Low Dose Exposure and the Naysayers
BPA plastic bottles

That sounds like the name of a rock band, I know, but the headline actually refers to an important scientific struggle over the health effects of exposures to even relatively small amounts of dangerous chemicals.

BPA (found in plastics).  Dioxin (highly toxic byproduct of various industrial processes).  Atrazine (a widely used herbicide).

Dangerous chemicals, right?  One would think that it would be easy and obvious to associate these well-known chemicals with harmful consequences to human health and also to wildlife.  When there is a well-funded, highly motivated lobby resisting the weight of scientific findings, then that lobby can create a scientific debate.

Who could possibly be interested in resisting that highly toxic chemicals, even at lower doses, can have adverse health effects?  Why, the chemical industry, of course.

In the forthcoming (June 2012) issue of Endocrine Review, a team of researchers, led by Laura N. Vandenberg, of the Center for Regenerative Biology at Tufts University, has published a review of the medical and scientific literature on endocrine-disrupting chemicals (EDCs) and their impact, even at relatively low doses, on human and environmental health.  A copy of the journal article can be found at:  http://edrv.endojournals.org/content/early/2102/03/14/er.2011-1050.full.pdf.

The 79-page article, including nearly 1,000 citations to the literature, examines the links between exposure to relatively low doses of EDCs and hormone-altering health effects.  The significance of this elaborate review, as the authors state up front, is that these findings challenge the traditional notion of cause and effect in cases of chemical exposure, namely that “the dose makes the poison.”

The industry doubters and deniers, especially those who are paid and supported by the chemical industry to question the science linking exposure and adverse health effects, for decades have argued that more exposure and higher doses are needed to establish a scientific link to cancer or some other health impact.   If dangerous exposure occurs only at higher levels of dose, once can see how this would be very appealing for industry.

If there are safe levels of exposure to known dangerous chemicals, then there can be “protections” for workers.  Regulators can set standards for cleaning up contamination that spares polluters from addressing anything but the most serious environmental problems.  And companies can claim their products or their industrial waste are not responsible for an individual’s unfortunate illness or death.

The Vandenberg team’s review sets out the data to support the conclusion that there are indeed biological effects in animals, on other wildlife and in humans from even low doses of certain chemical exposures.  “As discussed several times throughout this review,” the authors note, “there is now substantial evidence that low doses of EDCs have adverse effects on human health. . .The weight of the available evidence suggests that EDCs affect a wide range of human health endpoints that manifest at different stages of life, from neonatal and infant periods to the aging adult.”

The practical implications of the study’s findings are clear:  “Thus, it is logical to conclude that low-dose testing, followed by regulatory action to minimize or eliminate human exposures to EDCs, could significantly benefit human health.”

For example, the Vandenberg team explores the literature regarding BPA, an EDC found in plastic products like water bottles.   Concerns mounted over BPA when it became apparent that quantities of this chemical leached out – say, into the water in a plastic bottle – even under normal conditions

According to the study authors, BPA has been the focus of more than 200 published animal studies, many of them examining the effects from even small doses of BPA.  Many studies, using different designs and approaches have identified impact on the prostate and mammary glands.

The authors are candid in disclosing that some studies looking at potential impact from lower dose exposures have showed no adverse effects.  But the authors point out, “Essentially, all scientists know that it is very easy for an experiment to find no significant effects due to a myriad of reasons; it is more difficult to actually find effects, particularly when using highly sophisticated techniques.”

As for BPA, the authors assess all the scientific evidence, taken together, and evaluate the weight of the evidence for or against the proposition that low-dose exposures of EDCs like BPA can produce adverse effects.  The weight of evidence on BPA, the authors conclude, “clearly shows that low-dose BPA exposure affects development of the mammary gland, mammary histogenesis, gene and protein expression in the land, and the development of mammary cancers.”

The authors analyze the data, the body of published scientific studies, as to several other EDCs as well, including atrazine (a widely used herbicide), dioxin (a byproduct of industrial waste incineration), and perchlorate (a commonly-found industrial waste contaminant).  The findings as to these EDCs are similar to the findings as to BPA.  Low-dose exposures, looking at the weight of the evidence, do produce adverse health effects.

Not all scientists agree with these conclusions.  In itself, this should come as no surprise.  That is why medical and scientific journals increasingly have required that authors disclose when they received funding or support for a particular article.  Bias is always relevant to assess a witness’ credibility in a courtroom and the same is no less so when weighing the views of those engaged in a scientific or policy dispute.

In an article about the EDC study that was published recently in “environment360,” a Yale University on-line publication, it was noted that the American Chemistry Council (ACC) had issued a statement saying that the chemical manufacturers were committing “substantial resources” to better understanding the potential connections between chemical exposure and the endocrine system.  The ACC specifically referred to the work of Michael Kamrin, a toxicologist from Michigan State.

Dr. Kamrin, who has written on the “hypothesis” about low-dose exposures, has proclaimed that such theories are “controversial.”  But who is creating the controversy?

Perhaps the American Council on Science and Health, an industry-funded group whose financial backers include Dow Chemical and other large chemical companies.  Dr. Kamrin is on the Board of Scientific and Policy advisors for that organization.   And, of course, Dow is a major player in the ACC.  For more on Dr. Kamrin’s ties to Dow, see CorpWatch’s paper, “Dow’s Knowledge Factory,” at www.corpwatch.org/article.php?id=10008.

Another critic of Dr. Vandenberg’s study, also quoted in the Yale on-line article, is Lorenz Rhomberg of the Gradient Corporation.  Gradient, based inCambridge,MA, is an environmental consulting company that almost exclusively works for large companies in litigation, including Dow Chemical.  (Gradient does do some government consulting as well.)

What is the take-away?  The ACC and the chemical manufacturers and other industry groups have the ability to devote substantial resources to these issues.    While the public health is an obviously vital interest to protect, Industry also has its interests.  Naturally, industry must protect itself, but from a different kind of exposure.

Industry must protect itself from exposure to avoidable financial costs.  Industry must protect itself against exposure to that which cuts into profits.  Industry must protect itself against exposure to liability.

Recognizing that lower exposures to unnatural chemicals like BPA and atrazine and perchlorate can produce adverse health effects means that federal and state regulatory authorities must act more responsibly in the public’s interest.  This means doing a better job of balancing the needs of companies to make money and the needs of the public to be protected against harmful exposures.