One of the most disturbing trends in science reporting is what The New York Times’ Andrew Revkin calls “single-study syndrome”— the increasing tendency of reporters and non-governmental organizations (NGOs) to trumpet research that supports a pre-determined perspective, no matter how tenuous—or dubious—a study might be.
That tendency was in sharp display recently after the publication of a study on Bisphenol A by University of California structural biologist Michael Baker in the online journal PLOS ONE. The chemical—a ubiquitous additive found in common plastic products and used as an ingredient in epoxy liners in cans that prevent spoilage and botulism—has been in the crosshairs of a small but determined group of university researchers, activist NGOs and journalists.
Critics of BPA believe it causes a range of disorders, particularly in pregnant women, developing fetuses and infants. They call it an “endocrine disruptor,” a term that gradually crept into mainstream use to describe synthetic chemicals that “mediate” hormonal activity, as do many natural substances, such as soy. BPA, they claim, is one chemical in a rogue’s gallery that includes the common weed killer atrazine, plasticizer phthalates and chemicals used to produce resins and detergents.
As often happens when a new study on BPA or “endocrine disruption” is published, a chorus of what seems like coordinated reactions materializes on the web. Within hours of the release of the Baker study, cyberspace exploded. The University of California-San Diego Health System’s news release, breathlessly titled, “BPA’s Real Threat May Be After It Has Metabolized,” was picked up verbatim by thousands of websites. It sparked uncritical stories by Chemical & Engineering News, Yahoo!, numerous other reputable news outlets and hundreds of speculative pieces by chemical-fearing NGOs with headlines ranging from “BPA is Bad to the Bone, Now We Know Why,” to “BPA Can be passed from moms to kids at birth” and “New studies add fuel to concerns over BPA.
The news reports shared a common theme—asserting or at least suggesting that the Baker study was a smoking gun and perhaps the final scientific word that activists have been awaiting to confirm their long-held belief that BPA is harmful and should be banned or sharply restricted. The irony is that the Baker study, when analyzed, does not support that view. Rather, it provides additional confirmation of the unlikelihood that BPA or many other so-called “endocrine disrupting” chemicals pose serious health threats.
The bizarre journalistic reaction to the Baker study underscores a distressing turn in “science reporting”—a disconnection between what agenda-seeking NGOs and their partners in the popular media report versus what the empirical evidence suggests. BPA antagonists range from chemophobic “natural” activist groups (Healthy Children Healthy World, Joseph Mercola) and advocacy media organizations (Mother Jones, Grist) to popular environmental organizations (Environmental Working Group, Natural Resources Defense Council). They share a worldview with some high-profile journalists—most notoriously the columnist Nicholas Kristof of The New York Times. Kristof has made “endocrine disrupting” chemicals one of his signature issues—much to the embarrassment of top-flightscience journalists. This loose but very real coalition also includes reporters at many otherwise reputable news organizations who are not necessarily locked into a view about BPA or chemicals in general but, based on their reporting, appear to have only a superficial understanding of scientific risk.
According to these critics, chemicals like BPA can be blamed for everything from cancer to obesity, retarded neurological development, diabetes, cardiovascular disease, infertility and other disorders related to sexual development. These are catastrophic allegations, which if supported by the evidence warrant immediate and decisive restrictions. But in the case of BPA, the very opposite is happening. Since 2007, there have been more than a dozen comprehensive reviews of BPA by independent government scientists around the world, including in Canada, Europe, Japan, Australia and the United States, and each has concluded that the current uses of the chemical are safe.
In fact, the same week the Baker study was released—and ballyhooed by activist bloggers and journalists as decisive new evidence—Health Canada and that country’s Bureau of Chemical Safety upheld its prior scientific finding that found BPA poses no serious threat. “Based on the overall weight of evidence,” reads the report, “the findings of the previous assessment remain unchanged and Health Canada’s Food Directorate continues to conclude that current dietary exposure to BPA through food packaging uses is not expected to pose a health risk to the general population, including newborns and young children.”
Is BPA bioactive?
The most common and seemingly damning allegation against BPA, and one that shows up repeatedly in media reports, is that the Centers for Disease Control and Prevention (CDC) has found traces of the chemical in the urine of more than 90% of adults and children. That sounds frightening. But is it cause for concern? How scientists and journalists frame this often-stated fact is a good barometer of their understanding of risk analysis—whether they genuinely wrestle with complex science or are mouthpieces, intentionally or not, for a predetermined, chemophobic perspective.
The CDC has repeatedly stated that while biomonitoring “can … help scientists plan and conduct research on exposure and health effects,” the presence of a chemical in urine—whether BPA, atrazine, a phthalate or some other chemical targeted by advocacy groups—is not necessarily a sign that it’s harmful. Because advanced biomonitoring technology can detect vanishingly low concentrations of chemicals, “[f]inding a measurable amount of BPA in the urine does not mean that the levels of BPA cause an adverse health effect,” the CDC has written.
Regulators and most scientists believe the central focus of research should be to determine whether a bioactive form of a chemical makes it through the liver into our bloodstream, where it could effect our health. Years ago, that issue had been in doubt, which is why many scientists were initially agnostic over the question of BPA’s potential health impact. But by 2010 the FDA, reflecting the emerging scientific consensus, concluded, “[O]ral BPA administration results in rapid metabolism of BPA to an inactive [and therefore harmless] form.”
Such declaratory statements, echoed by every major international agency before and since, have not mollified the determined proponents of the endocrine disruption hypothesis. They remain convinced that Paracelsus’ famous declaration—“the dose makes the poison”—which has been the defining standard in toxicology, risk assessment and regulatory oversight—is simplistic and outdated. They believe in what’s called the non-monotonic response: A class of substances, BPA included, can interact with cellular hormone receptors in such a way that lower doses can pose higher risks.
Indeed, studies have shown that low doses of certain chemicals can induce non-monotonic effects. There are more than 600 studies to date according to a survey published last March in Endocrine Reviews. But independent scientists who have reviewed these studies, time and again, have come away unconvinced these effects consistently or even generally suggest harm. For the most part, they see biological activity—lots of statistical noise with contradictory indications of harm. And in the overwhelming majority of cases in which effects have been seen, rodents were administered the chemical by injection, bypassing the oral route, which is how humans typically encounter these substances. Regulators view these studies as marginally relevant to assess human health.
What’s an “endocrine disrupting” chemical?
Four years ago, in light of their unwavering and highly publicized concerns over BPA, the organized group of scientists who embrace the endocrine disruption hypothesis demanded, and were granted, yet another round of independent, government-financed peer review studies. The Obama Administration authorized under the stimulus package more than 30 million dollars for new research. The first set of studies began to appear in 2010. As the evidence began to come in and much to the discouragement of a shrinking group of true believers, the mainstream scientific consensus began to shift away from their position.
Originally open to considering that BPA might be harmful, L. Earl Gray Jr., senior scientist at the Environmental Protection Agency’s Research Triangle center in North Carolina, and his colleagues addressed whether endocrine effects translate into “endocrine disruption.” Their government-funded study, published in 2010, covered a wide range of BPA doses. It found extremely weak effects at low and high exposure levels. Even at four thousand times higher than the maximum exposure of humans in the general population, there were no discernible effects. Gray and his co-authors concluded that BPA has an extremely mild estrogenic impact but should not be called an “endocrine disruptor.”