Study type: Medical/biological study (experimental study)

Effect of global system for mobile communication microwave exposure on the genomic response of the rat brain. med./bio.

Published in: Neuroscience 1997; 81 (3): 627-639

Aim of study (acc. to author)

To investigate whether acute exposure to 900 MHz microwaves under conditions closely related to GSM mobile telephony leads to a similar gene activation in brain tissue as other established pathological conditions and, therefore, could promote degenerative processes in the brain.

Background/further details

The effects were studied by measuring changes in the mRNA of hsp70, the transcription factor genes c-fos and c-jun and the glial structural gene GFAP, by measuring protein products of transcription factors, stress proteins, marker proteins of glial activation and by measuring cell proliferation.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 890–915 MHz
Modulation type: pulsed
Exposure duration: continuous for 4 h
  • power: 1 W average over time (antenna input)
  • SAR: 0.3 W/kg average over mass (brain)
  • SAR: 0.17 W/kg average over mass (whole body)
  • SAR: 0.7 W/kg maximum (cf. remarks) (spatial peak value averaged over 0.05 g of brain tissue)
Exposure 2: 890–915 MHz
Modulation type: pulsed
Exposure duration: continuous for 4 h
  • power: 5 W average over time (antenna input)
  • SAR: 1.5 W/kg average over mass (brain)
  • SAR: 0.84 W/kg average over mass (whole body)
  • SAR: 3.5 W/kg maximum (cf. remarks) (spatial peak value averaged over 0.05 g of brain tissue)
Exposure 3: 900 MHz
Modulation type: CW
Exposure duration: continuous for 4 h
  • power: 25 W average over time (antenna input)
  • SAR: 7.5 W/kg average over mass (brain)
  • SAR: 4.2 W/kg average over mass (whole body)
  • SAR: 17.5 W/kg maximum (cf. remarks) (spatial peak value averaged over 0.05 g of brain tissue)

General information

Rats were assigned to five groups (n=30 each): free moving control group, sham-exposed control group, and three groups exposed at different levels.

Exposure 1

Main characteristics
Frequency 890–915 MHz
Exposure duration continuous for 4 h
Modulation
Modulation type pulsed
Repetition frequency 217 Hz
Additional info

discontinuous transmission mode

Exposure setup
Exposure source
Setup Animals were placed in a ventilated Plexiglas carousel consisting of ten circularly arranged tubes with their heads as close as possible to the central antenna. The GSM phone was controlled by a GSM RF Test Set, and a conversation was simulated.
Parameters
Measurand Value Type Method Mass Remarks
power 1 W average over time - - antenna input
SAR 0.3 W/kg average over mass measured and calculated brain -
SAR 0.17 W/kg average over mass calculated whole body -
SAR 0.7 W/kg maximum calculated cf. remarks spatial peak value averaged over 0.05 g of brain tissue

Exposure 2

Main characteristics
Frequency 890–915 MHz
Exposure duration continuous for 4 h
Modulation
Modulation type pulsed
Repetition frequency 217 Hz
Additional info

discontinuous transmission mode

Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power 5 W average over time - - antenna input
SAR 1.5 W/kg average over mass measured and calculated brain -
SAR 0.84 W/kg average over mass calculated whole body -
SAR 3.5 W/kg maximum calculated cf. remarks spatial peak value averaged over 0.05 g of brain tissue

Exposure 3

Main characteristics
Frequency 900 MHz
Exposure duration continuous for 4 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Additional info In a control experiment the rectal temperature of anaesthetized rats was monitored during high dose exposure at 25 W, 37.5 W and 50 W antenna input power.
Parameters
Measurand Value Type Method Mass Remarks
power 25 W average over time - - antenna input
SAR 7.5 W/kg average over mass measured and calculated brain -
SAR 4.2 W/kg average over mass calculated whole body -
SAR 17.5 W/kg maximum calculated cf. remarks spatial peak value averaged over 0.05 g of brain tissue

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The results indicate that acute high intensity microwave exposure may induce some minor stress response but does not result in lasting changes of the brain. In situ hybridization revealed slight induction of hsp70 mRNA in the cerebellum and hippocampus after 7.5 W/kg exposure, but not at lower intensities. A slightly increase expression of c-fos mRNA was observed in the cerebellum, neocortex and piriform cortex of all groups, but no differences were found amongst different exposure conditions. c-jun and GFAP mRNA did not increase in any of the exposed groups. Immunocytochemical analysis (24h after exposure) of FOS and JUN proteins, of HSP70 or of KROX-20 and -24 did not reveal any alterations. Seven days after exposure, neither increased cell proliferation nor altered expression of glial marker proteins were observed.

Study character:

Study funded by

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