Science, Common Sense and Our Public Fears : Risk assessment: Incorrect use of facts, as in the malathion controversy, leads to faulty social policy. Scientists must help return balance to the debate.

John A. Moore is president of the Institute for Evaluating Health Risks in Irvine, Calif . This article is adapted from a speech delivered to the Health Effects Institute

Risk assessment is a tool used by scientists to evaluate technical data. Proper use of the tool requires scientific knowledge. Since its broad adoption by the Environmental Protection Agency in the mid-1980s, risk assessment in the hands of others unfortunately has become a toy to create uninformed social policy out of rhetoric rather than scientific reason.

A recent example is the series of lawsuits in Los Angeles filed by community leaders to halt malathion spraying over urban areas. Justifiable as a response to constituent fears, these suits are strongly indicative of a much deeper problem: an overriding lack of comprehension of the great difference between what science reasonably concludes is harmful and what the public perceives is harmful. Based on this ignorance, political and community leaders, either with sincere concern or to work a specific political agenda, use risk assessment statistics in a most unscientific way. This unenlightened posturing leads to faulty social policy. Politicians are not, however, the only ones at fault. An aloof scientific community may share the blame.

"Mainstream science" must participate actively in this arena. We readily hear from the extremes at either end of the scientific spectrum. Yet, 90% of scientists know that there is a middle ground, but the public never hears their view.

The fact that mainstream science chooses to stay out of the fray has led to serious confusion over the difference between a "hazard" and a "risk." What the public needs to understand is that today, with astonishing sophistication and accuracy, science can measure traces of chemicals in parts as infinitesimal as one-trillionth. Such measurements, when they pertain to a chemical that may present a health hazard, give rise to an understandable progression of assumptions that go something like this: Chemical A has been found in the ground water of Anytown, U.S.A; Chemical A is on a "bad" list of chemicals, and, therefore, the ground water in Anytown poses a health risk.

We do this with ground water, we do this with apples, and we do this with malathion. I am not here to assess the current malathion levels being used by the state of California, nor am I here to discuss the wisdom or lack of it in the spraying. What I urge is this consideration: It is not the chemical that poses the risk, it is the dose.

The most obvious application of that rule can be found in every medicine cabinet, where aspirin, a potential hazard, is kept. Take one or two aspirin, and your headache goes away. Take two bottles and a significant health risk results. It is the dose that creates that risk.

That is the lesson we must learn from the current malathion controversy. In the most recent lawsuit, brought by L.A. Councilman Joel Wachs, Superior Court Judge John Zebrowski ruled that there is more danger from the lead in the dirt in Los Angeles than there is from the level of lead found in the bait used in the malathion spraying. He said that we would be at greater risk if we all threw dirt at one another.

The lesson for all of us is the court's judgment showing an entirely different conclusion once scientific facts are understood. What helped Judge Zebrowski reach his conclusion was science and fact (and perhaps some common sense).

Invaluable and important scientific information on which to assess public policies makes a difference. Yet the scientific community, which often sees itself apart from the rest of the public, is often missing when most needed.

To overcome this, science must recognize two things. First, scientists must accept the fact that the public has a vital and valid role in the debate over whether a risk exists and what to do about it.

Second, if the public cares as deeply as it obviously does about health risk assessment, we in science must respond with understandable, effective communication of the best information that we can offer. We have to include the public in the debates that are of concern, not because we stand apart from the public, but because we are the public, too.

With more effective participation from mainstream science, the public and its leaders will create informed social policy that will indeed reduce harm, and most important, eliminate the panic and fear in which too many of us now live.

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