Study type: Medical/biological study (experimental study, observational study)

Effects of electromagnetic fields on the immune systems of occupationally exposed humans and mice. med./bio.

Published in: Arch Environ Health 2003; 58 (11): 712-717

Aim of study (acc. to author)

In a previous study (publication 1968), 13 subjects exposed to extremely low frequency electromagnetic fields, the authors observed a significant decrease in lymphocyte, CD4, CD3, and CD2 counts and an increase in natural killer cells.
Six months following the end of this study, hematological and immunological parameters were measured again for 6 of the same subjects and the results were compared with earlier values. The first aim of the present study was to examine the evolution of hematological values after cessation of occupational exposure. The second aim was to address the controversy regarding comparable effects of electromagnetic fields on animals (mice were exposed in the same room in which the human subjects had been exposed for 109 days).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: 8 h/day for 5 years
Exposure 2: 50 Hz
Exposure duration: repeated daily exposure for 109 days

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 8 h/day for 5 years
Exposure setup
Exposure source
Setup The subjects worked in a laboratory located above the transformers, 13 kV high voltage bus bars and a power generator
Additional info The measurements were preformed at 3 h intervals when the transformers were functioning normally. Control subjects worked in the same building as those exposed, doing the same type of work, but located 50 m away from the transformers and high voltage bus bars.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 200 nT minimum measured - at the floor level
magnetic flux density 6,600 nT maximum measured - at the floor level
magnetic flux density 300 nT minimum measured - to at 1.5 m above the floor
magnetic flux density 1,500 nT maximum measured - to at 1.5 m above the floor
electric field strength 1 V/m minimum measured - -
electric field strength 220 mV/cm maximum measured - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration repeated daily exposure for 109 days
Exposure setup
Exposure source
Setup mice were housed in standard plastic cages (4 mice/cage) which were placed directly on the floor in the same laboratory loacted above the transformers and high voltage bus bars.
Additional info Control mice were housed in the same standard plastic cages and kept in an animal exposure facility under identical light and temperature conditions.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 2.5 V/m unspecified measured - -
magnetic flux density 5 µT unspecified measured - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Six months after exposure had ceased, total lymphocyte counts had increased, as had CD4, CD3, and CD19 counts (+13%, +28%, +22%, and +17%, respectively). Natural killer cell counts were decreased by 26% (not significant) in the same human subjects.
The total lymphocyte, leukocyte, CD4, and natural killer cell counts of the exposed mice at 109 days were significantly lower than those of controls. Additionally, plasma glucose levels (at 30 days) and amylase activity (at 109 days) were significantly lower, whereas plasma sodium and chloride levels were significantly elevated at 109 days.
Data from this study suggest that chronic exposure to a 0.2-6.6-µT magnetic field can lead to decreased immunological parameters in both human and mice.
(Remark of evaluator: the magnetic field of the earth has a flux density from about 30 to 60 µT).

Study character:

Study funded by

Related articles