Study type: Medical/biological study (experimental study)

Effects of pulsed and continuous wave 902 MHz mobile phone exposure on brain oscillatory activity during cognitive processing. med./bio.

Published in: Bioelectromagnetics 2007; 28 (4): 296-308

Aim of study (acc. to author)

The aim of the study was to partially replicate the data of previous studies (publication 10459, publication 5719, and publication 3600) and to further investigate the possible effects of electromagnetic fields emitted by mobile phones on the event related desynchronisation/synchronisation (ERD/ERS) EEG responses during cognitive processing.

Background/further details

One group of 36 male subjects performed an auditory memory task and another group (also 36 male participants) performed a visual working memory task in six exposure conditions: sham exposure, continuous wave electromagnetic field exposure and pulse modulated electromagnetic field exposure during both left- and right-side exposure, while the EEG was recorded.
The same cognitive tasks as in the previous studies were used.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 902 MHz
Modulation type: CW
Exposure duration: continuous for about 54 or 80 min
  • power: 0.25 W mean
  • SAR: 0.738 W/kg average over mass (10 g)
  • SAR: 1.1 W/kg average over mass (1 g)
  • SAR: 1.18 W/kg peak value
Exposure 2: 902 MHz
Modulation type: pulsed
Exposure duration: continuous for about 54 or 80 min
  • power: 0.25 W mean
  • SAR: 0.738 W/kg average over mass (10 g)
  • SAR: 1.1 W/kg average over mass (1 g)
  • SAR: 1.18 W/kg peak value

General information

In both experiments, testing was conducted in three sessions (CW, PM, and sham exposure), separated by 1 week, each session with left-sided and right-sided exposure. The exposure conditions were counterbalanced, and a double-blind design was used.

Exposure 1

Main characteristics
Frequency 902 MHz
Type
Exposure duration continuous for about 54 or 80 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Distance between exposed object and exposure source 20 mm
Chamber The subjects were seated in a comfortable chair approx. 1.6 m from a computer screen. The signal generator and the power amplifier were located in an adjacent room.
Setup The dummy mobile phone was attached to the subject's head using an earmuff without metal parts, in which one of the protectors was replaced. The phone was positioned as in normal use. The antenna was located approx. 20 mm from the scalp over the posterior temporal lobe in the left-side exposure, and over the inferior and posterior temporal lobe in the right-side exposure. The difference between the exposure sides was due to the asymmetrical position of the antenna.
Sham exposure A sham exposure was conducted.
Additional info The EMF head-set was originally designed and built by Preece et al. [2005].
Parameters
Measurand Value Type Method Mass Remarks
power 0.25 W mean measured - -
SAR 0.738 W/kg average over mass measured 10 g -
SAR 1.1 W/kg average over mass measured 1 g -
SAR 1.18 W/kg peak value measured - -

Exposure 2

Main characteristics
Frequency 902 MHz
Type
Exposure duration continuous for about 54 or 80 min
Modulation
Modulation type pulsed
Pulse width 0.577 ms
Repetition frequency 217 Hz
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power 0.25 W mean measured - -
SAR 0.738 W/kg average over mass measured 10 g -
SAR 1.1 W/kg average over mass measured 1 g -
SAR 1.18 W/kg peak value measured - -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

In line with the previous studies, the authors observed that the electromagnetic field exposure had modest effects on brain oscillatory responses in the alpha wave range (approximately 8-12 Hz) and had no effects on the behavioural measures. The only statistically significant effect arose during the auditory working memory task between the pulse modulated and continuous wave exposure conditions, such that greater alpha wave ERS and smaller alpha wave ERD responses were recorded during the pulse modulated exposure condition as compared to continuous wave exposure condition.The effects on the EEG ERD/ERS responses were, however, varying, unsystematic and inconsistent with previous reports.
The authors conclude that the effects of electromagnetic fields on brain oscillatory responses may be subtle, variable and difficult to replicate for unknown reasons.

Study character:

Study funded by

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