Electric Magnetic Fields Reduce Melatonin

FORT COLLINS, Colo.—Electric magnetic fields reduce melatonin secretion in men regularly exposed to them on the job, according to a new study. The hormone melatonin sets biological clocks, turns on immune systems, fights free radicals and inhibits tumor promoters such as estrogen.

Last year, James Burch, Ph.D., of Colorado State University located here found that electric utility workers exposed to stable magnetic fields had reduced nighttime melatonin secretion. In his latest study of daytime melatonin levels published in the American Journal of Epidemiology [1999 Jul;150(1):27-30], Burch monitored magnetic field and light exposure for three days in 142 male utility workers—from the generating station to the administrative offices. He measured the men's urinary levels of a melatonin breakdown product, 6-OHMS/cr, at the end of their workday at 6 p.m.

Workers exposed to constant levels of magnetic fields emanating from 60 Hz alternating current had reduced nighttime melatonin levels, especially if they worked in the low light of an office.

Although typically produced at much lower levels during the day, daytime melatonin nonetheless activates melatonin receptors and stimulates nighttime melatonin secretion. The workers' "combined reduction of daytime and nocturnal melatonin secretion ... could alter immunologic, oncostatic or antioxidant processes," says Burch.