Study type: Medical/biological study (experimental study)

No influence on selected parameters of human visual perception of 1970 MHz UMTS-like exposure med./bio.

By: Schmid G, Sauter C, Stepansky R, Lobentanz IS, Zeitlhofer J
Published in: Bioelectromagnetics 2005; 26 (4): 243-250
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Aim of study (acc. to author)

To study possible effects of exposure to a generic 1.97 GHz UMTS-like signal on human visual perception.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1.97 GHz
Exposure duration: see add. information
  • SAR: 0.63 W/kg mean (1 g) (0.25-1.49 W/kg)
  • SAR: 0.37 W/kg mean (10 g) (0.16-0.84 W/kg)

Exposure 1

Main characteristics
Frequency 1.97 GHz
Type
Exposure duration see add. information
Modulation
Modulation type cf. additional info
Additional info

Generic UMTS test signal developed for use in bio-electromagnetic experiments (see reference article) and representing a wideband code division multiple access (WCDMA) signal at a carrier frequency close to the uplink frequency band of UMTS in frequency division duplex (FDD) mode. Due to simulated fading and power control, the signal envelope contained low frequency components of 8-12 and 1,500 Hz.
Exposure setup
Exposure source
Chamber laterally shielded exposure cabin with the inner surface covered by pyramidal RF absorbing material
Setup Test subjects wore a special head set consisting of a modified stereo head phone (all metallic parts removed) with small matched helical antennas mounted in a way to achieve an exposure distribution in the head similar to the case of mobile phone usage. Subjects were exposed only at the left side of the head, but they were not informed about this fact.
Additional info Each subject was tested on a single week day between 3:30 and 7:00 p.m. and underwent four tests used for assessing visual perception under three different exposure conditions (high exposure, low exposure, and sham exposure) that were controlled randomly and double-blinded by control software. Additionally, all tests except the Critical Flicker and Fusion Frequency Test were presented to the subjects under a positive control condition (flicker light applied from the back) at the end of the subject's session.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.63 W/kg mean measured and calculated 1 g 0.25-1.49 W/kg
SAR 0.37 W/kg mean measured and calculated 10 g 0.16-0.84 W/kg
Additional parameter details

SAR values indicated resulted in the cortex of the left temporal lobe of the brain in the high exposure condition. Low exposure condition was defined to be one tenth of high exposure, and sham was at least 50 dB below low exposure. Background ambient field strength measured in the frequency range from DC up to 18 GHz was found to be negligible.

Measurement and calculation details

A detailed dosimetric analysis of the exposure system was based on the power recordings (forward as well as reverse power measurements) obtained during the experiments and extensive numerical simulations using the SEMCAD simulation platform and the anatomical European male head model at a spatial resolution of 1.5-3 mm. The validity of the numerical model of the small helical antennas used was verified prior to the dosimetric analysis by comparisons of experimental and numerical results, showing deviations of less than ±5%. Furthermore, the SAR inside the homogeneous specific anthropomorphic mannequin (SAM) phantom measured using an automated SAR test facility (DASY 3) agreed within ±10% with corresponding SEMCAD calculations. The minimum and maximum values of SAR to be expected in the test subjects' temporal cortex were obtained by an uncertainty analysis, the main contribution (~85%) being due to the variations of the antenna's position with respect to the head, caused by different head sizes and shapes.

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Statistical evaluation of the obtained data revealed no statistically significant differences in the investigated parameters of visual perception between the exposure conditions and sham exposure.

Study character:

Study funded by

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