STATS ARTICLES 2010
World Health Organization says donít ban BPA
Trevor Butterworth, November 10, 2010
The evidence that thereís a risk to health is too weak for regulatory actions says international expert panel. Ongoing research will clarify relevance of novel claims and experiments.
An international panel of experts convened by the World Health Organization to examine the health risks from exposure to the chemical bisphenol A (BPA) agreed that it would be “premature” to take any public health measures to regulate or ban the chemical.
This conclusion was in light of the robust evidence that human exposure to BPA, primarily through food, did not result in accumulation in the body and was rapidly excreted in urine.
Previous regulatory research has concluded that BPA – widely touted by environmental activists as an endocrine disruptor – lost its estrogenic power through the way it was metabolized in the body. The WHO panel noted the chemical was rapidly excreted in urine, and that any circulating level of BPA in the blood was very low.
The WHO panel, which was organized with FAO, and was supported by European Food Safety Authority, Health Canada, the US National Institute of Environmental Health Sciences and the US Food and Drug Administration, said that food is the primary source of BPA exposure – and that soil, dental sealants and cash register receipts – recently the subject of scare stories in the media – were of “minor relevance.”
A recently published study by scientists at the University of Texas School of Public Health found that BPA levels in food were 1000 times lower than the Tolerable Daily Intake (TDI) level established by the European Food Safety Authority (EFSA) and the US EPA.
The WHO’s conclusions mirror EFSA’s recent decision that the evidence against BPA was weak, and that recent concerns did not stand up to methodological and statistical scrutiny (for more on this decision, see STATS report on the EFSA review).
The WHO panel noted that while “a few recent experimental and epidemiological studies found associations between low BPA exposure levels and some adverse health outcomes… it is difficult to interpret the relevance of these studies in the light of current knowledge of this compound.” There are, the panel said, several ongoing studies that will resolve the questions raised by this research.
Poor methodology and statistics have dogged the handful of scientists who have been trying, for over a decade, to claim that BPA was “the biological equivalent of global warming.” Such claims have led to environmental activist groups such as the National Resources Defense Council and the Environmental Working Group to lobby for a ban on the chemical, and these attempts have received the support of newspapers such as the Milwaukee Sentinel Journal, prominent columnists such as the New York Time’s Nick Kristoff, and politicians such as Sen. Diane Feinstein (D-CA).
Unfortunately, the media has done a poor job covering the arguments against the evidence supporting these claims, in part because the regulatory agencies have done a poor job of translating complicated technical research into language that journalists and the public can understand, and in part because studies that fail to replicate controversial claims tend, in general, not to generate media coverage.
Last year, Richard Sharpe, the Chairman of the United Kingdom’s Expert Panel on Endocrine Disruption, and an international expert on the risks of chemicals to human reproduction, wrote that the refusal to face up to the ongoing failure to replicate the studies claiming that BPA is a threat to health was undermining the credibility of science.
In April, he addressed concerns in Britain about the safety of BPA in several interviews with newspapers, telling readers to “apply common sense – if several huge studies using the human-relevant route of exposure show no effect but a small preliminary study does show effects, which would you believe?... There is always a danger that people's ideals, particularly those of lobbyists and campaigners, can make them pick and choose the science that suits them. In this case the overwhelming scientific evidence says that bisphenol A is not a risk to human health.”
This is the essential problem with the media’s coverage of BPA. The small, preliminary studies generate alarming headlines about BPA being associated with all manner of diseases, while the follow up research explaining why the statistics and methodology don’t add up go ignored.
The situation has caused enormous frustration among regulatory scientists. Robert Chapin, a toxicologist who chaired an expert panel on BPA convened by the National Toxicology Program’s Center for the Evaluation of Risks to Human Reproduction (CERHR), told STATS that key scientist driving the push to ban BPA, the University of Missouri’s Frederick vom Saal, did “miserable studies which should not be given the weight they were receiving.”
The problem of erroneous, peer-reviewed health research has recently received attention thanks to an Atlantic Monthly profile of medical mathematician John Ioannidis, who, in statistical and methodological audits of published research, has found substantial and widespread error along with poor experimental design.
The WHO panel findings, coming after EFSA’s review of the state of the science on BPA, reinforces the fundamental importance of statistical and methodological rigor in understanding whether the chemical is a threat to health or harmless.