatures;
• Reduce the use of canned foods;
• Use food containers made of glass, porcelain, or stainless steel whenever possible, especially for hot foods and liquids;
• Avoid buying plastic products made with BPA. Those products may have the recycling number 7 on the bottom.
BPA Exposure Much Higher Than Previously Thought, Study Finds...