The Force Is With You

AS ENVIRONMENTAL SCARES GO, electromagnetic fields have it all. They are silent and invisible. Few nonscientists know what they are, much less where they come from. Most alarming, they are ubiquitous: they exist anywhere electrons zip through transmission lines or the innards of appliances or snuggly electric blankets, so avoiding them is plain impossible. Over the years, vari- ous studies have linked electromagnetic fields (EMFs) to cancer. But last week, after three years of examining more than 500 studies, a 16-member panel of the Nation- al Research Council concluded in a report issued on Halloween that EMFs are not so scary after all. ""The current body of evidence,'' says the 314-page report, ""does not show that exposure to these fields presents a human-health hazard.''

The EMF scare was triggered by the most potent combination in environmental health: children and cancer. In 1979, epidemiologists found that children living near high-current power lines in Denver got leukemia at 1.5 times the expected rate. Instead of an incidence of 1 in 30,000, the rate was 1 in 20,000. Follow-up studies confirmed the link to power lines. But these studies are hobbled by a huge paradox. Because it is nearly impossible to continuously monitor actual EMFs inside thousands of houses, much less reconstruct the past exposure of a child who developed leukemia, the studies all use a stand-in for EMF exposure. The stand-in is called a wire-code rating; it reflects a home's distance from a power line and the size of wires close by. The higher a house's rating, virtually all the studies find, the greater the chance that a child in that house will get leukemia. But when researchers actually measure EMFs, they find that fields are no higher in homes with leukemia cases than in homes without. In other words, there is no relationship between the strength of the field and the incidence of leukemia.

Then how can there be a link between wires outside a window and leukemia? Finding the answer, said the NRC (the operating arm of the National Academy of Sciences), should be an urgent priority for future research. Perhaps the fields from the wires cause cancer only ""in concert with other environmental agents,'' suggests Richard Luben, a member of the panel and a biochemist at the University of California, Riverside; absent those agents, EMFs will not promote cancer. Or perhaps the wire-code ratings act as proxies not for magnetic fields but for ""the true risk factor,'' as the report puts it. High ratings are characteristic of older homes, homes in dense developments and homes in high-traffic areas. Perhaps one of these is the real cancer culprit.

Apart from the puzzling leukemia connection, EMFs pose little risk, finds the NRC. Magnetic fields typical of those in homes do not seem to harm DNA, fetuses, the reproductive system or the brain. Hearing this, electric utilities could finally exhale. They are already spending tens of millions of dollars on EMF research. If the EMF verdict had been more damning, utilities would have faced pressure to bury transmission lines. Cost: more than $200 billion.

But EMFs have not beaten the rap completely. The NRC panel found an absence of proof, not proof of absence (of risk). As H. Keith Florig of Carnegie Mellon University points out, ""There is no conclusive evidence that there isn't a problem.'' One finding in particular cries out for more study, even the NRC says. Although in almost every experiment only EMFs hundreds or thousands of times higher than those in a home harmed cells, there is one exception. Everyday levels of EMFs, find researchers led by Robert Liburdy of Lawrence Berkeley Laboratory, suppress cells'production of melatonin. In lab tests, this hormone slows the growth of breast cells on their way to becoming cancerous. And lab animals treated with carcinogens have a greater risk of breast cancer when later exposed to an intense magnetic field..

EMFs are, at most, a small hazard. Those still worried can minimize the risk even further. Replace an old electric blanket, which generates higher fields than new models, with a comforter. Stand back from appliances: moving 12 inches away from a can opener or hair dryer, rather than six inches, cuts the field strength by 75 percent.

Comments