Scitech | Plastic poison resists regulation

Calls for regulation of chemical BPA fall on deaf ears

It runs in the blood of almost every person in the world. The chemical is Bisphenol A (BPA), a synthetic estrogen that has been used in plastics for decades and interferes with fetal development. In mice it can change the structure of genitalia, reverse sexual differences in the brain, and increase susceptibility to prostate and breast cancers. And although it may cause heart disease and diabetes in humans, few seem to care.

Canada began to evaluate the chemical in 1999 when it was first detected in human serum. Since then, evidence for BPA’s toxicity has accumulated, and this September a paper by Dr. Iain Lang and colleagues established a correlation between BPA and human diseases such as heart disease and diabetes.

Canada labelled BPA as toxic earlier this year, a designation that allows ministers to regulate its use. Baby bottles containing BPA were banned, and many drink companies took bottles containing BPA off the shelves. So far, no other country has followed suit.

According to Dr. Wade Welshons, a professor in the endocrine disruptors group at the University of Missouri, the lack of regulation in other countries is a result of industry’s efforts to keep the ten-billion-dollar per year industry going.

“BPA [constitutes] such a large and lucrative market that it just carries itself along. In 1999, the chemical industry hired a tobacco industry lobbyist – the Wienberg group – to protect the product. They did a very thorough job of creating doubt that second-hand smoke was dangerous, and the same kind of techniques are just being applied more broadly to BPA,” Welshons said.

The industry response to the Lang paper is a typical example of such techniques. Officials are emphasizing that the Lang paper did not find that BPA causes disease, but only that it is correlated with it.

It is important to note, however, that to confirm causation researchers would have to inject human subjects with BPA – which is illegal – and observe their health.

Researchers instead use animal subjects, like mice and rats, to study causation. Through such studies, they have found that BPA does cause health deterioration, which might substantiate a causative relationship between BPA and disease.

Stephen Hentges, of the pro-industry American Chemical Council, ignored the numerous studies on animal models when he dismissed the Lang paper for not establishing causality.

“At least from this study, we cannot draw any conclusion that BPA causes any health effect…. Further research will be needed to understand whether these statistical associations have any relevance at all for human health,” he said in a September interview with Reuters.

Welshons does not applaud this view.

“That’s the usual absurd comment,” he said.

Despite suggestions of BPA’s adverse effects on health, firmer evidence is still needed to convince regulators such as the FDA – who resist the idea of killing off such a lucrative industry – that BPA should be restricted. According to Dr. Robert Wallace, a co-author of the Lang paper and an epidimiologist at the University of Iowa, that may be difficult to achieve.

“It’s a scientific problem that has many dimensions. The approach is to triangulate different studies of tissues, lab animals, and cell cultures, all of which have a cumulative effect. What we’d like to do from a human perspective is find a population of people whose exposure to BPA is known and follow their health over a number of years,” Wallace said.

But while scientists spend years building an unassailable fortress of evidence that BPA causes disease, the chemical continues to tamper with fetal development and potentially harm adult health. The vast majority of people have BPA in their serum; it leaches from the plastic lining of canned foods and water bottles, for example, and is often present in tap water. A 2007 consensus statement by 38 BPA experts noted that most adults have BPA levels above those that harm animals. According to Maricel Maffini, a professor at Tufts University, regulatory agencies shouldn’t wait on studies that may take many years.

“Because these studies are so long- term, research on laboratory animals needs to be taken more seriously. In any science you do, animals are considered a gold standard – except in the field of endocrine disruptors like BPA,” Maffini said.


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