Melatonin and 6-OHMS in high-intensity magnetic fields.

We determined if all-night exposure to 60 Hz magnetic fields at an intensity well within the upper range of occupational exposures (resultant intensity = 127.3 microTesla [muT]) resulted in suppression of melatonin or its major metabolite 6-hydroxymelatonin-sulfate (6-OHMS) in the first-void morning urine of 24 healthy male volunteers. Measures collected after continuous and intermittent magnetic field exposure test conditions were compared to similar measures collected after an equivalent no-exposure control condition. Urinary concentrations of melatonin and 6-OHMS did not differ as a function of type of magnetic field exposure, nor did they differ between field exposure and control conditions. These results demonstrate that the nocturnal secretion and metabolism of melatonin are not altered in humans by field exposure at an intensity over 600 times higher than that typically encountered in the home.