Scare Science


March 31, 1993|By JOAN BECK

CHICAGO — Chicago.--Can your cellular phone give you brain cancer? Are electromagnetic fields really dangerous? Must your local school system spend millions of dollars to get rid of asbestos used for insulation decades ago? Should the hole in the ozone scare us into changing our polluting ways? How necessary are all those environmental programs on which the nation spends $140 billion a year?

Questions like these reflect the current and growing concern about the complex relationships between science and public policy, public panic and explosively expensive costs.

The conviction is spreading that a combination of misunderstood science, dogmatic environmentalism, sensationalizing media, gullible public and scientifically naive legislators and regulators may be wasting billions of dollars, causing unnecessary fears and misdirecting the search for the real hazards in our lives.

One indication of that concern is the Heidelberg Appeal, a plea that originated to counter the environmental hype of the Earth Summit in Rio de Janeiro last year. The document warns against decisions made on ''pseudo-scientific arguments or false and non-relevant data'' and has now been signed by more than 2,500 scientists, including several dozen Nobel laureates.

Papers published by the group assert, for example, that there is no proof dioxin causes cancer or birth defects in humans, that the dangers of asbestos when properly used are greatly exaggerated, and that the hazards supposedly posed by the ozone hole and the greenhouse effect are ''largely hypothetical.''

Moreover, in part because of public anxieties about radiation and chemicals, this nation and others are spending billions of dollars on cleanup projects that contribute very little benefit to public health and take money that could be better spent elsewhere.

In other evidence of changing attitudes, Carol M. Browner, new head of the Environmental Protection Agency, is pushing for changes in federal laws that would ease some of the current absolute prohibitions against pesticides and other chemicals that seem to pose only very minimal risk, if any, to humans.

At issue, for example, is a provision in the Federal Food, Drug and Cosmetic Act called the Delaney Clause.

It prohibits any use in food of any additive or pesticide residue in any amount if the substance has been shown to cause cancer in laboratory animals.

But since the provision was enacted in 1958, scientists have learned to measure chemical substances in ever-smaller amounts, easily as little as one part per billion or less -- exposure that could not have been detected earlier and that many scientists now believe is not generally harmful to humans.

Scientific doubts are also growing about the usefulness of tests that dose laboratory animals with extremely large amounts of a test substance to see if it produces tumors. If it does, the theory is that smaller doses may do the same in at least some human beings and that the substance is a carcinogen.

But the high dosage itself may be what causes the cancer, according to Bruce Ames, professor of biochemistry and molecular biology at the University of California at Berkeley, a world-known authority on detecting carcinogens. The overdosing can cause damage to the tissues that leads to chronic cell division -- and that, not the test substance itself, is a major risk factor for cancer, he says.

It's easy enough to say that decisions about health and environmental concerns should be based on sound, scientific evidence that meets commonly accepted standards. But it's not that simple.

Scientific evidence may take years to accumulate -- and may still be inadequate. It's impossible to expose large numbers of people to possible carcinogens or other harmful substances to determine their precise dangers. Animal data are increasingly being questioned. Computer models and test-tube experiments are even less definitive.

Much of what we consider scientific evidence is based on links and associations -- not clear-cut cause-and-effect relationships. That can lead to misconceptions and errors, as Dr. Ames has noted. ''The number of storks in Germany has been decreasing for years,'' he has pointed out. ''At the same time, the German birth rate also has been decreasing. Solid evidence that storks bring babies!''

Human beings may react differently to environmental factors, depending on their genetic makeup, age, dosage, lifestyle and other variables. What they believe is also influenced by their emotions and a need to find a reason or something to blame for an illness. Some Vietnam veterans, for example, are still convinced, contrary to numerous studies, that they were harmed by Agent Orange. And a man set off a nationwide storm by charging on a TV talk show, without evidence, that his wife's brain cancer death was caused by a cellular phone.

This spring, the Supreme Court will rule on what standards of scientific evidence are permissible in federal court and what credentials expert witnesses should have.

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