Study type: Medical/biological study (experimental study)

Exposure to GSM RF Fields Does Not Affect Calcium Homeostasis in Human Endothelial Cells, Rat Pheocromocytoma Cells or Rat Hippocampal Neurons. med./bio.

Published in: PLoS One 2010; 5 (7): e11828

Aim of study (acc. to author)

To study the putative changes in cellular Ca2+ homeostasis during exposure of cells to 900 MHz GSM fields of differing power in three different cell types.

Background/further details

A novel microscope-based high throughput screening system was applied that allowed the automatic analysis of cells under different exposure regimes.
The experiment consisted of a screening phase and a provocation phase. Within the screening phase all cell types were tested to a 2 W/kg 900 MHz GSM field (30 minutes). If significant changes in Ca2+ level were observed under exposure, additional experiments would be performed at lower SAR values to determine the threshold for the effect. If no significant effects were observed in the screening phase, provocation experiments are undertaken where the Ca2+ homeostasis would be deliberately perturbed: calcium release from intracellular stores was evoked by application of histamine, whilst passive calcium efflux and calcium entry were stimulated by incubation with thapsigargin. For these experiments, the EA.hy926 cells were used and tested at a number of lower SAR values, using both continuous wave and GSM modulation.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 900 MHz
Modulation type: pulsed
Exposure duration: continuous for 30 min.
Screening test with all cell types
Exposure 2: 900 MHz
Modulation type: pulsed
Exposure duration: continuous for 30 min.
Exposure 3: 900 MHz
Modulation type: CW
Exposure duration: continuous for 30 min.

Exposure 1

Main characteristics
Frequency 900 MHz
Type
Charakteristic
Exposure duration continuous for 30 min.
Additional info Screening test with all cell types
Modulation
Modulation type pulsed
Repetition frequency 217 Hz
Additional info

GSM signal

Exposure setup
Exposure source
Setup exposure system consisted of 2 identical TEM cells that were designed to hold a single coverslip each (22 mm diameter) in a Teflon ring sandwich chamber; the bottom conductor of the TEM cell contained hole to allow optical access to the cells for imaging purposes; a personal computer controlled the exposure conditions by setting the amplified power output of the Agilent ESG-D RF Signal Generator to one of the two TEM cells, through an in-line bidirectional coupler and an RF switch; an Agilent EPM-P Power meter measured the incident and reflected power at each TEM cell; samples placed in the center of the TEM cell
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 2 W/kg - - - for all cultures
SAR 0.25 W/kg - - - only for PC-12 cells
SAR 0.5 W/kg - - - only for PC-12 cells
SAR 1 W/kg - - - only for PC-12 cells

Exposure 2

Main characteristics
Frequency 900 MHz
Type
Charakteristic
Exposure duration continuous for 30 min.
Additional info Provocation test with human endothelial cells
Modulation
Modulation type pulsed
Repetition frequency 217 Hz
Additional info

GSM signal

Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.012 W/kg - - - -
SAR 0.062 W/kg - - - -
SAR 0.125 W/kg - - - -
SAR 0.25 W/kg - - - -
SAR 0.5 W/kg - - - -
SAR 1 W/kg - - - -
SAR 2 W/kg - - - -

Exposure 3

Main characteristics
Frequency 900 MHz
Type
Charakteristic
Exposure duration continuous for 30 min.
Additional info Provocation test with human endothelial cells
Modulation
Modulation type CW
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.012 W/kg - - - -
SAR 0.062 W/kg - - - -
SAR 0.125 W/kg - - - -
SAR 0.25 W/kg - - - -
SAR 0.5 W/kg - - - -
SAR 1 W/kg - - - -
SAR 2 W/kg - - - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The data indicate that 900 MHz GSM fields did not affect either basal Ca2+ homeostasis or provoked Ca2+ signals. Even at the highest field strengths applied, which exceed typical mobile phone exposure levels, no changes in cellular Ca2+ signals were found.
The authors conclude that under the conditions employed in these experiments, and using a highly-sensitive assay, no consequence of radiofrequency exposure could be detected.

Study character:

Study funded by

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