Study type: Medical/biological study (experimental study)

Effects of high frequency electromagnetic field (EMF) emitted by mobile phones on the human motor cortex. med./bio.

Published in: Bioelectromagnetics 2007; 28 (7): 553-561

Aim of study (acc. to author)

To study whether the pulsed radiofrequency electromagnetic field generated by a mobile phone has short-term effects on the human motor cortex.

Background/further details

Motor evoked potentials elicited by single pulse transcranial magnetic stimulation, before and after mobile phone exposure were measured in 10 normal subjects and two patients with multiple sclerosis (MS) showing temperature dependent neurological symptoms. Corticospinal tracts of these patients are more susceptible to high temperature than those of normal subjects. Motor evoked potentials of these MS-patients were also recorded before and after taking a bath for 30 min (42°C).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 800 MHz
Modulation type: pulsed
Exposure duration: continuous for 30 min
  • power: 800 mW peak value
  • power: 270 mW mean
  • SAR: 0.054 W/kg average over mass (10 g) (± 0.02 W/kg)

Exposure 1

Main characteristics
Frequency 800 MHz
Type
Exposure duration continuous for 30 min
Modulation
Modulation type pulsed
Pulse width 6.7 ms
Duty cycle 33.5 %
Additional info

three channel TDMA with 20 ms frame length and π/4 shifted QPSK

Exposure setup
Exposure source
Distance between exposed object and exposure source 4 cm
Setup Subjects held the handset in the normal position for use over the left ear with the top of the antenna located about 4 cm from the head.
Sham exposure A sham exposure was conducted.
Additional info Single and paired pulse TMS experiments were performed just before and after the double-blinded real or sham exposures. In both patients with MS, MEPs were recorded before and after taking a bath for 30 min at 42 °C.
Parameters
Measurand Value Type Method Mass Remarks
power 800 mW peak value - - -
power 270 mW mean - - -
SAR 0.054 W/kg average over mass measured 10 g ± 0.02 W/kg

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • before exposure
  • after exposure

Main outcome of study (acc. to author)

Neither motor evoked potentials nor the short interval intracortical inhibition were affected by 30 min of mobile phone exposure or sham exposure. In two multiple sclerosis patients, mobile phone exposure had no effect on any parameters of motor evoked potentials as well.
Under these experimental conditions the authors did not detect any short-term effects of 30 min mobile phone exposure on the human motor cortical output neurons or interneurons even though they can not exclude the possibility that they failed to detect some mild effects due to a small sample size.

Study character:

Study funded by

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