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This week's science section of The New York Times carried a story by Denise Grady summarizing the present status of the arguments over the safety of the estrogen-disrupting chemical in plastics, bisphenol A (BPA).

Who knew that supposedly scientific decisions about whether BPA is safe or not would be mired in deadlocked partisan politics of the Republican versus Democrats type? As Grady explains,

Environmental groups and many Democrats want BPA banned, blaming it for an array of ills that includes cancer, obesity, infertility, and behavior problems ... Many Republicans, anti-regulation activists and the food-packaging and chemical industries insist that BPA is harmless and all but indispensable to keeping canned food safe by sealing the cans and preventing corrosion, and to producing many other products at reasonable prices.

Dianne Feinstein (D-CA) tried to get a ban on BPA inserted into the pending food safety bill. Her plan:

to ban BPA from baby bottles, sippy cups, baby food and formula was blocked by partisan battling. She had hoped that the ban would be included in the food safety bill, not merely in an amendment to be considered separately. But after months of wrangling, she gave up. The food industry, mostly supportive of the food bill, threatened to oppose it if the BPA provision got in. So did many Republican senators.

The scientific questions about BPA safety are complicated and difficult to answer, mainly because the doses are so low. Here too, politics intervenes. The article quotes Dr. Linda Birnbaum, director of the National Institute of Environmental Health Sciences. She and other scientists say that

studies by university labs tended to find low-dose effects, and studies by government regulatory agencies and industry tended not to find them. The split occurs in part because the studies are done differently. Universities, Dr. Birnbaum said, "have moved rapidly ahead with advances in science," while regulators have used "older methods." Some researchers consider the regulatory studies more reliable because they generally use much larger numbers of animals and adhere to formal guidelines called "good laboratory practices," but Dr. Birnbaum described those practices as "good record-keeping" and said, "That doesn't mean the right questions were being asked."

In the absence of firm science, regulators have two choices: exercise caution and ban the chemical until it can be proven safe (the precautionary principle) or approve it until it can be proven harmful. In this case, I'm in favor of caution (see previous posts), not least because alternatives to BPA are available.

Your preference?

This post also appears on foodpolitics.com.