Do EMFs pose breast cancer risk?

Women employed in the electrical trades run a 38 percent greater risk of dying from breast cancer than other working women, says a new study These findings will most likely fuel the debate about whether exposure to low-frequency electromagnetic fields (EMFs) boosts the risk of developing certain malignancies, such as leukemia, brain cancer, and breast cancer.

A look at previous research reveals a raft of conflicting results. One investigation showed that men in electrical occupations had more than six times the breast cancer risk of men in the general population (SN: 9/28/91, p. 202). Yet other scientists failed to demonstrate any elevated risk for men. Epidemiologists searching for a link between exposure to EMFs and breast cancer in women came up empty-handed -- until now, that is.

Epidemiologist Dana P Loomis of the University of North Carolina in Chapel Hill and his colleagues began their study by combing through U.S. death records for 1985 through 1989. Among women who had been employed as electrical workers, the team identified 68 who had died of breast cancer and 199 who had died of other causes. Included in the sample were electrical engineers, electricians, telephone repairers, and power-line workers. The researchers then turned to a control group -- women who had been employed outside the home but not in the electrical trades. They found 27,814 women who had died of breast cancer and 110,750 who had died of other causes.

Statistical analysis indicated that women who work in electrical occupations face a greater threat of death from breast cancer than other employed women. People in such jobs sustain much higher levels of exposure to EMFs than the average person, Loomis notes.

Certain groups had substantially higher risks than their peers. For example, women who were electrical engineers had a 73 percent greater risk of dying from breast cancer. For telephone installers, repairwomen, and line workers, that heightened risk jumped to 200 percent.

The research team did not find a higher risk of breast cancer death among women in seven occupations that may also involve elevated exposure to EMFs. For example, women who worked as telephone operators, data keyers, or computer operators did not appear to show the same surge in mortality rates. The team describes its results in the June 15 Journal of the National Cancer Institute.

Epidemiologist Dimitrios Trichopoulos of the Harvard School of Public Health in Boston notes that the researchers didn't measure electromagnetic exposure directly Instead, they relied on each woman's stated occupation as a crude marker of exposure. "The authors did a very good job in the analysis," Trichopoulos told Science News. "But it's really a weak database." Trichopoulos wrote an editorial that accompanied the article.

Even critics such as Trichopoulos don't discount the notion that EMFs may increase the risk of cancer. Here's why

The new findings fit with a theory that exposure to such fields can reduce the pineal gland's nighttime production of an anticancer hormone called melatonin (SN: 7/3/93, p.10). Reduced concentrations of melatonin in the blood spur the growth of breast cancer cells, suggests Richard G. Stevens of the Pacific Northwest Laboratory in Richland, Wash.

Stevens, Loomis, and other researchers believe that further research must address the question of whether EMFs increase the risk of breast cancer for all women, not just those in the electrical trades. Electromagnetic fields are generated by wiring and such household appliances as microwave ovens, televisions, and hair dryers.

"At this point, there's nothing [definite] to be said about the risk to people," Stevens cautions. However, he believes that ongoing studies of EMF exposure and breast cancer will yield some answers soon.