ROANOKE TIMES
Copyright (c) 1997, Roanoke Times
DATE: Tuesday, January 7, 1997 TAG: 9701070114
SECTION: EDITORIAL PAGE: A5 EDITION: METRO
SOURCE: CHARLES F. STEVENS
FOR ALMOST 20 years, people have been worrying about whether the electric and magnetic fields in their homes and workplaces can cause cancer, reproductive problems or other illnesses.
Because these fields are invisible, pass through walls and cannot be avoided, the possibility that they might cause disease has been especially frightening. Inconclusive scientific results and sometimes emotional news coverage have added to the confusion.
I just finished chairing an independent committee of nonpartisan experts, brought together to examine all of the scientific information regarding electric and magnetic fields. Our conclusion: There is no convincing evidence that residential exposures to these fields are a threat to health. While research should continue in certain areas, the scientific evidence gives no cause to worry about exposures to electric appliances or power lines.
The news stories and editorials generated by our report have tended to fall into two camps. Some stories emphasized the lack of evidence for any health effects. They noted, for example, that the currents generated in the body by residential electric and magnetic fields are much smaller than the currents generated naturally by nerves and muscles.
Other stories emphasized the remaining uncertainties. They pointed to the questions that still surround electric and magnetic fields, and cited the need for further research.
In fact, both views are accurate.
If people start with the idea that electric and magnetic fields are hazardous, and then ask science to prove otherwise, they are asking the impossible. Scientists never can prove that something in the environment is safe; there always will be a chance that a new experiment might uncover some danger missed earlier.
What can be said is that many good scientists have been trying hard for a decade and a half to uncover adverse health effects from these fields, and none has turned up. In fact, few suspected environmental hazards have been examined as extensively.
The remaining worry about these fields - and the reason some people still believe they represent a hazard - centers on a puzzling link between electric power lines and childhood leukemia. Studies conducted since 1979 have shown that children who live close to electric power lines have a slightly increased risk of developing leukemia. But this observation does not mean that the power lines are causing leukemia. Indeed, when researchers measured the actual magnetic and electric fields inside homes located near large power lines, they failed to find the same association between measured fields and leukemia.
Then what accounts for the increased incidence of leukemia? We just don't know. Homes near large power lines tend to be older, closer together and situated near pollutant-generating traffic. Could a pollutant associated with living near a busy street be the cause? We need more research to identify the cause of these additional cases of leukemia.
The increased risk of leukemia is very small. That's no consolation to a family affected by the disease, but it explains why the causes of the increased risk have been so hard to track down. It also emphasizes the need for thoroughness and rigor in ongoing research designed to explain the power line-leukemia connection.
The case of electric and magnetic fields illustrates the great difficulty - and cost - of trying to identify weak environmental hazards.
Scientists have worked for years to evaluate the possible health effects of these fields. They have carried out multiple epidemiological studies, much animal research and many laboratory investigations.
Our committee evaluated more than 500 studies, and at the end all we can say is that the evidence doesn't point to these fields being a health risk.
Doing research on possible environmental health risks is a slow and expensive process. But this research will remain essential as public concerns continue to focus on environmental causes of disease.
Charles F. Stevens is a neurobiologist with the Salk Institute in La Jolla, Calif.
National Academy of Science
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