Effects of electric and magnetic fields from high-power lines on female urinary excretion of 6-sulfatoxymelatonin

In 1998, the authors studied the effect of residential exposure to electric and magnetic fields from high-power lines on female urinary excretion of 6 -sulfatoxymelatonin (6-OHMS) in the Quebec city, Canada, metropolitan area. A sample of 221 women living near a 735-kV line was compared with 195 wome n the same age living away from any power lines. Participants provided morn ing urine samples on 2 consecutive days and wore a magnetic dosimeter for 3 6 consecutive hours to measure personal magnetic exposure. The indoor elect ric field was assessed by spot measurements. After adjustment for other fac tors associated with low melatonin secretion, such as medication use or lig ht exposure, nighttime concentration of 6-OHMS was similar in the two group s. When either 24-hour or sleep-time exposure to magnetic field or electric field measurements was used, no exposure-effect relation was evident. Howe ver, the trend of decreasing 6-OHMS concentration with age was more pronoun ced for women living near the lines, as was a lower 6-OHMS concentration in women with high body mass index. Chronic residential exposure to magnetic fields from high-power lines may accentuate the decrease in melatonin secre tion observed in some vulnerable subgroups of the population.