Study type: Medical/biological study (experimental study)

Non-linear analysis of the electroencephalogram for detecting effects of low-level electromagnetic fields med./bio.

Published in: Med Biol Eng Comput 2005; 43 (1): 142-149

Aim of study (acc. to author)

To compare the sensibility of non-linear analysis of length distribution of low-variability periods (LDLVP) and linear spectral analysis to study EEG signals with and without the influence of a low-level modulated microwave field.

Background/further details

23 subjects participated (12 men, 11 women). All subjects passed two EEG recordings on two different days under microwave exposure and sham exposure.



Exposure Parameters
Exposure 1: 450 MHz
Modulation type: AM
Exposure duration: "60 s exposure, 60 s recording interval" (this cycle was repeated 10 times)

Exposure 1

Main characteristics
Frequency 450 MHz
Exposure duration "60 s exposure, 60 s recording interval" (this cycle was repeated 10 times)
Modulation type AM
Modulation frequency 7 Hz
Modulation depth 100 %
Exposure setup
Exposure source
Distance between exposed object and exposure source 10 cm
Setup antenna placed on the left side of the subject's head
Sham exposure A sham exposure was conducted.
Measurand Value Type Method Mass Remarks
power 1 W - - - -
power density 0.16 mW/cm² - estimated - at the scalp
SAR 0.35 W/kg - calculated brain -

Reference articles

  • Lass J et al. (2002): Effects of 7 Hz-modulated 450 MHz electromagnetic radiation on human performance in visual memory tasks

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 LDLVP method provided a significant detection of the effect of the microwave stressor for six subjects exposed to the microwave field but for none of the sham exposure recordings. The spectral power analysis revealed a significant result for one subject only. A significant effect of the exposure on the EEG signal was detected in 25% of subjects (by LDLVP analysis): microwave exposure increased EEG variability. The effect was not detectable by power spectral measures.
In conclusion, non-linear LDLVP method is a sensitive method for distinguishing EEG signals with and without a weak stressor and is superior to spectral analysis.

Study character:

Study funded by

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