Leukemia rises for kids near power lines Swedes develop data in study of 500,000 people

November 12, 1992|By Boston Globe

In a report to be presented today, Swedish researchers say they found nearly a fourfold increase in leukemia cases among children exposed to the magnetic fields generated by electrical power lines.

Two studies of over 500,000 people, the first to look directly at the impact of high-tension lines on an entire population, provide the strongest evidence yet of a potential danger that has caused growing public concern: the possibility that electrical wiring both inside the home and office and in outside transmission lines could cause various forms of cancer, especially leukemia.

In response to the research, Sweden's National Board for Industrial and Technical Development announced that it would from now on "act on the assumption that there is a connection between exposure to power frequency magnetic fields and cancer, in particular childhood cancer."

"It's tremendously important," says Louis Slesin, editor of Microwave News, a trade newsletter that has taken no position on the controversial studies. "It answers many of the uncertainties and problems of earlier studies . . . This is going to create a completely different attitude in this country about these risks."

The Swedish researchers, who will present their findings at a scientific meeting in San Diego, emphasize that while the new data show a significantly increased risk of cancer for those exposed to the strongest magnetic fields, it is still a very low risk: about one extra case of leukemia, for example, out of every 10,000 exposed people.

While some American researchers express caution about the results, suggesting action should await the findings of more comprehensive studies now under way, Mr. Slesin says the case is convincing enough that "it's time to start protecting people" by trying to minimize exposures to magnetic fields.

One of the new studies looked at all of the children and adults in Sweden -- 500,000 -- who were exposed to magnetic fields in their homes because they lived near high-voltage power transmission lines. The other study looked at 1,662 people, including 250 with leukemia and 261 with brain tumors, who were exposed to magnetic fields on their jobs, such as working on transmission lines.

Any wire that carries electricity, whether it is a high-voltage transmission line, household wiring or wires inside an electric blanket, produces a magnetic field around it.

"This is the first study that's been done on what really worries people most -- high-tension lines," says Nancy Wertheimer, an epidemiologist at the University of Colorado Heath Center in Denver whose 1979 study was the first to suggest a link between magnetic field exposure and cancer.

he strongest link the new studies found was between household exposure of children and the development of childhood leukemia: For those exposed to the highest fields, there was almost a fourfold increase in cases of leukemia. Significantly, it found that the higher the exposure, the higher the increased risk -- the first time such a "dose-response" relationship has been found in magnetic field studies.

The studies found a slightly weaker link between adult exposure to the fields and leukemia: about a threefold increase.

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