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Bisphenol A, what is it about?

Fahmi Rizwansyah says:

By Miranda Hitti
WebMD Feature
Reviewed by Louise Chang, MD

What is bisphenol A?
Bisphenol A, also called BPA, is a chemical found in polycarbonate plastic and epoxy resins.

Polycarbonate plastics are used in certain food and drink packaging (including some water bottles and baby bottles) and also in compact discs, computers, impact-resistant safety equipment (such as helmets and goggles), and medical devices.

Epoxy resins line metal products such as canned foods, bottle tops, dental composites and sealants, and water supply pipes.

Is bisphenol A safe?
That's a controversial question.

An FDA draft report issued in August 2008 says bisphenol A is safe at typical exposure levels from food and drink. But another government report, from the National Toxicology Program, doesn't rule out safety risks and notes "some concern" about effects on the brain, prostate gland, and behavior in fetuses, infants, and children.

The NTP's report, issued in September 2008, also notes "minimal concern" about effects on the mammary gland, early female puberty, and reproductive effects in adults who work with bisphenol A, and "negligible concern" about fetal or neonatal death, birth defects, reduced birth weight or grown in babies born to women exposed to bisphenol A during pregnancy, and reproductive effects in adults who don't work with bisphenol A.

The American Chemistry Council, a trade group for the plastics industry, says bisphenol A is safe for typical consumer uses.

What does the research say about bisphenol A?
A study published in the Sept. 17, 2008 edition of The Journal of the American Medical Association shows that adults with high levels of bisphenol A in their urine samples are more than twice as likely to report a history of heart disease or diabetes, compared to adults with low urinary levels of bisphenol A.

That study was the first to show an association between higher urinary levels of BPA and health problems in human adults. But it doesn't prove that bisphenol A causes heart disease or diabetes, and the researchers caution that their findings need to be confirmed.

Much of the other bisphenol A safety research has been done on rodents, which handle bisphenol A differently from humans. In those rodent studies, the greatest risk has been seen in developing fetuses and infants.

How are people exposed to bisphenol A?
Mostly through food and drink packaged in containers that include bisphenol A.

Bisphenol A can leach into food from food and beverage containers lined with epoxy resin coatings and from products such as polycarbonate tableware, food containers, water bottles, and baby bottles.

Does heating polycarbonate products or cleaning them in a dishwasher increase leaching of bisphenol A?
Yes, but not enough for concern, according to the American Chemistry Council. "Although the level increases slightly, it's still far below the science-based safety standard by at least a factor of 100 or so," says Steven Hentges, PhD, of the council's Polycarbonate/BPA Global Group.

But that, too, is controversial. In January 2008, a University of Cincinnati researcher who studied polycarbonate plastic exposed to boiling liquid told WebMD that while there is little direct evidence that bisphenol A poses a risk to humans, he sees "clear reason to proceed cautiously."

Who is exposed to bisphenol A?
Just about everybody. Nearly 93% of Americans age 6 and older who took part in a CDC health study in 2003-2004 had detectable levels of bisphenol A in their urine samples.

How can I avoid bisphenol A?
Here are tips posted on the web site of the National Institute of Environmental Health Sciences, a branch of the National Institutes of Health:

* Don't microwave polycarbonate plastic food containers. Polycarbonate plastic is strong and durable, but over time it may break down from use at high temperatures.
* Reduce your use of canned foods.
* When possible, opt for glass, porcelain, or stainless steel containers, particularly for hot food or liquids.
* Use baby bottles that are free of bisphenol A.

The FDA hasn't advised anyone to avoid or reduce their exposure to bisphenol A, and the American Chemistry Council says there's no reason to do so.

Totally avoiding bisphenol A isn't a reasonable goal because it's so widespread, notes David Schardt, MS, senior nutritionist at the Center for Science in the Public Interest (CSPI).

"You can't drive yourself crazy trying to eliminate every speck," says Schardt. "It's not going to happen." Schardt sees the biggest priority as limiting exposure in small children. He suggests using cardboard cartons of milk, for instance, and baby bottles or sippy cups that don't contain bisphenol A.

Other alternatives include glass bottles, but of course, those aren't shatter-resistant like polycarbonate plastic.

Are products made from bisphenol A marked as containing bisphenol A?
No. Some plastic products have labels saying that they are free of bisphenol A, but there are no required labels for products that contain bisphenol A.

Do plastic containers with "7" within the "chasing arrows" all contain bisphenol A?
No. The numbers in those "chasing arrow" symbols on the bottom of some plastic products are only about recycling.

The numbers 1-6 in the chasing arrows aren't supposed to be polycarbonate plastic, so they shouldn't contain bisphenol A. But the number 7 isn't just for polycarbonates; it's a catch-all category of plastics, and not all polycarbonate plastics have the "7" on them, notes Schardt.

Cheers, frizzy2008.