Study type: Medical/biological study (observational study)

Immune markers and ornithine decarboxylase activity among electric utility workers. med./bio.

Published in: J Occup Environ Med 2004; 46 (2): 104-112

Aim of study (acc. to author)

The effects of an occupational exposure of electric utility workers to a 60 Hz magnetic field on the immune system should be investigated.

Background/further details

60 male workers with employment in electric power generation (n=12), distribution (n=31) or utility maintenance and administration (n=17) of an electric utility participated in the study. Regardless of their employment, the subjects were divided into 4 groups (quartiles, n=15 each) according to the mean values of their personal magnetic field exposure: groups 1, 2, 3 and 4.
4 sampling trials were conducted during 1 year. In each trial, after a non-work baseline day and the following 3 working days, overnight urine samples were collected (days 0, 1, 2, and 3), respectively. This procedure was repeated quarterly over the year. Additionally, subjects provided a blood sample at the end of day 3 during their third quarter of participation.
Melatonin was investigated because of its immunostimulating effect.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 60 Hz
Exposure duration: continuous
group 1
Exposure 2: 60 Hz
Exposure duration: continuous
group 2
Exposure 3: 60 Hz
Exposure duration: continuous
group 3
Exposure 4: 60 Hz
Exposure duration: continuous
group 4

Exposure 1

Main characteristics
Frequency 60 Hz
Type
Exposure duration continuous
Additional info group 1
Exposure setup
Exposure source
  • not specified
Setup during the workdays of each sampling trial, subjects wore exposimeters at the waist during waking hours and placed bedside adjacent to the waist during sleeping to measure exposure and ambient light
Additional info (remark EMF-Portal: no information is given on exposure levels for the employment groups or on the subjects' actual exposure durations)
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.04 µT mean measured - ± 0.01

Exposure 2

Main characteristics
Frequency 60 Hz
Type
Exposure duration continuous
Additional info group 2
Exposure setup
Exposure source
  • same setup as exposure 1
  • not specified
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.05 µT mean measured - ± 0.01

Exposure 3

Main characteristics
Frequency 60 Hz
Type
Exposure duration continuous
Additional info group 3
Exposure setup
Exposure source
  • same setup as exposure 1
  • not specified
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.08 µT mean measured - ± 0.01

Exposure 4

Main characteristics
Frequency 60 Hz
Type
Exposure duration continuous
Additional info group 4
Exposure setup
Exposure source
  • same setup as exposure 1
  • not specified
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.25 µT mean measured - ± 0.2

Reference articles

  • Yost M (1999): Alternative Magnetic Field Exposure Metrics: Occupational Measurements in Trolley Workers

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

The proliferation of white blood cells and NK cell numbers in the blood were significantly decreased among workers with the highest magnetic field exposure (group 4) compared to workers with the lowest MF exposure (group 1).
These effects were most distinct in probands with a reduced melatonin level, who showed additionally significantly decreased B cell and monocyte numbers compared to the rest of the population (remark EMF-Portal: the reduced melatonin level was brought into relation with the magnetic field but this was not statistically secured).
All other parameters did not show any significant associations with the magnetic field exposure.
The authors conclude that an occupational exposure of electric utility workers to a 60 Hz magnetic field might have an effect on the immune system although consequences for health are unknown.

Study character:

Study funded by

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