Study type: Medical/biological study (experimental study)

Influence of a 902.4 MHz GSM signal on the human visual system: Investigation of the discrimination threshold. med./bio.

Published in: Bioelectromagnetics 2007; 28 (8): 648-654

Aim of study (acc. to author)

The objective of this study was to investigate whether a GSM exposure for 30 minutes effects the human visual system in vivo.

Background/further details

33 subjects (12 female, 21 male) who had slept adequatly during the previous night, aged between 19 and 27 years, healthy, and normal vision, participated in this study. The visual discrimination threshold was determined in intervals of about 10 seconds to examine the visual sensitivity. Flashes appeared on a screen increasing their luminance in steps up to the moment the subject could recognize them.



Exposure Parameters
Exposure 1: 902.4 MHz
Modulation type: pulsed
Exposure duration: continuous for 30 min

General information

Previous studies on the influence of the geomagnetic field on the VDThr [Thoss et al., 2002; Thoss and Bartsch, 2003] were used as a positive control for this study. Thoss F, Bartsch B, Tellschaft D, Thoss M (2002): The light sensitivity of the visual system depends on the direction of view. J Comp Physiol A 188:235-237.

Exposure 1

Main characteristics
Frequency 902.4 MHz
  • circular
Exposure duration continuous for 30 min
Modulation type pulsed
Repetition frequency 217 Hz
Exposure setup
Exposure source
Chamber The investigation was performed in a soundproof unshielded room. The subject was positioned 0.8 m in front of a white screen behind which the antenna was placed.
Setup At the position of the head, the main radiation lobe was so broad that small movements had negligible influence on SAR values. Reflections were minimized by flat RF absorbers behind and to the left and right of the subject.
Sham exposure A sham exposure was conducted.
Additional info Each subject attended two sessions one week apart: the RF and the sham exposure session, in randomized and single-blind fashion. Each of the sessions consisted of two parts of 30 min each, separated by a 5-min break. For each RF exposure, the field was applied only during the second 30-min part of the session.
Measurand Value Type Method Mass Remarks
power 5 W - measured - -
power density 1 W/m² - measured - without subject
SAR 0.007 W/kg maximum calculated 1 g in the retina
SAR 0.003 W/kg maximum calculated 10 g in the retina

Reference articles

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)

No statistically significant differences in the visual discrimination thresholds were noted in comparing the data obtained for GSM exposure with those for sham exposure.

Study character:

Study funded by

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