Study type: Medical/biological study (experimental study)

Repeated exposure to low-level extremely low frequency-modulated microwaves affects baseline and scopolamine-modified electroencephalograms in freely moving rats. med./bio.

Published in: Int J Radiat Biol 2004; 80 (9): 691-698

Aim of study (acc. to author)

To compare in the EEG of rats the effects of scopolamine (0.1 mg/kg) alone and after repeated exposure to low level microwaves modulated at extremely low frequency.

Background/further details

Scopolamine is an acetylcholine receptor antagonist.
A day before the first microwave exposure and on the day after the last (third) one, control experiments (sham exposure) were performed on the same animals.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 915 MHz
Modulation type: pulsed
Exposure duration: intermittent (1 min on/1 min off) for 3 x10 min with 10 min non-exposure between them per day for a total of 4 days (3 consecutive days, 1 day after application of scopolamine)

Exposure 1

Main characteristics
Frequency 915 MHz
Type
Exposure duration intermittent (1 min on/1 min off) for 3 x10 min with 10 min non-exposure between them per day for a total of 4 days (3 consecutive days, 1 day after application of scopolamine)
Modulation
Modulation type pulsed
Pulse width 20 ms
Repetition frequency 4 Hz
Pulse type rectangular
Exposure setup
Exposure source
Chamber The experimental box (Plexiglas, 15 x 17 x 30 cm) was placed in a MW anechoic (with pyramidal Eccosorb) electrically shielded chamber. All metallic parts and generators were located outside the chamber.
Setup A circular wire antenna (18 cm in diameter) fixed in horizontal plane at a distance of 25 cm above the animal was used. At that position of antenna, vertical direction and good homogeneity of MW field propagation was ensured. The MW currents in the antenna were supplied by a high-frequency generator tuned at 915 MHz, which in turn was operated by a low-frequency generator.
Additional info Rats were irradiated intermittently (1-min field-on and 1-min field-off periods) during three 10-min sessions with a 10-min non-exposure between them. Rats were exposed to MW in 3 consecutive days (30 min/day). A day before the first MW exposure and on the day after the last (third) one, control (sham) experiments (the MW power was turned off) were performed on the same animals. Other rats were used in all 5-day sham sessions as a control for the MW exposure series. On the next day after the fifth session, experiments with physiological saline injection were performed on all animals. A day later, both the MW-exposed and sham-irradiated rats were randomly divided into two groups and given either scopolamine or physiological saline. Each injection was made 10 min before application of MW or sham exposure as above.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.3 mW/cm² average over time - - -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The findings provide evidence that repeated low level exposure to extremely low frequency microwaves can modify an activity of cholinergic system in the brain.
Microwave exposure alone significantly enhanced the fast EEG rhythms (18-30 Hz) which was also observed in 10 minutes break periods between exposures. This effect was found neither in subsequent sham exposure experiment nor in irradiation-naive rats.
In the microwave-exposed animals, scopolamine did not cause a slowing in the EEG that was shown in non-exposed rats.

Study character:

Study funded by

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