Medical/biological study (observational study)

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

By: Ichinose TY, Burch JB, Noonan CW, Yost MG, Keefe TJ, Bachand A, Mandeville R, Reif JS

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

effects on the immune system: effects on white blood cells and melatonin level

Exposure

- 60 Hz
- 50/60 Hz
- magnetic field
- occupational

Exposure	Parameters
Exposure 1: 60 Hz Exposure duration: continuous group 1	magnetic flux density: 0.04 µT mean (± 0.01)
Exposure 2: 60 Hz Exposure duration: continuous group 2	magnetic flux density: 0.05 µT mean (± 0.01)
Exposure 3: 60 Hz Exposure duration: continuous group 3	magnetic flux density: 0.08 µT mean (± 0.01)
Exposure 4: 60 Hz Exposure duration: continuous group 4	magnetic flux density: 0.25 µT mean (± 0.2)

Exposure 1

Main characteristics

Frequency	60 Hz
Type	magnetic field
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

Additional parameter details

exposure values for quartiles were time-weighted average values of day 3 work shifts during the sampling trials; over the whole population, values from 0.02 - 4.6 µT with an arithmetic mean of 0.3 µT were found

Exposure 2

Main characteristics

Frequency	60 Hz
Type	magnetic field
Exposure duration	continuous
Additional info	group 2

Exposure setup

Exposure source	not specified same setup as exposure 1

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	0.05 µT	mean	measured	-	± 0.01

Additional parameter details

Exposure 3

Main characteristics

Frequency	60 Hz
Type	magnetic field
Exposure duration	continuous
Additional info	group 3

Exposure setup

Exposure source	not specified same setup as exposure 1

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	0.08 µT	mean	measured	-	± 0.01

Additional parameter details

Exposure 4

Main characteristics

Frequency	60 Hz
Type	magnetic field
Exposure duration	continuous
Additional info	group 4

Exposure setup

Exposure source	not specified same setup as exposure 1

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	0.25 µT	mean	measured	-	± 0.2

Additional parameter details

Reference articles

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

Exposed system:

human
whole body

Methods Endpoint/measurement parameters/methodology

cell viability/cell division/proliferation: proliferation of white blood cells (ornithine decarboxylase enzyme activity; incubation of cells on radioactively labeled enzyme substrate with an without lectin, scintillation counting)
effects on the immune system: cell viability and total and differential count of white blood cells (number of lymphocytes, neutrophils, monocytes, eosinophils, basophils and T cell subsets (T lymphocytes, T helper cells, cytotoxic T lymphocytes, B cells and NK cells); immunohistochemical stain, flow cytometry); NK cell activity (cell labelling with ⁵¹Cr and release after incubation, gamma radiation counter)
endocrine changes: 6-hydroxymelatoninsulfate level in urine (radioimmunoassay)
questionnaire on factors with potential influence on the immune system (73 items including age, height, weight, race/ethnicity, health status, exposure to workplace chemicals, smoking behavior, alcohol and caffeine consumption, vitamin consumption, fruit and vegetable intake, exercise, the current use of "over-the-counter" cold remedies and anti-inflammatory medications, income and education)

Investigated system:

isolated bio./chem. substance
intact cell/cell culture
urine and blood samples, cell lysates
investigation on living organism

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:

medical/biological study
observational study
full/main study

Study funded by

National Institute of Environmental Health Sciences/National Institute of Health (NIEHS/NIH), USA

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Touitou Y et al. (2013): Long-term (up to 20 years) effects of 50-Hz magnetic field exposure on immune system and hematological parameters in healthy men
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Kula B et al. (1999): Effect of Electromagnetic Field on Serum Biochemical Parameters in Steelworkers
Burch JB et al. (1999): Reduced excretion of a melatonin metabolite in workers exposed to 60 Hz magnetic fields
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Pfluger DH et al. (1996): Effects of exposure to 16.7 Hz magnetic fields on urinary 6-hydroxymelatonin sulfate excretion of Swiss railway workers

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

Aim of study (acc. to author)

Background/further details

Endpoint

Exposure

Exposure 1

Main characteristics

Exposure setup

Parameters

Additional parameter details

Exposure 2

Main characteristics

Exposure setup

Parameters

Additional parameter details

Exposure 3

Main characteristics

Exposure setup

Parameters

Additional parameter details

Exposure 4

Main characteristics

Exposure setup

Parameters

Additional parameter details

Reference articles

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

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