An important new study by researchers at the Fred Hutchinson Cancer Research Center in Seattle has found no link between breast cancer risk and exposure to electromagnetic fields (EMFs) from electrical wiring and appliances in the home.

A wide variety of studies have tried to assess the link between a number of cancers and EMFs from many sources, including power lines, appliances, x-ray machines, cell phones and computers, among others. However, the results of these studies have been inconclusive, although certainly not lacking in controversy.

The ionizing radiation given off by sources such as x-rays is known to damage body cells. However, exposure to non-ionizing radiation-such as that given off by computers, cells phones, power lines, and other sources-is still unclear.

The researchers, led by Dr. Scott Davis, compared residential EMF exposure in 813 women who had breast cancer with EMF exposure in 793 healthy women. For the breast cancer patients, they measured magnetic fields in their homes at the time of diagnosis, and evaluated the electrical wiring of the homes that they occupied in the ten years prior to their diagnosis. They also compiled data on the patients' self-reported use of appliances during the study period. Similar measures were then taken from the healthy participants and the results were compared.

Writing in the American Journal of Epidemiology, the researchers concluded that there was no association between such household exposure to EMFs and an increased risk of breast cancer. Their findings confirmed the results of five earlier studies that assessed EMF exposure from electric blankets, and another five studies that estimated EMF exposure from power lines.

However, their findings contradicted three previous studies that did find an association between EMFs and breast cancer risk; one study focused on household EMFs, and the other two assessed exposure from power lines.

Davis' team noted that some researchers suggest that exposure to EMFs may increase breast cancer risk by suppressing a woman's normal production of the sleep hormone melatonin. However, their results did not support such an association.

"Risk did not increase with measured nighttime bedroom magnetic field level, wiring configuration of the home at diagnosis, weighted summary wire codes of all homes occupied 5 and 10 years prior to diagnosis, or reported use of common household appliances, including bed-warming devices," they concluded.

"These data do not support the hypothesis that exposure to residential magnetic fields is associated with an increased risk of developing breast cancer."

SOURCE:
American Journal of Epidemiology, March 1, 2002; 155:446-454