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Multi‐night exposure to 60 Hz magnetic fields: Effects on melatonin and its enzymatic metabolite
Author(s) -
Graham Charles,
Cook Mary R.,
Sastre Antonio,
Riffle Donald W.,
Gerkovich Mary M.
Publication year - 2000
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1034/j.1600-079x.2000.280101.x
Subject(s) - melatonin , metabolite , morning , circadian rhythm , nocturnal , urinary system , urine , endocrinology , medicine , zoology , chemistry , physiology , biology
Magnetic field‐induced suppression of nocturnal melatonin in humans has been reported in occupational and residential studies, but not in laboratory‐based exposure studies. The present study examined whether this contrasting pattern of results might be related to associated differences in exposure duration or to field‐induced measurement instability over time. Thirty healthy young men were evaluated using a randomized, double‐blind test protocol. Statistical analysis indicated that 4 consecutive nights of exposure to power‐frequency magnetic fields at occupational intensity (resultant flux density=28.3 microtesla, μT, [283 milligauss, mG]) had no differential effect on concentrations of melatonin or its major enzymatic metabolite (6‐hydroxymelatonin sulfate, 6‐OHMS) in daily morning urine samples, compared to equivalent no‐exposure sham control conditions. The consistency of intra‐individual urinary measurements over the 4 test nights also was quite high ( P <0.01) in the sham control condition. In contrast, repeated nightly exposure to the magnetic field was associated with reduced consistency. Morning urinary measures obtained after exposure on night 4 differed ( P <0.01) from similar measures obtained after the second and third exposure night. Thus, while the overall results of this study do not support the melatonin hypothesis, there is some suggestion of a possible cumulative effect of magnetic field exposure on the stability of individual melatonin measurements over time. Additional research with longer periods of controlled exposure may be warranted.