Study type: Medical/biological study (experimental study)

Radio frequency electromagnetic field exposure in humans: Estimation of SAR distribution in the brain, effects on sleep and heart rate. med./bio.

Published in: Bioelectromagnetics 2003; 24 (4): 262-276

Aim of study (acc. to author)

Extended analysis of the effects of radiofrequency electromagnetic field exposure with two different distributions of the SAR on EEG topography and on heart rate. Additionally, detailed dosimetry of the brain areas is presented.

Background/further details

In two previous studies the authors demonstrated that radiofrequency electromagnetic fields similar to those emitted by digital mobile phone handsets affect brain physiology of subjects exposed to radiofrequency electromagnetic fields either during sleep or during the waking period preceding sleep (see publication 758 and publication 4766).
First experiment: Subjects were exposed intermittently during an 8 h nighttime sleep episode (for details see publication 758).
Second experiment: Subjects were exposed unilaterally for 30 min prior to a 3 h daytime sleep episode (for details see publication 4766).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 900 MHz
Modulation type: pulsed
Exposure duration: intermittent, 15 min on/off for 8 h
  • SAR: 1 W/kg maximum (10 g)
Exposure 2: 900 MHz
Modulation type: pulsed
Exposure duration: continuous for 30 min
  • SAR: 1 W/kg maximum (10 g)

Exposure 1

Main characteristics
Frequency 900 MHz
Type
Charakteristic
Exposure duration intermittent, 15 min on/off for 8 h
Modulation
Modulation type pulsed
Pulse width 0.577 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Additional info

synthesized base station-like signal with seven bursts (slots 0-6) on and one off (slot 7); several frames of the multiframe (104 basic frames) were additionally modified; this signal structure resulted in the spectral components of 2, 8, and 217 Hz, plus the corresponding harmonics; the burst and the intermittency (20 µs) between the bursts led to additional components at 1733 Hz and 50 kHz

Exposure setup
Exposure source
Distance between exposed object and exposure source 30 cm
Chamber absorber walls were placed around the antennas and the bed
Setup array of three half-wavelength dipole antennas (30 cm apart) mounted behind the head of the recumbent subject at a distance of 30 cm; distance between the top of the subject's head and the antenna array varied during sleep between 30-45 cm and the angle of incidence from -45° to 45°
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1 W/kg maximum cf. remarks 10 g -

Exposure 2

Main characteristics
Frequency 900 MHz
Type
Charakteristic
Exposure duration continuous for 30 min
Modulation
Modulation type pulsed
Additional info

same signal as in E1

Exposure setup
Exposure source
Distance between exposed object and exposure source 11 cm
Setup antennas mounted at both sides of the head at a distance of 115 ± 5 mm, with the center of the antenna at 42 ± 10 mm vertically above the ear canal
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1 W/kg maximum cf. remarks 10 g -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Compared to sham exposure, spectral power of the non-REM sleep electroencephalogram was initially increased in the 9-14 Hz range in both experiments. No topographical differences with respect to the effect of radiofrequency electromagnetic field exposure were found in the two experiments. Even unilateral irradiation during waking induced a similar effect in both hemispheres. Exposure during sleep reduced waking after sleep onset and affected heart rate variability. Irradiation prior to sleep reduced heart rate during waking and stage 1 sleep.
Simulations of the SAR distribution within the brain support the interpretation that subcortical structures may be responsible for the revealed effect on the sleep EEG.

Study character:

Study funded by

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