MILLER: Understanding risk

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COMMENTARY:

Americans are very risk-conscious. We buy muscular, crash-resistant SUVs and spend billions on overpriced (and overrated) organic foods. Often, we learn about risks and remedies by relying on the media to interpret medical research and other data that purport to tell what is bad (or good) for us.

The incessant dire warnings - about trace chemicals in the water supply, carbon monoxide in our homes, pesticides used in agriculture and even plasticizers in rubber duckies - might make the world may seem full of quotidian lethal hazards, but many of these alarms are completely bogus while most of the others represent only de minimis, or negligible, risks.

Moreover, the attention paid to them and the wrong-headed (and often very costly) actions taken to prevent or ameliorate them can themselves be harmful by distracting attention from far more significant risks and by squandering societal resources.

Consider synthetic trans fatty acids in foods. These partially hydrogenated oils came into widespread use as a way to decrease the consumption of saturated fats, which are known to raise levels of "bad," or LDL, cholesterol in the blood. In the 1980s, trans fats were touted as a "healthier" kind of fat to consume.

But later research showed trans fats weren't better than saturated fats after all - and the fearmongers sprang back into action. Now trans fats have been condemned as the most toxic ingredients in the American diet (also a gross exaggeration) and have been banished from New York City restaurants - but only after many people had been opting for trans fat-containing spreads for a couple of decades.

Another example of misperception of risk is acrylamide, a useful industrial compound formed naturally in high-carbohydrate-containing foods cooked at high temperatures, such as in frying or broiling. It has thus been part of the human diet since humans learned that cooked foods taste better (and are often safer) than raw ones. Yet because we only learned of acrylamide's existence in foods recently, and because very large amounts fed to animals cause cancer, there have been calls to require warning labels on fried foods and other products - even though acrylamide in food has never been shown to harm human health.

Yet another example of a poorly substantiated health threat is the current scare about bisphenol A (BPA) - a chemical used to make certain plastics clear and shatterproof. Again, because animals fed huge doses of the chemical experienced ill effects, and because only minuscule amounts can leach into the contents of plastic cups and bottles when they are heated, warnings about an effect on infants and children (guaranteed to have the most potent effect on parents) have been trumpeted in the media.

But these risks aren't real - or to be more accurate, they haven't been substantiated. If we followed through by banning all the chemicals we read about that supposedly cause (pick one) cancer, birth defects, low sperm counts, Alzheimer's disease, autism, etc., we'd have to ban most of the chemicals in the world - including "natural" ones.

Unfortunately, the scares are real attention-grabbers; they sell papers and attract our attention on TV spots and Internet blogs. And many journalists and editors - to say nothing of politicians - seem not to care whether the science supports the hype. The scares get repeated again and again and eventually become "popular wisdom."

How can we know what we should worry about? There is a remarkable new interactive Web source that helps consumers to answer that question - to understand what poses significant health risks, and what does not. The New York-based American Council on Science and Health (ACSH) has produced and manages what they call a "Riskometer" (www.Riskometer.org), which allows visitors to compare health risks. It informs us that exposure to cigarette smoking is far and away the leading cause of cancer death: In 2002 the odds of dying from smoking were 1 in 771. (The "odds of dying" is defined as the number of people expected to produce one death from a particular cause.) The odds of dying from obesity or from unintentional injuries (including traffic accidents, falls, and others) are each about 1 in 2,800. Far less likely is death from exposure to the dry cleaning fluid perchloroethylene (PERC) or from arsenic in water (about 1 in 6,000,000, roughly the same as dying from an insect bite). Despite this infinitesimal risk, laws were passed restricting the use of PERC - because "everyone knows" it's a serious health risk.

Such misunderstandings lead to the squandering of societal resources: The Environmental Protection Agency's "land disposal restrictions" when toxins are present impose annual costs of about $205.5 million, in order to avoid 0.22 cases of cancer annually from groundwater contamination and 0.037 cases from air pollution - that is, about one case of cancer every four years - and $20 million from property damage.

The ACSH Riskometer offers actual data which show that many of the hyped "threats" that we hear and read about daily occur very far down on the list. The media's "pseudo-scare mode" is a disservice to its viewers and listeners because people have only so much time to pay attention to health issues, and if most stories focus attention on negligible threats, greater risks that individuals may be able to control get short shrift.

The bottom line: Be skeptical, be informed, consult the Riskometer.

Henry Miller, a physician and molecular biologist, is a fellow at Stanford University's Hoover Institution. He was at the National Institutes of Health and Food and Drug Administration from 1977 to 1994. His most recent book is "The Frankenfood Myth."