The industry group for the widely used plastic compound bisphenol A, currently the subject of a safety assessment by Health Canada, bases its view that low exposures to the chemical are harmless on three studies it funded – research that critics contend contains serious flaws.
The American Chemistry Council, an Arlington, Va.-based lobby group, has submitted the studies to Health Canada for its assessment. But only one of them has been published in a peer-reviewed journal, the process that allows research to be vetted by independent experts.
Bisphenol A, or BPA, is one of the most commonly used synthetic chemicals, but has been dogged by controversy because its molecular shape allows it to act like estrogen in living things. And trace amounts of the substance leach from such consumer products as polycarbonate baby bottles. Dozens of independent studies have linked small exposures to hormonally related illnesses, such as some types of cancer, but council-supported research hasn’t detected these harmful effects.
Health Canada identified the three council-funded studies in response to questions from The Globe and Mail about submissions showing the chemical doesn’t pose risks.
The published study, which appeared in 2002 in the journal Toxicological Sciences, was criticized because it involved feeding bisphenol A to a strain of rats not overly responsive to estrogen, and failed to include a test that would have revealed the rodents weren’t appropriate for investigating hormone-mimicking chemicals such as BPA.
Of the other two studies, one is awaiting publication, which will place it in the public domain, and the third, according to a spokesman for the council, wasn’t “of great relevance” to the controversy over whether small exposures to BPA are dangerous. The third study subjected test animals to extremely high doses of BPA, but was given to Health Canada because it was part of the historical research record on the chemical, according to council spokesman Steve Hentges.
Health Canada has deemed bisphenol A a potentially harmful substance based on a preliminary assessment and has challenged the industry to provide information that would support the case for continued public exposure to it. The federal department expects to issue its final assessment next month.
The council represents four of the five North American manufacturers of bisphenol A: Bayer AG, SABIC Innovative Plastics, Sunoco Inc., and Dow Chemical Co. The other producer is Hexion Specialty Chemicals.
There are approximately 160 non-industry-funded studies by academics and other investigators on low-dose BPA exposures, and about 90 per cent of them have detected harmful effects, says Frederick vom Saal, a University of Missouri researcher who is keeping a running tally on the scientific dispute over the chemical.
He has published a study on the council’s rat experiment and, in an interview, said the animals were so insensitive to estrogenic hormones that they wouldn’t have reacted even to birth control pills, limiting the value of any findings based on it.
The study awaiting publication, which dosed mice with BPA, did determine in advance that the animals were sensitive to estrogen, Mr. Hentges said.
Rick Smith, executive director of Environmental Defence, a Toronto-based advocacy group that has lobbied for a ban on BPA in food and beverage containers, says the industry studies “should be given very little weight” because of the questions about their validity.