Study type: Medical/biological study (experimental study)

Changes in human EEG caused by low level modulated microwave stimulation. med./bio.

Published in: Bioelectromagnetics 2004; 25 (6): 431-440

Aim of study (acc. to author)

To study the effects of low level microwave exposure on human EEG alpha and theta rhythms.

Background/further details

The experimental protocol consisted of one cycle of short term photic stimulation and ten cycles of the repetitive microwave stimulation.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 450 MHz
Modulation type: pulsed
Exposure duration: intermittent, 60 s on/60 s off, for 20 min

Exposure 1

Main characteristics
Frequency 450 MHz
Type
Exposure duration intermittent, 60 s on/60 s off, for 20 min
Modulation
Modulation type pulsed
Duty cycle 50 %
Repetition frequency 7 Hz
Exposure setup
Exposure source
Distance between exposed object and exposure source 10 cm
Chamber The subjects lay in a dark room in a relaxed position, eyes closed and ears blocked.
Setup The antenna was located at 10 cm from the skin on the left side of the head.
Sham exposure A sham exposure was conducted.
Additional info Only one EEG recording was performed for a subject per day. Test sessions were single blind, and the exposed and sham exposed subjects were randomly assigned.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.16 mW/cm² - measured - at the skin
SAR 9.5 mW/kg - calculated - in the brain

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)

Low frequency modulated, low level microwave irradiation causes changes in the EEG rhythms' energy level. In the majority of individual cases, these changes are not statistically significant. The alterations caused by photic stimulation as well as microwave stimulation were more regular on the alpha rhythm. In the majority of cases, photic stimulation caused changes in the EEG energy level in the occipital region and microwave stimulation in the frontal region. The data demonstrated that microwave stimulation effects became apparent, starting from the third stimulation cycle. The data allowed to determine the following tendencies: 1) microwave stimulation causes an increase in the variability of the EEG energy level, 2) microwave stimulation causes changes in the frontal region in the majority of the cases, 3) repetitive exposures causes more remarkable changes in the EEG rhythms level than short term irradiation.
The physiological mechanisms underlying these effects are not well understood.

Study character:

Study funded by

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