Published: Sept. 19, 2008
Updated: Aug. 16, 2010
The controversy behind BPA and your health
For decades, the chemical known as bisphenol A (BPA) has been an odorless, tasteless part of clear, shatterproof polycarbonate plastics such as baby bottles, as well as the epoxy resins that line many food and drink cans. Though durable and versatile, these ubiquitous containers have had a recent streak of bad publicity as scientists continue to look into the potential effects of BPA consumption. Many don’t like what they’re seeing.
“Think of BPA as a food additive,” says Duke researcher Randy Jirtle, PhD. “When these containers come into contact with acid or heat, BPA begins to leach into the food or liquid that’s in them.”
After that -- well, it’s still a matter of debate among scientists. BPA mimics estrogen; its half-life is a mere six hours, but we are constantly exposed to it. In 2007 the Centers for Disease Control and Prevention (CDC) reported detecting BPA in the urine of nearly 93 percent of 2,517 Americans tested (age six and up). But what level of human exposure leads to which effects, if any, isn’t yet known.
Researchers in Jirtle’s lab have proven that for mice, BPA exposure in the womb -- an especially sensitive period -- points to obesity, diabetes, high blood pressure, and delays in brain development. “BPA didn’t change their genes, or their ‘hardware,’" says Jirtle.
“But BPA did affect their epigenome, the ‘software’ that tells the genes how to express themselves. BPA effectively put bugs in the software, and it didn’t end with one generation. If our findings are echoed in people, that would mean the effects of BPA can potentially be inherited.”
To counter the effects of BPA, the mice in Jirtle’s lab were given genistein, a plant estrogen found in soy products like tofu. “When the mothers were exposed, it didn’t just reduce the negative effects of BPA -- it completely blocked them,” he says. But Jirtle warns against battling BPA with an all-tofu diet. “As a society, we have a bad habit of thinking that if something is good, a lot must be better.”
So, what should consumers do in the battle over BPA? Jirtle himself eschews the stuff, but other researchers are unsure about the true harms of the substance, which has been documented as an artificial estrogen since the 1930s.
We asked two Duke toxicologists -- both of whom made clear that they are not experts on BPA -- what they thought of the risks associated with BPA contamination in food products.
Woodhall Stopford, MD, says he did a brief assessment when his grandchild was born, and was “not impressed” by the potential risks from using plastic baby bottles.
Dennis Darcey, MD, says that though the ultimate risks aren’t clear, “prudent avoidance would seem to be a reasonable approach,” especially when there are substitutes. These days it’s easy to find BPA-free baby bottles and water bottles -- look for bottles with the recycle numbers 1, 2, 4, and 5, and avoid 3, 6, and 7 -- though Jirtle points out that canned foods haven’t received the same public and media scrutiny.
“And until consumers use the power of their wallets,” he says, “there’s no incentive for companies to change anything.”
Note: Plastic bottles labeled with the recycling number 1 are designed for one-time use only -- they should be recycled instead of reused.