August 9, 2007 The Pump Handle 0Comment

The expert panel evaluating the chemical bisphenol A for the National Toxicology Program has “some concern” that BPA exposure causes neural and behavioral effects in developing fetuses, infants, and children. The panel has “minimal concern” or “negligible concern” that BPA affects the prostate or causes premature puberty or birth defects. (PDF draft meeting summary here)

Several scientists and health advocates have expressed far more concern about the effects of BPA, an estrogen-like compound that’s found in plastic and also in most of our bodies. Last week, 38 scientists published a consensus statement in the journal Reproductive Toxicology that concluded, “The wide range of adverse effects of low doses of BPA in laboratory animals exposed both during development and in adulthood is a great cause for concern with regard to the potential for similar adverse effects in humans.” (Living on Earth, which aired a segment on BPA last week, has posted a PDF of the statement.)

Marla Cone at the LA Times explains what the panel reviewed and why it characterized the risks as it did:

The panel reviewed about 500 animal studies, many of which reported that the estrogen-like chemical alters various functions and parts of the body. Some have found altered brain development, precancerous changes in prostates and mammary glands, low sperm counts, and damage to the uterus. Plastics industry representatives say the lab experiments are inconclusive and flawed.


Part of the reason the panel ranked the risks as less serious than did the other group of scientists is that the panel rejected several dozen animal studies that found reproductive effects. In those studies, animals were exposed through injections, rather than through their diet. The decision to reject the studies has been controversial with toxicologists.

Controversy has shadowed this process for the past several months. Environmental health advocates and a previous Marla Cone story drew attention to the chemical-industry ties of the company NTP contracted to draft the preliminary BPA report; NTP fired the contractor, but last week reported that an audit had found no impropriety in the preliminary report’s preparation. (This case highlights the larger problem, which is the lack of adequate agency policies to identify and address contractors’ potential conflicts of interest.)

Scientists at the Natural Resources Defense Council and Environmental Working Group have detailed their concerns about the inclusion or exclusion of particular studies during this process. In a statement about the panel’s conclusions, EWG Senior Scientist Dr. Anila Jacobs said, “While expressing “some concern” about the neural and behavioral impacts of fetal exposure to low doses of BPA, the panel rejected the independent studies tying this chemical to breast and prostate cancer, obesity, and reproductive problems.”

Marla Cone got a reaction from Frederick vom Saal, one of the foremost researchers on BPA and corresponding author of the consensus statement published in Reproductive Toxicology:

Frederick vom Saal, a University of Missouri-Columbia reproductive toxicologist who has conducted studies on BPA, was disappointed that the panel did not rank the risk higher. But, he said, “the panel is now on record saying there are human health concerns.”

The panel’s statement of concern is only one step in a longer process:

[The panel’s] recommendations will go to the National Toxicology Program, the federal scientists who help regulators mold policy about toxic substances. Officials there will send their report out for review by other scientists before deciding whether to declare BPA toxic to humans. [NTP Associate Director John] Bucher said he would also update it with the consensus statement and studies published last week.

The final report could trigger a review of BPA by California officials under Proposition 65, which requires warnings on consumer products that pose a risk of cancer or reproductive harm.

If you’re not already concerned about BPA, Liza Gross’s PLoS Biology article on endocrine-disruption research might raise your concern level a notch or two.

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