Decisive Word on Magnetic Field-Cancer Link?

A major study has found no link between a childhood cancer and exposure to electromagnetic fields (EMFs) from home wiring. The findings, reported in tomorrow's issue of The New England Journal of Medicine (NEJM), could mark the end of a trail that researchers began following in 1979, with the first suggestions of a link between residential exposure to high EMFs and childhood leukemia.

A team led by epidemiologists Martha Linet of the National Cancer Institute (NCI) and Leslie Robison of the University of Minnesota, Minneapolis, collected data on 638 children with acute lymphoblastic leukemia, a disease that accounts for 80% of all childhood leukemias, and 620 matched controls in nine midwestern and mid-Atlantic states. The NCI team then measured field strengths in each child's bedroom over 24 hours and made spot measurements in the kitchen, the family room, and the room where the mother had slept during her pregnancy.

Comparing the EMF exposure of the cases and controls, the researchers found no association between an increased risk of childhood leukemia and magnetic fields of 0.2 microtesla or more, which were the levels that previous investigators had associated with the cancer. The researchers did find what Linet calls a "hint" of an association in homes with field strengths of 0.4 to 0.499 microtesla. But the numbers of cases and controls at those field strengths were small--just 14 and 5, respectively. Above 0.5 microtesla, the hint vanished. "The results are very clear," says Robison. "They're negative."

The $5 million, 5-year study "will be less easily criticized than previous studies simply because it was conducted so carefully," says Lawrence Fischer, a toxicologist at Michigan State University in East Lansing and chair of the study's advisory group. The results, adds NEJM Deputy Editor Edward Campion in an accompanying editorial, suggest it is time to "stop wasting our research resources" on the EMF-cancer question.

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