Book Review: True Warnings and False Alarms: Evaluating Fears about the Health Risks of Technology

You open the newspaper, and there you find a dire warning of another newly discovered threat to public health. How seriously should you take it? What are the chances that the warning is well founded? Are there any clues in the story to guide your judgment?

Allan Mazur of Syracuse University's Maxwell School pursues those questions in his book, True Warnings and False Alarms, recently published by RFF Press. He bases his inquiry on 31 cases identified by an earlier researcher, Edward Lawless, as controversial public issues between 1948 and 1971. Mazur's reason for using cases a generation in the past is that, with time and deepening knowledge, judgments on many of them are different from those of 1977, when Lawless's book appeared.

Mazur finds that 18 were valid warnings based on real threats to health. And 13 were not. Looking for a pattern, he classifies these claims by the nature of the sources and circumstances.

"Usually from their earliest moments," he concludes, "valid warnings looked different from those eventually judged mistaken. Alarms more often turned out to be true when their news source was a report of normal scientific research produced at a recognized scientific institution than when the source was a government agent or citizen advocacy group."

Warnings were more likely to be Evaluating Fears about the Health Risks of Technology, 1948-1971 true, he continued, if they appeared in isolation, rather than in an atmosphere already charged with news of other health threats.

But the character and volume of the news coverage seemed to have no relation to the truth of the claim that it conveyed. "Hyped warnings, those for which sources or journalists made unusual efforts to increase news coverage, were no more or less likely to be valid than warnings given routine treatment by the media," he found.

The message contained in Mazur's analysis is not as simple as it might seem at first glance. For example, the claim that DDT was a carcinogen to humans, as well as harmful to a wide range of wildlife, was arguably the most important case in the political development of the modern environmental movement. While Rachel Carson was a highly sophisticated writer with some scientific training, she was not, as Mazur notes, a research scientist working in a scientific institution. She was writing as a journalist and, as he puts it, a citizen. Controversy over health and the environment usually takes place at the outer frontier of scientific research.

Nor, Mazur adds, was her warning an isolated event. It was seized by an audience that remembered the (false) alarms over cranberries treated with allegedly carcinogenic herbicides and the (true) alarm over the drug thalidomide shortly before Silent Spring appeared.

While Mazur offers some general rules for figuring the odds that a new charge is valid, he also conveys the truth that, as any bookie knows, the odds aren't a reliable guide to specific cases. Controversy over health and the environment usually takes place at the outer frontier of scientific research, where even the best informed and most disinterested of observers can be misled.

Policymakers can't avoid acting in haste. But they can keep in mind, if they are wise, that early decisions may be wrong.