Study type: Medical/biological study (experimental study)

Do GSM 900 MHz signals affect cerebral blood circulation? A near-infrared spectrophotometry study. med./bio.

Published in: Opt Express 2006; 14 (13): 6128-6142

Aim of study (acc. to author)

To study the effects of GSM 900 MHz signals on the cerebral blood circulation using near-infrared spectrophotometry (NIRS) in 16 healthy volunteers.

Background/further details

NIRS has been well established as a tool to study activity of the brain and e.g. applied to record changes in oxy-hemoglobin and deoxy-hemoglobin concentrations in the visual and motor cortices during functional stimulation. Oxy-hemoglobin and deoxy-hemoglobin are related to cerebral blood flow and cerebral blood volume.
Compared to previous studies using positron emission tomography, NIRS provides a much higher time resolution, which allows investigating the short term effects efficiently, non-invasively, without the use of radioactive tracers and with high sensitivity.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 900 MHz
Modulation type: pulsed
Exposure duration: 15 cycles: 20 s exposure (intermittend 2 s on/2 s off) and 60 s rest (total of 24 min.)
  • SAR: 1.2 W/kg spatial average (10 g)
  • SAR: 12 W/kg spatial average (10 g)

Exposure 1

Main characteristics
Frequency 900 MHz
Type
Exposure duration 15 cycles: 20 s exposure (intermittend 2 s on/2 s off) and 60 s rest (total of 24 min.)
Modulation
Modulation type pulsed
Repetition frequency 217 Hz
Exposure setup
Exposure source
Setup The antenna was positioned on a location close to the left ear.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1.2 W/kg spatial average calculated 10 g -
SAR 12 W/kg spatial average calculated 10 g -

Reference articles

  • Huber R et al. (2003): Radio frequency electromagnetic field exposure in humans: Estimation of SAR distribution in the brain, effects on sleep and heart rate.

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)

During exposure (within 20 s) borderline significant short term responses of oxy-hemoglobin and deoxy-hemoglobin concentrations were observed, which correspond to a decrease of cerebral blood flow and cerebral blood volume and were much smaller than regular physiological changes elicited e.g. by functional activation of the brain.
There was no detectable dose-response relation or long term response within 20 minutes.

Study character:

Study funded by

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