Mystery -- And Maybe Danger -- in the Air

By Philip Elmer-DeWitt

Can electricity cause cancer? In a society that literally runs on electric power, the very idea seems preposterous. But for more than a decade, a growing band of scientists and journalists has pointed to studies that seem to link exposure to electromagnetic fields with increased risk of leukemia and other malignancies. The implications are unsettling, to say the least, since everyone comes into contact with such fields, which are generated by everything electrical, from power lines and antennas to personal computers and microwave ovens. Because evidence on the subject is inconclusive and often contradictory, it has been hard to decide whether concern about the health effects of electricity is legitimate -- or the worst kind of paranoia.

Now the alarmists have gained some qualified support from the Environmental Protection Agency. In the executive summary of a new scientific review, released in draft form late last week, the EPA has put forward what amounts to the most serious government warning to date. The agency tentatively concludes that scientific evidence "suggests a causal link" between extremely low- frequency electromagnetic fields -- those having very long wavelengths -- and leukemia, lymphoma and brain cancer. While the report falls short of classifying ELF fields as probable carcinogens, it does identify the common 60-hertz magnetic field as "a possible, but not proven, cause of cancer in humans."

The report is no reason to panic -- or even to lose sleep. If there is a cancer risk, it is a small one. The evidence is still so controversial that the draft stirred a great deal of debate within the Bush Administration, and the EPA released it over strong objections from the Pentagon and the White House. But now no one can deny that the issue must be taken seriously and that much more research is needed.

At the heart of the debate is a simple and well-understood physical phenomenon: when an electric current passes through a wire, it generates an electromagnetic field that exerts forces on surrounding objects. For many years, scientists dismissed any suggestion that such forces might be harmful, primarily because they are so extraordinarily weak. The ELF magnetic field generated by a video terminal measures only a few milligauss, or about one- hundredth the strength of the earth's own magnetic field. The electric fields surrounding a power line can be as high as 10 kilovolts per meter, but the corresponding field induced in human cells will be only about 1 millivolt per meter. This is far less than the electric fields that the cells themselves generate.

How could such minuscule forces pose a health danger? The consensus used to be that they could not, and for decades scientists concentrated on more powerful kinds of radiation, like X rays, that pack sufficient wallop to knock electrons out of the molecules that make up the human body. Such "ionizing" radiations have been clearly linked to increased cancer risks, and there are regulations to control emissions.

Doubts about weak, so-called nonionizing radiation began to grow in 1979, when a study of cancer rates among Colorado schoolchildren found that those who lived near power lines had two to three times as great a chance of developing cancer. The link seemed so unlikely that when power companies paid to have the original study replicated, most scientists expected the results to be negative. In fact, the subsequent study supported the original findings, which have since been buttressed by reports showing increased cancer rates among electrical workers.

While many experts still express skepticism, there has been a definite shift of attitude in the scientific community about the possible health effects of electromagnetic fields, as a recent series in Science magazine made clear. "In the 1970's ((the link)) seemed absurd," the articles concluded. "Now it's a legitimate open question."

But epidemiological studies, which find statistical associations between sets of data, do not prove cause and effect. Though there is a body of laboratory work showing that exposure to ELF fields can have biological effects on animal tissues, a mechanism by which those effects could lead to cancerous growths has never been found.

The Pentagon is far from persuaded. In a blistering 33-page critique of the EPA report, Air Force scientists charge its authors with having "biased the entire document" toward proving a link. "Our reviewers are convinced that there is no suggestion that ((electromagnetic fields)) present in the environment induce or promote cancer," the Air Force concludes. "It is astonishing that the EPA would lend its imprimatur on this report." The Pentagon's concern is understandable. There is hardly a unit of the modern military that does not depend on the heavy use of some kind of electronic ! equipment, from huge ground-based radar towers to the defense systems built into every warship and plane.

Several Administration officials are also skeptical about the EPA's conclusions. Last June draft language classifying ELF fields as a "probable carcinogen" was deleted from an earlier version of the EPA report after it was reviewed by the White House. At the time, the EPA denied that it was pressured into dropping the offending words.

