When you can't win on the evidence, invoke the law and pray the web mob will carry the water for you. Unfortunately, that has been the strategy of activists when science policy is in play.
The US Chamber of Commerce has used this tactic to thwart regulatory responses to climate change. It's become a mantra of anti-vaccine crusaders. And it's emerged as the calling card of factions in the environmental movement bullying legislatures into banning the ubiquitous plastic additive bisphenol A. California is the latest battleground.
California often serves as a vanguard for environmental standards, smart and stupid alike. Under the state's Proposition 65, the "The Safe Drinking Water and Toxic Enforcement Act of 1986", chemicals officially listed by California as causing cancer, birth defects or other reproductive harm can be restricted and mandatory labeling can be required. That makes sense in theory but challenges to science can arise in its implementation.
Up until now, the state depended on its toxic investigatory committee to make that determination, and it has consistently determined BPA is safe. But because of a legal action from the National Resources Defense Council the state may be forced to list as dangerous a chemical that its own scientists believe does not pose a public danger. The mid-July meeting of California's Office of Environmental Health Hazard Assessment (OEHHA) will provide insight into how far politics and legal maneuvering are infecting what's supposed to be a science-driven process.
Precautionary politics
The chemical in the crosshairs, known as BPA, is used in electronics, thermal paper, cars and polycarbonate plastics, from microwavable containers to sippy cup, and added to epoxy resins to create dental sealants and line metal cans to prevent spoilage.
Over the past few years, the dominant narrative among campaigning organizations is that BPA is dangerous to infants and pregnant women because it alters development. Its detractors call it an "endocrine disruptor." BPA does subtly alter the way hormones work. But so do phytoestrogens in soy, nuts, wheat, berries and other foods to no serious affect. Scientists call this endocrine mediation.
No panel of regulatory scientists in the world recommends restricting BPA based on evidence of harm. The World Health Organization, the European Union risk assessment board, the US Food and Drug Administration and Health Canada, Japan, New Zealand and Australia have all rejected restrictions on BPA based on the science.
Regulators contend that the results from most of the 200 studies cited by activists as "proof" of potential harm are contradictory and too small scale to be reliable. Scientists call them "exploratory" or "hypothesis driven" research. They are an important part of the research chain but in and of themselves are of limited value -- they are not the robust studies that regulators utilize to establish "weight of evidence."
In January 2010, the FDA issued its second analysis of BPA in two years, rejecting new restrictions. BPA "is not proven to harm children or adults" and the most reliable studies to date support "the safety of current low levels of human exposure to BPA," the FDA concluded.
It based its decision on a 2008 report by the National Toxicology Program that found BPA posed "negligible" or "minimal" concern for effects on the mammary gland and early puberty for fetuses, infants or pregnant women or their offspring. It found "some concern" for effects on the "brain, behavior and prostate glands in fetuses, infants, and children," which means "more research is needed to better understand their implications to for human health," but regulators should not act precipitously on animal data from exploratory studies.
But in the case of BPA, precautionary politics has sometimes trumped science. Health Canada's political arm and the Danish and French parliaments rejected their own scientists' recommendations and imposed precautionary bans, acknowledging such actions were based on public fears, as the "[s]cience tells us that exposure levels are below those that could cause health effects". Numerous states in the US have followed suit. But California has so far resisted. Last year, the state's Senate rejected a House proposal to ban BPA in baby bottles and other feeding products for children. But the issue lived on.
Shifting Tactics in California
Recognizing that they might not win legislative approval, activists focused on trying to ban the chemical by forcing the state's hand under Prop 65. But two years ago, California's Development and Reproductive Toxicant Identification Committee of physicians voted unanimously that BPA should not be classified as a dangerous toxicant because there was no evidence of harm to humans.
That did not sit well with the NRDC, which filed a petition to the implementing agency, OEHHA. The NRDC demanded that California ignore the recommendations and impose restrictions regardless. The NRDC's rationale? It cited the NTP report--the one used by the FDA in 2010 to reject a ban.
In bringing its petition, the NRDC cherry-picked the NTP report, misleadingly stating that it "concludes that the chemical causes reproductive toxicity" in humans. What the NRDC left out is that the highlighted studies focused on rats continuously exposed to BPA at levels 100 to 10,000 times higher than what humans are exposed to. After weighing the evidence for humans, the NTP had concluded it had "negligible concern that exposure of pregnant women to bisphenol A will result in fetal or neonatal mortality, birth defects, or reduced weight and growth in their offspring".
But the NTP's conclusions, presented in context, may not mean much to the OEHHA, as Prop 65 has a loophole as big as the hole in NRDC's scientific credibility. The act has what's called "sufficiency criteria" that mandate listing if any authoritative body "formally identifies the chemical as causing reproductive toxicity" -- even if the studies focused on rodents and the conclusions do not transfer to humans.
