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Text File | 1993-04-08 | 6KB | 115 lines

                                                                                HEALTH, Page 70

Danger Overhead


Two Swedish studies provide the best evidence so far of a link
between electricity and cancer

By CHRISTINE GORMAN -- With reporting by Ulla Plon/Copenhagen


    Can power lines cause cancer? Numerous reports in the
popular press have blared out warnings. Frightened citizens have
abandoned homes located close to high-tension wires; others have
gone to court to keep the lines away. The reason for the
hysteria: a growing number of scientific studies suggest that
the risk of leukemia and other malignancies rises with exposure
to electromagnetic fields, which are generated in varying
degrees by all electrical devices from high-voltage power lines
to hair dryers.

    Until now the studies have been ambiguous. Some have found
an association with brain cancer but not leukemia in children.
Others have detected just the opposite. In addition, the link to
cancer appears stronger when the electromagnetic field is
estimated by researchers and disappears when it is measured by
instruments.

    This fog may finally start to clear because of two studies
done in Sweden. The first, led by epidemiologists Maria
Feychting and Anders Ahlbom of Stockholm's Karolinska Institute,
looked at everyone who lived within 300 m (328 yd.) of a
high-tension line in Sweden from 1960 to '85. Although the
investigators could find no evidence of an increased cancer
threat for adults, they did detect a higher risk of leukemia in
children. The second study, led by Birgitta Floderus of Sweden's
National Institute of Occupational Health, linked on-the-job
exposure to electromagnetic fields and leukemia in workingmen.

    Although the research does not prove cause and effect, it
shows an unmistakable correlation between the degree of exposure
and the risk of childhood leukemia. "From a research point of
view, they add significant information," says Stan Sussman,
manager of electromagnetic-field studies for the Electric Power
Research Institute, a California-based organization funded by
utility companies. "It is becoming more and more likely that
there is something associated with living near high-power lines,
especially for childhood leukemia."

    The results have prompted Sweden's government to consider
whether new regulations are needed. A task force will look at
the concentration of schools and day-care centers close to power
lines. According to Microwave News, a U.S. publication that
covers the field in depth, this is the first time a national
government has acknowledged the link.

    What makes the Karolinska study particularly significant
is the thoroughness of its design. The investigation
encompassed nearly 500,000 people. By restricting their analysis
to high-power transmission lines, the researchers could easily
calculate the field strength for each household studied and be
assured that the lines were the dominant source of
electromagnetic radiation. Since field strength drops off
dramatically with distance and all the houses were in the same
corridor, investigators could also be fairly certain that the
only difference between exposed and unexposed homes was
proximity to the lines, not other environmental factors.

    One of the most telling results was that the cancer risk
grew in proportion to the strength of the electromagnetic
field. Children with constant exposure to the weakest fields,
calculated at less than 1 milligauss (about the same that a
coffee maker generates when it is brewing), had the lowest
incidence of cancer. Those exposed to fields of 2 milligauss
showed a threefold increase in their risk, while children
exposed to 3 milligauss showed a fourfold increase in the risk
of leukemia. Such a clear progression makes it difficult to
argue that factors other than exposure to the electromagnetic
field were responsible for the extra cases of leukemia.

    However, the report does have some weaknesses. Childhood
cancer is so rare that even such a large study was able to
uncover only 142 cases. In the highest exposure groups, the
calculation for leukemia risk was based on as few as seven
cases. In addition, the Swedes found no increase in malignancies
of the brain. "Up to this point the evidence had been stronger
for brain tumors," says David Savitz, an epidemiologist at the
University of North Carolina.

    The second study looked at 1,632 men in central Sweden,
511 of whom had contracted leukemia or brain tumors. Adjusting
for exposures to various other environmental factors, the
researchers concluded that, compared with the other men, more
of the leukemia patients had occupational exposures to
electromagnetic radiation.

    "I think it will take a long time before we have final
proof," Maria Feychting says. But even if the link holds up, she
notes, people should not panic: "The risk for leukemia is very
small -- 1 out of 20,000 children a year." Reacting too hastily
to scientific findings can in itself be hazardous to one's
health. Witness the realization that more people may be exposed
to asbestos during its removal than if it is merely encased. As
for electromagnetic radiation, prudence would suggest that the
ideal location for a new day-care center is not next to city
power lines. For families, it might make more sense simply to
shift a child's bed away from a power line rather than move the
house.