Study type: Medical/biological study (experimental study)

Mobile phone emissions and human brain excitability. med./bio.

Published in: Ann Neurol 2006; 60 (2): 188-196

Aim of study (acc. to author)

To test - via paired-pulse transcranial magnetic stimulation (ppTMS) - the excitability of each brain hemisphere after real or sham exposure to the electromagnetic field generated by a mobile phone.

Background/further details

ppTMS is a non-invasive diagnostic method to analyse the phenomena of intracortical, transsynaptical inhibition and facilitation.
Intracortical inhibitory/facilitatory curves reflecting intracortical excitability of the motor cortex can be investigated reliably with ppTMS using a pair of conditioning and test stimuli separted by a programmable interval. These measures are symmetrical in the two hemispheres of healthy subjects and are highly reproducible in a test-retest paradigm.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 902.4 MHz
Modulation type: pulsed
Exposure duration: continuous for 45 min

Exposure 1

Main characteristics
Frequency 902.4 MHz
Type
Exposure duration continuous for 45 min
Modulation
Modulation type pulsed
Repetition frequency 217 Hz
Additional info

typical GSM signal

Exposure setup
Exposure source
Distance between exposed object and exposure source 40 mm
Setup The mobile phone was mounted to the left side of the subject's head by a modified helmet assuring a constant distance of 15 mm between the phone and the ear. An identical phone, but without a battery, was positioned on the right side of the head. Both phones were held in the normal position for use with the aerial near the head in the parietotemporal area, about 40 mm from the scalp surface.
Sham exposure A sham exposure was conducted.
Additional info All subjects attended two sessions, one week apart, with the phone turned on or turned off, according to a cross-over, double-blind paradigm.
Parameters
Measurand Value Type Method Mass Remarks
power 2 W peak value - - -
power 0.25 W mean - - -
SAR 0.5 W/kg maximum measured - -

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 intracortical excitability curve became significantly modified during real exposure: short intracortical inhibition was reduced and intracortical facilitation was enhanced in the acutely exposed brain hemisphere as compared to the contralateral, non-exposed hemisphere or to sham exposure. Tympanic temperature revealed no significant effect.
These data demonstrated that GSM electromagnetic fields modify brain excitability.

Study character:

Study funded by

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