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Aug. 24, 2007 -- The jury is still out on whether there's a health risk from bisphenol A (BPA), a chemical that leaches from plastic baby bottles, food/beverage cans, and many other products.
Industry uses more than 6 billion pounds of BPA every year to make the resins that line food cans and the polycarbonate plastics used to make baby bottles and many, many other products. The CDC says that 95% of us carry measurable amounts of BPA in our blood.
Some scientists say there's reason to worry. They note that BPA acts like the sex hormone estrogen -- indeed, BPA was originally developed as a chemical estrogen. These researchers worry that BPA is behind hormone-linked trends in human health such as increased abnormal penis development in males, earlier sexual development in females, increases in neurodevelopmental diseases such as ADHD and autism, increased child obesity, decreased sperm count, and more breast and prostate cancers.
The plastics industry says there's nothing to worry about. Industry-funded studies by the Harvard Center for Risk Analysis and the Gradient Corporation say there's not cause for alarm.
A scientific panel asked by the National Toxicology Program to settle the issue says there's "some" concern about neural and behavioral effects from BPA exposure in fetuses, infants, and children.
The panel found no major health risks. But there are serious questions about the panel's report -- and about its independence from industry (the contractor that prepared the panel's draft report was fired for apparent conflict of interest).
This fall, the National Toxicology Program is expected to issue a ruling on whether BPA is toxic. Until then, here's a summary of what is known -- and what you can do if you feel you're at risk.
There's no argument that at some level of exposure, BPA is toxic. BPA has a half-life in the human body of about six hours. But because we're continually exposed, nearly all of us have measurable blood levels of BPA.
Whether these levels are dangerous isn't known for sure. One problem is that BPA acts like a hormone. This means that low doses may have effects not seen at higher doses. This is a problem for traditional toxicology studies, which usually try to find a high-dose effect and lower the dose until that effect goes away.
Currently, the EPA?says that the "safe" level of BPA is set at 50 micrograms per kilogram of body weight per day. But animal studies suggest that this level of BPA has harmful effects, including genetic damage. Exactly how to translate these animal findings into human effects is a bone of contention between academic and industry scientists.
Nevertheless, BPA can flip the estrogen switches on cells at part-per-trillion concentrations -- lower concentrations than those common in the blood of human infants, children, and adults.
A panel of 38 BPA researchers recently issued a report saying they are "confident" that:
The National Toxicology Program's expert panel says there's "some concern" that fetal exposure to BPA affects a baby's brain and causes later behavioral problems.
However, the panel also found:
The American Chemistry Council supports the panel's findings. The Environmental Working Group, a watchdog group that presses for BPA regulation, blasts the report.
Canned food appears to be the main source of BPA for most people.
Last March, the Environmental Working Group reported the results of a study in which a national analytical laboratory tested 97 cans of food for BPA. The cans?were purchased at supermarkets in Atlanta; Oakland, Calif.; and Clinton, Conn.
The study found that:
BPA is an ingredient in many plastic products. A conservation group, the Institute for Agriculture and Trade Policy, notes that plastic bottles with the recycling number 7 (except new bio-labeled plastics) usually contain BPA.
Plastic baby bottles and "sippy" cups often contain BPA. Concerned parents should avoid using these products if they are old, scratched, or have a cloudy, cracked appearance.
To limit BPA exposure, the Environmental Working Group recommends:
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