This time it is clear that the White House is hoping for a more balanced presentation of the evidence. The draft's release was reportedly delayed at the request of Allan Bromley, President Bush's science adviser, who asked that it be reviewed by another scientific panel and prefaced with a statement that qualifies the conclusions. In an interview with TIME, Bromley made it plain that he believes the EPA's findings of a "positive association" between electromagnetic fields and childhood cancer are "quite incorrect." "There's no scientific basis for that statement at all," says Bromley. "What we're doing is unnecessarily frightening millions of parents."

The stakes are high. This week a study in the American Journal of Industrial Medicine reports a steep rise in brain-cancer rates over the past dozen years. If the increased incidence of such cancers could be linked to electromagnetism in the home or workplace, liability suits could clog the courts. Property values near power lines and electric substations are plummeting. If the utilities have to bury or reroute those systems, the cost of doing business could take a sharp jump.

How serious is the risk from electromagnetic fields? Compared with some of the other dangers people take for granted -- driving a car on New Year's Eve, for example -- the odds of being afflicted with some of the cancers associated with electromagnetism are rather small. Brain cancer is a rare disease. Only 3.1 cases per 100,000 people were reported in 1986. In the most worrisome studies, the risk of developing such a cancer appears to double or triple because of ELF fields. By contrast, the risk of lung cancer for a chain smoker is 20 times as great as it is for the public at large.

But there is a difference between a smoker who ignores the Surgeon General's warning and someone who develops cancer passively just by being born into the electronic age. People live near power lines and work with their noses in computer display screens because those things are part and parcel of the ( times. Everyone deserves at the very least a rough sense of what danger such exposure brings.

More study is essential. The bulk of the research being conducted on the health effects of electromagnetic radiation -- at a cost of some $10 million a year -- is paid for by the Department of Energy and the Electric Power Research Institute, neither of which is a disinterested party. The EPA used to conduct its own studies, but funding for its research was cut off by the Reagan Administration. Perhaps the best candidate for new funding would be the National Institutes for Health. The research should examine not only the effects of ELF fields but also those of less-studied radiation having shorter wavelengths, such as radio and TV waves.

Meanwhile, ordinary citizens can exercise what is called prudent avoidance -- doing relatively easy things to minimize a possible risk. This is not the time to sell, tear apart or rebuild a home. But it might make sense to shift a child's bed away from the electric line that brings power to the house. Or to move the telephone answering machine away from the head of the bed. It isn't hard to take a step back from the TV or computer screen, and it could make a big difference in the long run.

CHART: WHAT TO WATCH OUT FOR

CREDIT: TIME Chart

CAPTION: Probably no individual has collected more information about extremely low-frequency fields -- or done more to sound the alarm about the dangers they may pose -- than Louis Slesin, editor of a newsletter called Microwave News. Here is his ranking of the worst hazards -- and some advice:

1. High-tension electric transmission lines. Strung along high towers, these lines carry large amounts of electricity over long distances. Homes, schools and playgrounds should not be built anywhere near them.

2. Electric distribution lines. The kind that carry current down local streets, they generate fields less powerful than those from transmission lines. But distribution line are much closer to most homes. Utilities can sometimes bury or relocate the lines.

3. Electric blankets. They lie right on top of the body for hours at a time. It's a good idea to warm the bed and then unplug the blanket before going to sleep -- or better still, get a quilt instead.

4. Video-display terminals. People spend whole workdays close to computer screens. The should stay 75 cm (30 in.) from the front and 90cm (3 ft.) from the sides and back. The same rule applies to TVs.

5. Bedside appliances. Electric clocks and fans usually run continuously. They should be kept at least 75 cm (30 in.) from the head.

6. Other appliances. Shavers, hair dryers, can openers and microwave ovens all generate powerful fields, and people should be careful to use them for only short periods of time.

With reporting by Dick Thompson/Washington