Study type: Medical/biological study (experimental study)

Microwaves emitted by cellular telephones affect human slow brain potentials med./bio.

By: Freude G, Ullsperger P, Eggert S, Ruppe I
Published in: Eur J Appl Physiol 2000; 81 (1-2): 18-27
Download citation in RIS format

Aim of study (acc. to author)

To study the influence of electromagnetic fields emitted by cellular phones on preparatory slow brain potentials in two experiments, about 6 months apart.

Background/further details

Preparatory slow brain potentials occur prior to voluntary initiated movements (Bereitschaftspotenzial, BP) or between a warning (S1) and an imperative stimulus (S2) (contingent negative variation, CNV). Preparatory processes are of fundamental importance for effective motor and mental performance in the goal-directed behaviour.
CNV: In the current study the appearance of a pointer of a symbolised clock at the 12 o'clock position represented the S1 stimulus, the beginning of the pointer movement represented the S2 stimulus (as soon as the pointer started to move, the subjects had to stop the pointer by pressing a mouse key).
BP: To investigate the BP the subjects were asked to press a key with their right index finger 30 times at self-paced intervals (simple finger movements).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 916.2 MHz
Modulation type: pulsed
Exposure duration: continuous for about 3 to 4 min per task
  • power: 2.8 W peak value
  • power: 350 mW average over time
  • SAR: 1.42 mW/g average over mass (1 g)
  • SAR: 0.882 mW/g average over mass (10 g)

Exposure 1

Main characteristics
Frequency 916.2 MHz
Type
Exposure duration continuous for about 3 to 4 min per task
Modulation
Modulation type pulsed
Pulse width 577 µs
Repetition frequency 217 Hz
Additional info

no acoustic signal transmission
Exposure setup
Exposure source
Setup The mobile phone was positioned in direct contact to the left ear of the subjects, who sat in an artificially illuminated room in front of a computer monitor. The telephone antenna was fed by a generator and amplifier located in an adjacent room and connected via a coaxial cable.
Additional info Each task was performed in two blocks with and without EMF exposure in counterbalanced order.
Parameters
Measurand Value Type Method Mass Remarks
power 2.8 W peak value measured - -
power 350 mW average over time measured - -
SAR 1.42 mW/g average over mass measured 1 g -
SAR 0.882 mW/g average over mass measured 10 g -
Measurement and calculation details

Power was measured using a power meter at the telephone connector. SAR measurements performed in 1996 on the basis of the CENELEC standard showed the peak values indicated. At the depth of about 14 mm, SAR amounted to about 25% of the energy at the skin surface.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

In the first experiment, a significant decrease of slow brain potentials was found during exposure to electromagnetic fields in a complex visual monitoring task and this effect was replicated in the second experiment. No significant electromagnetic field effects were found in the Bereitschaftspotenzial and CNV tasks. The results accounted for a selective electromagnetic field effect on particular aspects of human information processing. However, they do not indicate any influence on human well-being and health.

Study character:

Study funded by

Related articles