A single nocturnal exposure to 2-7 millitesla static magnetic fields does not inhibit the excretion of 6-sulfatoxymelatonin in healthy young men

The present study sought to evaluate possible acute effects on 6-sulfatoxym elatonin (aMT6s) excretion, a surrogate for melatonin levels in blood, in v olunteers exposed to static magnetic fields with flux densities representat ive for workers in light metal reduction plants and operators of medical MR T in hospitals. Eleven healthy male volunteers (23-43 years) participated. Urine samples were collected for two consecutive 24 h periods from 22:00 ho urs day 1 (exposure day) through day 2 (day after exposure) and then for 24 h from 07:00 hours on day 7 (control day). On the day of exposure the subj ects slept in the MRI room from 22:00 hours until 07:00 hours next morning, thus receiving a 9 h exposure to the magnetic field (2-7 mT). On the day a fter exposure and on the control day, they slept at home and otherwise perf ormed their ordinary daily activities. Total daily urine production was col lected in four parts: 22:00-07:00 hours, 07:00-11:00 hours, 11:00-18:00 hou rs, 18:00-22:00 hours, and the volume for each interval was measured and re corded. Samples were transferred to coded bottles and frozen for later RIA analysis of aMT6s. Pairs of values of mean hourly aMT6s excretion, both diu rnal and for the four daily intervals, were compared using two-sided Wilcox on signed ranks test. The day of exposure and the day after exposure were n ot significantly different from the control day, either for the total diurn al secretion or the interval data. In summary, the study shows no associati on between a single nocturnal exposure to a static magnetic field of streng th 2-7 mT and excretion of aMT6s in urine. Bioelectromagnetics 22:1-6, 2001 . (C) 2001 Wiley-Liss, Inc.