If low-level exposure to pollutants is good for us, what does that mean for regulations?


By Kevin Elliott
Associate Professor, University of South Carolina

Could low-level exposure to polluting chemicals be good for us? Some researchers claim that a phenomenon called hormesis – beneficial effects caused by low doses of normally toxic substances – could indeed be widespread.

Hormesis is an intriguing phenomenon with potential regulatory implications. It also illustrates a problem that is widespread throughout the environmental sciences – special interests seeking to influence research for their benefit. The hormesis case provides yet another example of these influences and a new opportunity to think about how to make policy-relevant research responsive to a wider range of societal priorities.

Edward Calabrese, a professor of toxicology at the University of Massachusetts, Amherst, argues that carcinogens typically display hormetic effects. Rather than assuming that carcinogens are harmful at all dose levels as regulatory agencies currently do, he thinks that regulators should be treating carcinogens like other chemicals and assuming that there are thresholds below which they cease to have harmful effects. As Calabrese notes, these changes would have significant economic benefits for regulated industries.

It is clear that some substances do have widely varying effects at different dose levels. Alcohol, for example, appears to increase human mortality when consumed in large quantities, but it decreases mortality rates (below those of teetotalers!) when consumed in moderation. It is less clear how often polluting substances display the same combination of beneficial effects at low doses and harmful effects at higher doses.

Based on a database of previous toxicology studies, Calabrese claims that toxic chemicals generally display hormesis, but other scientists are skeptical. Their worries are exacerbated by the fact that Calabrese has received funding from a number of groups with an interest in easing chemical regulations, including the U.S. Air Force, Exxon Mobil, and the Texas Institute for the Advancement of Chemical Technology. It is not clear that Calabrese has deliberately allowed the concerns of these funders to influence his work. Nevertheless, research on hormesis – like most areas of policy-relevant science – incorporates a host of judgments that can be influenced either consciously or unconsciously by the priorities of scientists and the contexts in which they work.

In my recent book, Is a Little Pollution Good for You? Incorporating Societal Values in Environmental Research, I highlight a wide range of judgments that contribute to differing conclusions about hormesis by various researchers. For example, Calabrese cites cadmium as an example of a carcinogenic chemical that displays beneficial effects at low doses. However, other scientists argue that even if cadmium decreases the rates of some cancers, it also displays endocrine disrupting effects that may increase the rates of other cancers. Paul Mushak, a critic of the hormesis hypothesis, also challenges Calabrese for appealing to a few dozen studies to support the claim that lead displays hormetic properties. Mushak insists that these are but a small subset of thousands of studies, many of which indicate that lead has neurotoxic effects even at very low doses.

As in the hormesis case, the environmental sciences are often permeated by socially significant choices about how best to analyze and communicate available data. Therefore, we should be concerned about who is funding research and influencing how these choices are made. Some recent statistics indicate that about 80 percent of U.S. R&D money comes from either industry or the military. This does not mean that these “deep pockets” entirely dominate scientific research, but it may mean that the production and interpretation of research does not reflect society’s full range of priorities as well as it should.

I suggest three strategies for making the environmental sciences more responsive to a range of societal priorities other than those of deep pockets.

First, we need to encourage more government funding of research from agencies such as the National Science Foundation (NSF) or the National Institutes of Health (NIH). While research based on NSF or NIH funding is not value-free, it is less likely to reflect the values of individual interest groups than research funded by private sources.

Second, we should promote deliberative forums in which a range of scientists (and, when appropriate, other stakeholders) can highlight important judgments associated with particular areas of research and consider how best to address them.

Third, we should work with the scientific community to develop guidelines for disseminating information about controversial or debated areas of research to the public. Ideally, this would help scientists highlight crucial judgments and facilitate better scrutiny by a range of citizens.

A series of reports published by the National Academy of Sciences on the effects of ionizing radiation provides an example of how these strategies could alleviate the influences of deep pockets in the hormesis case. These reports, produced by a diverse body of scientists, provide citizens and policy makers with a reliable source of information to counter the claims of interest groups who insist that low-level exposure to ionizing radiation is beneficial. Forming a similar panel in the hormesis case would help concerned citizens and policy makers who read conflicting opinions in venues like the Wall Street Journal or Fortune and are left wondering whom to trust and what to think.

Strategies like this are not a panacea, but they go some way toward promoting a body of environmental science worthy of our society’s democratic ideals. 

Kevin C. Elliott is Director of the Carolina Leadership Initiative and an Associate Professor in the Department of Philosophy at University of South Carolina, http://people.cas.sc.edu/elliotkc/ He is the author of Is a Little Pollution Good for You? Incorporating Societal Values in Environmental Research .


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