Study type: Medical/biological study (experimental study)

Acute exposure to circularly polarized 50-Hz magnetic fields of 200-300 microT does not affect the pattern of melatonin secretion in young men. med./bio.

Published in: J Clin Endocrinol Metab 2003; 88 (12): 5668-73

Aim of study (acc. to author)

The effects of exposure of young men to a 50 Hz magnetic field on the nighttime melatonin profile should be investigated.

Background/further details

The rationale for this study was to determine whether acute exposure to magnetic fields similar to those produced by the power distribution system is capable to alter the human melatonin secretion.
A total of 23 male participants between 18 and 35 years completed two 7-day sessions separated by 7 days in a balanced cross-over design: an exposure session and a sham exposure session. During the first 5 days of each session, participants maintained a regular daily routine and their sleep duration and EMF-exposure was measured with personal devices. During the last 2 days of each session, participants remained in the clinical investigation unit and before going to sleep, they were placed in the exposure unit without current in the first night (baseline) and with exposure or sham exposure in the second night. A total of 8 subjects was exposed to the 200 µT magnetic field and 15 subjects were exposed to 300 µT.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: 2 hours
Exposure 2: 50 Hz
Exposure duration: 2 hours

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Polarization
  • circular
Exposure duration 2 hours
Exposure setup
Exposure source
Setup two sets of orthogonally oriented coils (one north-south, one east-west), each consisting of two sets of 50 windings in series were designed to ensure maximal field uniformity; windings, supported by acrylic formers, fastened together with nylon bolts produced an exposure system of dimensions 900 mm x 900 mm x 900 mm, which was supported by an open-bay trolley to allow in-bed subject exposure; to eliminate confounding effects of vibration, electric fields, noise and heat, windings were bifilar; magnetic fields and sham fields were thus created by unidirectional and bidirectional flow of current, respectively; windings were embedded in silicon sealant to minimize vibration; no shielding from ambient magnetic fields was present; however, background AC fields were constantly monitored and were all less than 0.2 µT
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 200 µT - measured - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Polarization
  • circular
Exposure duration 2 hours
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 300 µT - measured - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • before exposure
  • after exposure

Main outcome of study (acc. to author)

No significant differences in melatonin profile between exposure sessions and sham exposure sessions were found.
The authors conclude that exposure of young men to a 50 Hz magnetic field has no effect on the nighttime melatonin profile.

Study character:

Study funded by

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