Study type: Medical/biological study (experimental study)

Experimental investigation of possible warmth perception from a head exposure system for human provocation studies with TETRA handset-like signals. med./bio.

Published in: Bioelectromagnetics 2014; 35 (6): 452-458

Aim of study (acc. to author)

It should be investigated if probands of a blind study could distinguish an exposure to a 385 MHz-TETRA-field from sham exposure by warmth perception and thus compromise the blinding.

Background/further details

15 male probands were tested three times per exposure condition (sham exposure, exposure to TETRA-field with specific absorption rate of 1.5 W/kg and 6 W/kg), respectively, resulting in nine different sessions per proband. Each session lasted for 1 h and included preparation, 30 minutes of exposure with simultaneous temperature measurement of the exposed skin and a subsequent questionnaire to account for subjective warmth perception.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 385 MHz
Modulation type: pulsed
Exposure duration: continuous for 30 minutes
  • SAR: 1.5 W/kg average over mass (10 g)
Exposure 2: 385 MHz
Modulation type: pulsed
Exposure duration: continuous for 30 minutes
  • SAR: 6 W/kg average over mass (10 g)

Exposure 1

Main characteristics
Frequency 385 MHz
Type
Waveform
Exposure duration continuous for 30 minutes
Modulation
Modulation type pulsed
Pulse width 14.17 ms
Duty cycle 25 %
Repetition frequency 17.65 Hz
Exposure setup
Exposure source
Setup A body-worn antenna with two integrated thermometers was fixed at the left ear and simulated the exposure to a TETRA-handset.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1.5 W/kg average over mass - 10 g -

Exposure 2

Main characteristics
Frequency 385 MHz
Type
Waveform
Exposure duration continuous for 30 minutes
Modulation
Modulation type pulsed
Pulse width 14.17 ms
Duty cycle 25 %
Repetition frequency 17.65 Hz
Exposure setup
Exposure source
Setup A body-worn antenna with two integrated thermometers was fixed at the left ear and simulated the exposure to a TETRA-handset.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 6 W/kg average over mass - 10 g -

Reference articles

  • Schmid G et al. (2012): Design and dosimetric analysis of a 385 MHz TETRA head exposure system for use in human provocation studies.

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)

The temperatures of the investigated skin parts did not show any significant differences between the exposure to a specific absorption rate of 1.5 W/kg and sham exposure. The exposure to a specific absorption rate of 6 W/kg led to a significant increase of 0.8°C on average compared to sham exposure, though. However, the assessment of the questionnaires revealed that the probands were not able to sense the difference in temperature.
The authors conclude that similar test designs with intensities up to a specific absorption rate of 6 W/kg do not compromise blinding in studies.

Study character:

Study funded by

Related articles