EMF Not a Breast Cancer Cause

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That's the finding of the recently-completed study "Electromagnetic Fields and Breast Cancer on Long Island: A Case Control Study," published in the American Journal of Epidemiology. The study, part of the ten-year Long Island Breast Cancer Study Project (LIBCSP), is the latest study to come from the project that fails to show a correlation between a perceived environmental risk factor and an actual increased risk for breast cancer. Previous studies discovered no significant association between breast cancer development and exposure to PCBs or to organochlorines found in pesticide. Results from a study on the relation between breast cancer development and proximity to hazardous waste sites is pending.

The LIBCSP study was initiated because rates of breast cancer on Long Island were believed to be significantly higher than those found in the rest of the country. However, even though the Long Island breast cancer initiative has garnered 30 million government dollars to research possible environmental causes, the incidence of breast cancer on Long Island is not much higher than the national average. With LIBCSP director Deborah Winn calling the latest results extremely definitive and reassuring, the study should diminish attention to at least some imaginary or dubious risk factors.

Some scientists have speculated that electric and magnetic fields may cause cancer because of their effect on melatonin. Melatonin is a hormone that the body produces in response to darkness. The body's levels of melatonin decrease in the daytime and increase at night. Melatonin levels are inversely related to estrogen levels. Scientist believe that an increase in the presence of estrogen leads to an increased risk of breast cancer. Thus, if electric and magnetic fields were to decrease the body's melatonin production, they hypothesized, electric and magnetic fields could cause cancer due to an increase in estrogen levels.

Electric and magnetic fields are areas of energy commonly found near basic household appliances, power lines or electrical wiring. Electric fields are induced by voltage difference, and magnetic fields are formed by a flow of current. Both electric and magnetic fields decrease in strength rapidly as distance from the source increases. The force of electric and magnetic fields that surround power lines and household appliances are very low even at close range, though.

The study led by Dr. M. Cristina Leske of Stony Brook University School of Medicine carefully measured the exposure to EMF of 1,161 women in Nassau and Suffolk counties of Long Island. Close to half of the women had breast cancer at the time, while the other half, who have not developed the disease, served as the controls. The researchers used personal interviews and direct EMF measurements in and around the participants' homes to measure EMF exposure. They found that exposure levels were the same for women with and without breast cancer. To make sure exposure time was not a factor in the assessment, all women studied had lived in their place of residence for at least fifteen years. From the results, it is apparent that there is no correlation between residential exposure to EMF and developing breast cancer. Dr. Richard Stevens, the cancer epidemiologist who originally hypothesized the EMF-melatonin-breast cancer relationship, has said of the new research, "It's a good study and the results are quite negative, so that's good evidence that electric fields at the levels you typically find in homes do not increase the risk of breast cancer."

Editor's note: Also see the FactsAndFears piece "EMF: Electric and Magnetic Fears," about overblown EMF health effects claims.