Study type: Medical/biological study (experimental study)

Effect of low frequency modulated microwave exposure on human EEG: Individual sensitivity. med./bio.

Published in: Bioelectromagnetics 2008; 29 (7): 527-538

Aim of study (acc. to author)

To evaluate the effect of modulated microwave exposure (450 MHz) on human EEG.

Background/further details

There were four exposure groups: 1) 7 Hz modulated microwaves (19 subjects), 2) 14 Hz and 21 Hz modulation (13 subjects), 3) 40 Hz and 70 Hz modulation (15 subjects), 4) 217 Hz and 1000 Hz modulation (19 subjects).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 450 MHz
Modulation type: pulsed
Exposure duration: intermittent, 1 min off/1 min on, for 20 min
Exposure 2: 450 MHz
Modulation type: pulsed
Exposure duration: intermittent, 1 min off/1 min on, for 40 min

General information

Microwave exposure was identical to that in previous studies [Lass et al., 2002; Hinrikus et al., 2004] with the only exception that several different modulation frequencies were applied.

Exposure 1

Main characteristics
Frequency 450 MHz
Type
Exposure duration intermittent, 1 min off/1 min on, for 20 min
Modulation
Modulation type pulsed
Duty cycle 50 %
Repetition frequency 7 Hz
Exposure setup
Exposure source
  • monopole
  • quarter-wave antenna (13 cm)
Distance between exposed object and exposure source 10 cm
Setup The rod monopole antenna was located 10 cm from the skin on the left side of the head at a vertical angle of 45°.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.16 mW/cm² mean measured - -
SAR 0.303 W/kg peak value calculated 1 g spatial peak value

Exposure 2

Main characteristics
Frequency 450 MHz
Type
Exposure duration intermittent, 1 min off/1 min on, for 40 min
Modulation
Modulation type pulsed
Duty cycle 50 %
Additional info

Pulse rates of 14 and 21 Hz or 40 and 70 Hz or 217 and 1000 Hz were applied.

Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Additional info Each modulation frequency of a pair was applied for the first or second 10 cycles (20 min) in random order. For each session, the exposure conditions (RF or sham) were randomly assigned between subjects.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.16 mW/cm² mean measured - -
SAR 0.303 W/kg peak value calculated 1 g spatial peak value

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 subjects significantly affected by modulated microwaves were found within all groups with the exception of the 1000 Hz modulated group. The findings showed that exposure caused significant increases in the EEG beta rhythms energy for 13- 31% of the subjects. In groups of subjects modulated at two different frequencies, in most cases the same subjects were sensitive at both modulation frequencies (except the fourth group at 1000 Hz modulation frequency).
Sensitivity of some subjects to microwave exposure is most likely related not to hypersensitivity of these individuals but to variability of the physiological state of the brain.
In conclusion, the data support the hypothesis that the effect of microwaves differs among individuals.

Study character:

Study funded by

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