Study type: Medical/biological study (experimental study)

Effects of cellular phone use on ear canal temperature measured by NTC thermistors. med./bio.

Published in: Clin Physiol Funct Imaging 2007; 27 (3): 162-172

Aim of study (acc. to author)

To measure temperature changes in the ear canal before, during and after a 35 min radiofrequency exposure for the two European cellular phone operational frequencies (900 and 1800 MHz).

Background/further details

30 healthy subjects participated. Temperature was measured by using small-sized NTC thermistors placed in the ear canals through ear plugs.
Temperature changes were determined 1) during a 5-min controlled breathing test, 2) during a 5-min spontaneous breathing test, 3) during 7-min head-up tilt test, 4) 1-min before, during and after two consecutive Valsalva's maneuvers and 5) during a deep breathing test.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 900 MHz
Modulation type: pulsed
Exposure duration: continuous for 35 min
Exposure 2: 1,800 MHz
Modulation type: pulsed
Exposure duration: continuous for 35 min

General information

Subjects in this double-randomised, double-blind, and placebo controlled crossover study were exposed on two different days, one week apart, to 900 MHz and 1800 MHz mobile phones.

Exposure 1

Main characteristics
Frequency 900 MHz
Type
Exposure duration continuous for 35 min
Modulation
Modulation type pulsed
Exposure setup
Exposure source
Setup Two mobile phones were located symmetrically leaning on the ears by means of a plastic helmet. The active phone was positioned on the dominant hand side of the head, and the phone on the other side was a dummy without battery.
Sham exposure A sham exposure was conducted.
Additional info The total duration of each session was 2 h including one 35-min RF and one 35-min sham exposure.
Parameters
Measurand Value Type Method Mass Remarks
power 2 W peak value - - -
power 0.25 W mean - - -
SAR 1.58 W/kg maximum measured - -

Exposure 2

Main characteristics
Frequency 1,800 MHz
Type
Exposure duration continuous for 35 min
Modulation
Modulation type pulsed
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power 1 W peak value - - -
power 0.125 W mean - - -
SAR 0.7 W/kg maximum measured - -

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)

Temperatures in the exposed ear were significantly higher during radiofrequency exposures compared with sham exposure with maximum differences of 1.2 +/- 0.5°C (900 MHz) and 1.3 +/- 0.7°C (1800 MHz). Temperatures in the exposed ear were also significantly higher during the post-exposure period compared with post-sham exposure period.
The data indicate that radiofrequency exposure to a cellular phone, either using 900 MHz or 1800 MHz with their maximal allowed antenna powers, increases the temperature in the ear canal (as a consequence of mobile phone battery warming during maximal antenna power use).

Study character:

Study funded by

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