Medical/biological study (experimental study)

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

By: Bachmann M, Kalda J, Lass J, Tuulik V, Sakki M, Hinrikus H

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.

Endpoint

effects on the neurological system: EEG

Exposure

- low level microwaves
- AM amplitude modulation

Exposure	Parameters
Exposure 1: 450 MHz Modulation type: AM Exposure duration: "60 s exposure, 60 s recording interval" (this cycle was repeated 10 times)	power: 1 W power density: 0.16 mW/cm² (at the scalp) SAR: 0.35 W/kg

Exposure 1

Main characteristics

Frequency	450 MHz
Type	electromagnetic field
Exposure duration	"60 s exposure, 60 s recording interval" (this cycle was repeated 10 times)

Modulation

Modulation type	AM
Modulation frequency	7 Hz
Modulation depth	100 %

Exposure setup

Exposure source	signal generator + 13 cm quarter-rhythm antenna
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.

Parameters

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:

human
partial body: left side of the head

Methods Endpoint/measurement parameters/methodology

effects on the neurological system: EEG (comparison of two analysis methods: analysis of the length distribution of low-variability periods (LDLVP) and linear spectral analysis (power spectral density))

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

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:

medical/biological study
experimental study
full/main study
double-blind study

Study funded by

Estonian Science Foundation (ETF), Estonia

Smitha CK et al. (2015): Analysis of fractal dimension of EEG signals under mobile phone radiation
Hinrikus H et al. (2011): Higuchi's fractal dimension for analysis of the effect of external periodic stressor on electrical oscillations in the brain
Suhhova A et al. (2009): Effect of modulated microwave radiation on human EEG asymmetry
Hinrikus H et al. (2009): Effect of modulated at different low frequencies microwave radiation on human EEG
Hinrikus H et al. (2008): Effect of 7, 14 and 21 Hz modulated 450 MHz microwave radiation on human electroencephalographic rhythms
Hinrikus H et al. (2008): Effect of low frequency modulated microwave exposure on human EEG: Individual sensitivity
Suhhova A et al. (2008): Effect of Microwave Radiation on EEG Coherence
Bachmann M et al. (2007): Individual changes in human EEG caused by 450 MHz microwave modulated at 40 and 70 Hz
Bachmann M et al. (2006): Integration of differences in EEG Analysis Reveals Changes in Human EEG Caused by Microwave
Bachmann M et al. (2005): Effect of 450 MHz Microwave Modulated with 217 Hz on Human EEG in Rest
Hinrikus H et al. (2005): Non-Thermal Effect of Microwave Radiation on Human Brain
Hinrikus H et al. (2004): Changes in human EEG caused by low level modulated microwave stimulation