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.

By: Irlenbusch L, Bartsch B, Cooper J, Herget I, Marx B, Raczek J, Thoss F

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.

Endpoint

effects on the visual system

Exposure

- mobile communications
- digital mobile phone
- GSM

Exposure	Parameters
Exposure 1: 902.4 MHz Modulation type: pulsed Exposure duration: continuous for 30 min	power: 5 W power density: 1 W/m² (without subject) SAR: 0.007 W/kg maximum (1 g) (in the retina) SAR: 0.003 W/kg maximum (10 g) (in the retina)

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
Type	electromagnetic field
Charakteristic	far field
Polarization	circular
Exposure duration	continuous for 30 min

Modulation

Modulation type	pulsed
Repetition frequency	217 Hz

Exposure setup

Exposure source	cellular phone in test mode, power amplifier, 28-cm spiral antenna (2 dB gain)
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.

Parameters

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

Additional parameter details

The background level from other radiation sources was below 1% of the signal used in the experiments.

Measurement and calculation details

The power flux density was measured at the position of the head using a calibrated measurement apparatus for far-field radiation. Numerical dosimetry was performed using the MAFIA™ program employing the finite integration technique (FIT).

Reference articles

Thoss F et al. (2003): The human visual threshold depends on direction and strength of a weak magnetic field

Exposed system:

human
partial body: head

Methods Endpoint/measurement parameters/methodology

effects on the visual system (determination of the visual discrimination threshold)

Investigated system:

investigation on living organism

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:

medical/biological study
experimental study
full/main study
blind study

Study funded by

Deutsche Telekom/T-Systems, Germany

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