Melatonin metabolite levels in workers exposed to 60-Hz magnetic fields: work in substations and with 3-phase conductors

J Occup Environ Med. 2000 Feb;42(2):136-42. doi: 10.1097/00043764-200002000-00006.


Melatonin suppression by 50/60-Hz magnetic fields represents a plausible biological mechanism for explaining increased health risks in workers. Personal exposure to magnetic fields and ambient light, and excretion of the melatonin metabolite 6-hydroxymelatonin sulfate (6-OHMS), were measured over 3 consecutive workdays in electric utility workers. There was a magnetic field-dependent reduction in adjusted mean nocturnal and post-work 6-OHMS levels among men working more than 2 hours per day in substation and 3-phase environments and no effect among those working 2 hours or less. No changes were observed among men working in 1-phase environments. The results suggest that circular or elliptical magnetic field polarization, or another factor linked to substations and 3-phase electricity, is associated with magnetic field induced melatonin suppression in humans.

Publication types

  • Clinical Trial
  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Chromatography, High Pressure Liquid
  • Circadian Rhythm
  • Electricity
  • Electromagnetic Fields / adverse effects*
  • Environmental Monitoring*
  • Humans
  • Male
  • Melatonin / analogs & derivatives*
  • Melatonin / metabolism
  • Melatonin / radiation effects*
  • Melatonin / urine
  • Middle Aged
  • Occupational Exposure / adverse effects*
  • Power Plants
  • Radiation Dosage
  • Risk Assessment
  • Workplace


  • Melatonin
  • 6-hydroxymelatonin