Medical/biological study (experimental study)

Individual changes in human EEG caused by 450 MHz microwave modulated at 40 and 70 Hz med./bio.

By: Bachmann M, Tomson R, Kalda J, Säkki M, Lass J, Tuulik V, Hinrikus H

Published in: Environmentalist 2007; 27 (4): 511-517

Aim of study (acc. to author)

To study the effect of microwaves modulated at different frequencies (40 and 70 Hz) on human electroencephalographic (EEG) rhythms.

Background/further details

15 subject participated (eight males, 7 females). All subjects passed two EEG recordings on two different days under microwave exposure and sham exposure.

Endpoint

effects on the neurological system: brain activity/EEG

Exposure

- low level microwaves
- PW pulsed wave

Exposure	Parameters
Exposure 1: 450 MHz Exposure duration: 40 min. = 10 cycles of each modulation frequency (1 min. on - 1 min. off)	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	40 min. = 10 cycles of each modulation frequency (1 min. on - 1 min. off)

Modulation

Modulation type	cf. additional info
Additional info	pulse-modulated modulation frequencies: 40 Hz and 70 Hz duty cycle = 50%

Exposure setup

Exposure source	13 cm quarter-wave antenna
Distance between exposed object and exposure source	10 cm
Setup	antenna placed near the left side of the test person'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	-	-	-	-

Reference articles

Bachmann M et al. (2005): Non-linear analysis of the electroencephalogram for detecting effects of low-level electromagnetic fields
Hinrikus H et al. (2004): Changes in human EEG caused by low level modulated microwave stimulation
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 (changes in energy (power spectrum; powers of EEG theta waves, alpha waves, and beta waves), in time variability (analysis of the length distribution of low-variability periods (LDLVP), and in beta ratio (relative difference in power distribution between beta wave & theta wave rhythms inside the EEG))

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

during exposure

Main outcome of study (acc. to author)

450 MHz microwave exposure modulated at 40 Hz caused statistically significant changes in the EEG time variability (i.e. LDLVP) in four subjects (26.7%) and energy variations (increase in energy of beta wave (beta 2) frequency band) in two subjects (13.3%). The LDLVP analysis and relative changes in EEG energy did not detect significant effects of microwave exposure for the whole group.
Statistical evaluation performed for the whole group revealed significant difference between exposed and sham exposed EEG only for the beta ratio (as parameter for energy distribution).
In conclusion, the main trend of changes in the present study was the increase in the EEG beta wave energy and the effect was more evident at the modulation frequency closer to the physiological EEG rhythms (40 Hz).

Study character:

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

Study funded by

Estonian Science Foundation (ETF), Estonia

Hinrikus H et al. (2011): Higuchi's fractal dimension for analysis of the effect of external periodic stressor on electrical oscillations in the brain
Hinrikus H et al. (2009): Effect of modulated at different low frequencies microwave radiation on human EEG
Suhhova A et al. (2009): Effect of modulated microwave radiation on human EEG asymmetry
Hinrikus H et al. (2008): Effect of low frequency modulated microwave exposure on human EEG: Individual sensitivity
Hinrikus H et al. (2008): Effect of 7, 14 and 21 Hz modulated 450 MHz microwave radiation on human electroencephalographic rhythms
Suhhova A et al. (2008): Effect of Microwave Radiation on EEG Coherence
Bachmann M et al. (2006): Integration of differences in EEG Analysis Reveals Changes in Human EEG Caused by Microwave
Bachmann M et al. (2005): Non-linear analysis of the electroencephalogram for detecting effects of low-level electromagnetic fields
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