Study type: Medical/biological study (experimental study)

Light and electron microscopic study of the thyroid gland in rats exposed to power-frequency electromagnetic fields. med./bio.

Published in: J Exp Biol 2006; 209: 3322-3328

Aim of study (acc. to author)

To study possible harmful effects of power frequency electromagnetic fields on thyroid gland structure in 8-week-old male rats (n=15) exposed to electromagnetic fields for a period of 4 weeks.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: repeated daily exposure, 4 h/day, 5 days a week for 1 month

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
  • unspecified
Exposure duration repeated daily exposure, 4 h/day, 5 days a week for 1 month
Exposure setup
Exposure source
Distance between exposed object and exposure source 12 cm
Setup Cages were placed on both sides of the coil, perpendicular to the coil axis and were covered with plastic lid. The coil axis was parallel to the lines of the force of the geomagnetic field. The electromagnetic field produced by the coil was in horizontal direction with respect to geomagnetic field and was inhomogeneous with decaying intensity along the cage.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 160 V/m unspecified measured - on the side of the cage near the coil
magnetic flux density 300 µT unspecified measured - on the side of the cage near the coil
magnetic flux density 100 µT unspecified measured - at the opposite end of the cage away from coil
electric field strength 54 V/m unspecified measured - at the opposite end of the cage away from coil
magnetic flux density 40 µT unspecified measured - geomagnetic field in north-south direction d: Erdmagnetfeld in Nord-Sü

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The data demonstrated the stimulative effect of a power frequency electromagnetic fields on the thyroid gland.
For example, a predominance of microfollicles with less colloid content and dilated blood capillaries was found in the exposed group. Stereological counting showed a statistically significant increase of the volume density of follicular epithelium, interfollicular tissue and blood capillaries as well as the thyroid activation index, as compared to the controls. Alterations in lysosomes, granular endoplasmic reticulum and cell nuclei compared to the control group were also observed.
Although the structural alterations in the thyroid gland were not so severe as to point to a hazardous effect, they are important in the light of a possible thyroid sensitivity to 50·Hz electromagnetic fields.

Study character:

Study funded by

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