Study Reaffirms That Use of Electric Blanket Does Not Increase Risk of Breast Cancer

BUFFALO, N.Y. -- Premenopausal women who sleep under an electric blanket do not significantly increase their risk of developing breast cancer, a study conducted by researchers at the University at Buffalo has shown.

The study will be presented at the Electrical Power Research Institute meeting in Santa Clara, Calif., at 8:45 a.m. on Monday, March 20. It was published in December in the American Journal of Epidemiology.

The current research is a follow-up to an earlier UB study involving postmenopausal women, which also found no increased risk of breast cancer as a result of electric-blanket use.

Scientists have hypothesized that long-term exposure to electromagnetic fields, such as those produced by electric blankets, may affect breast-cancer risk in two ways. One way is indirectly, by inducing changes in the pineal gland, which produces melatonin, a regulator of the hormones prolactin and estrogen, both known to stimulate breast-cell growth. The other is through direct exposure to the breast tissue, which may disrupt cell-membrane function and cell regulation.

In the current study, a team of researchers led by John Vena, Ph.D., UB professor of social and preventive medicine, investigated a possible breast cancer-electric blanket association by comparing electric-blanket use of premenopausal women who were newly diagnosed with breast cancer and a control group of age-matched women who were cancer-free.

A total of 290 cases and 289 controls were interviewed for the study. The women were asked to report their electric-blanket use over the previous 10 years, including frequency of use in season and mode of use -- whether they used it to warm the bed, kept it on continuously through the night, or varied its use.

Results showed that among those who used electric blankets the most, the percentage of women with cancer and without the disease was identical. In both groups, 8.3 percent said they had used a blanket daily in season and continuously throughout the night for the previous 10 years.

"The bottom line is, if there is an effect, it is likely a weak one," Vena stated.

The possible biological mechanism at work remains unclear, he noted. "Some researchers now think that the pineal-melatonin mechanism may only operate for certain types of breast cancer tumors -- those that are estrogen-receptor positive. The next phase of our research will be to look at electric-blanket use and certain types of breast cancer.

"Risk can only be quantified by further studies and more exact measures of exposures," he said.

Also participating in the study were Jo L. Freudenheim, Ph.D.; James R. Marshall, Ph.D.; Rosemary Laughlin, Ph.D.; Mya Swanson, and Saxon Graham, Ph.D., all of the UB Department of Social and Preventive Medicine.