Scientists push back
Regulators, who rely on science rather than public opinion, must weigh the potential consequences of switching to other products with less tested chemicals just to placate public fears. That would be akin to rolling the toxic dice. Moving to glass bottles could also result in direct injuries from breakage.
As David Coggon, Chairman of the Committee on Toxicity in the UK, said recently to the UK Food Safety Authority's spring issue of Bite magazine, "BPA has estrogenic properties" but that does not imply a health risk. "As with all chemicals, risk depends on the extent to which a person is exposed. ... The ban on BPA in baby-feed bottles is not based on scientific evidence of harm or even on a strong suspicion that it could be harmful."
Independent scientists at the FDA take an equally dim view of demands. During the January 2010 news conference announcing the FDA's decision opposing a ban, Joshua Sharfstein, M.D., then the agency's principal deputy commissioner, minced no words. "The FDA does support the use of bottles with BPA because the benefit of nutrition outweighs the potential risk of BPA," he said. "If we thought it was unsafe, we would be taking strong regulatory action." The NRDC subsequently sued the FDA for allegedly failing to take timely action to ban BPA, but the courts rejected the lawsuit in early June.
Over the past two years the science consensus has moved sharply away from the speculative hypothesis that BPA is an "endocrine disruptor". The FDA has been joined by the European Food Safety Authority in summer 2010, a joint UN Food and Agriculture Organization/WHO expert panel on BPA in November 2010, and an Advisory Committee of the German Society of Toxicology last spring in concluding that the collective evidence demonstrates that BPA does not pose serious neurological dangers or cause cancer in humans, and has not an "endocrine disruptor."
FDA/CDC study challenges activist claims
One by one the central contentions promoted by anti-BPA campaigners have fallen in the face of more robust studies. The latest revelation came last month. It's been widely reported by campaigners that BPA shows up in the urine of more than 90 percent of people. Are such levels dangerous? "Biomonitoring studies clearly show BPA is present in the human body at levels that are concerning for health impacts," asserts NRDC's Sarah Janssen. "Therefore, the fetus is being exposed to a toxic form of BPA during extremely vulnerable periods of development."
But the latest research, a state-of-the-art study co-sponsored by the FDA and the CDC and published in Toxicological Sciences in June, directly contradict the NRDC's claim. Rather than studying animals, this research involved human volunteers exposed to high levels of BPA by eating canned food and beverages from plastic bottles. Justin Teeguarden, senior research scientist with the Pacific Northwest National Laboratory and his team of government-funded researchers conclude that human exposure to BPA is extremely low and it's highly unlikely that the chemical could cause health effects in humans as it is efficiently metabolized and excreted.
Richard Sharpe, head of the Centre for Reproductive Biology at the Medical Research Institute in Edinburgh interpreted the results for Trevor Butterworth of STATS and a Medialand columnist at Forbes.com. Sharpe calls the study "majestically scientific and cautious":
This is what I would term a classic study ... with clearcut results (that fit in well with the majority of published data) that carry with them fundamentally important implications. ... [T]he general population [is] essentially exposed internally (i.e. our working tissues and cells) to minute levels of BPA after we eat foods that are known to be the main source of our BPA exposure. Indeed the levels are so low that often they cannot be measured. ...
It means that the majority of effects observed in animal studies are probably not relevant to humans because they involved much higher BPA exposures. ... [T]he authors ... take one example from the literature of a high quality animal study ... in which BPA exposure was measured and show that even in this scenario, one would have to conclude that such effects would not occur in humans unless we are 100 to 10,000 times more sensitive to BPA effects than are rats. ... [T]his seems inherently unlikely. So the take-home message is: BPA is highly unlikely to induce any effects in humans because we simply are not normally exposed to anywhere near enough BPA to cause such effects. ....
As Sharpe notes, studies are continuing on possible other effects, but nothing definitive yet presents itself. His comments are noteworthy as he has no industry ties and is a recognized pioneer on the effects on endocrine mediation. He was also an early believer in the "endocrine disruptor" thesis.
"Just apply common sense," Sharpe commented recently. "If several studies using the human-relevant route of exposure show no effect but a small preliminary study does show effects, which would you believe? ... The overwhelming scientific evidence says that bisphenol A is not a risk to human health."
A growing consensus of scientists are convinced that the "endocrine disruptor" hypothesis is dead, and precious research funds should be directed elsewhere. When or if dedicated anti-BPA campaigners yield to the emerging science remains to be seen. Let's hope the OEHHA has the wisdom and courage to base its decision on science rather than on a narrow interpretation of Proposition 65.
Jon Entine, senior fellow at STATS and the Center for Health & Risk Communication at George Mason University, and director of the Genetic Literacy Project, is author of "Scared to Death: How Chemophobia Threatens Public Health