Issues > May/June 2006 (#114) > The Bisphenol-A Debate: A Suspect Chemical in Plastic Bottles and Cans

The Bisphenol-A Debate: A Suspect Chemical in Plastic Bottles and Cans

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Plastics manufacturers do not deny that BPA is found widely in canned foods and beverages and is routinely ingested. They part ways with vom Saal and other scientists over the human health risks. The levels that leach into food are well below the safety thresholds set by the Environmental Protection Agency (EPA), and the plastics industry website, Bisphenol-A.org, says the chemical is completely safe unless you ingest 1,300 pounds of canned and bottled food daily. In other words, even a canned-food addict will likely ingest 500 times less BPA than the danger level set by the EPA and 100 times less than the standard set by the European Commission Scientific Committee on Food. And common sense tells us that if higher doses are safe, then lower doses must be too, right?

Not necessarily, says vom Saal, who notes that these safety levels are based on 1980s toxicity studies in rats. In those studies, conducted at relatively high doses, the only sign of toxicity was reduced body weight. However, when it comes to hormone disruption, different doses can activate or suppress different genes, vom Saal explains. "That's why early toxicity studies found that the high doses were safe. The studies didn't look at the low doses that are now proving to cause a myriad of harmful effects in animals, including chromosomal damage in female egg cells and an increase in embryonic death in mice. A follow-up to this is a study indicating a relationship of BPA blood levels to miscarriages in Japanese women," he says.

BPA was thrust into the spotlight by a laboratory mishap. In August 1998, geneticist Patricia Hunt, Ph.D., now at Washington State University in Pullman, noticed that chromosomal errors in the mouse cells she was studying had shot up—from 1 or 2 percent to 40 percent, as published in the April 2003 Current Biology. Hunt traced the effect to polycarbonate cages and water bottles that had been washed with a harsh detergent. When her team replaced all the caging materials with non-polycarbonate plastics, the cell division returned to normal.

But not all scientists think BPA is capable of doing such harm to humans. Some deny that BPA disrupts hormones. A study funded by the Society of the Plastics Industry and published in the July 2002 Toxicological Sciences that explored the effects of low doses on three generations of rats found no effect on reproduction or development. "If you look at all the data together, you don't find a consistent pattern of effects that are characteristic of an estrogenic chemical," says Steven G. Hentges, Ph.D., executive director of the Polycarbonate Business Unit at the American Plastics Council. Others argue that rodent studies such as Hunt's are not relevant to humans. A study published in the October 2002 Chemical Research in Toxicology of human volunteers found that a human body neutralizes and excretes BPA far more rapidly than a rat's body does.

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