Medical/biological study (experimental study)

Long-Term Evolution electromagnetic fields exposure modulates the resting state EEG on alpha and beta bands med./bio.

By: Yang L, Chen Q, Lv B, Wu T

Published in: Clin EEG Neurosci 2017; 48 (3): 168-175

Aim of study (acc. to author)

The effects of exposure to 2.61 GHz electromagnetic field (LTE) on the human EEG should be investigated.

Background/further details

The results of a previous study on brain activity by the authors (Lv et al. 2014) should be confirmed using another method.
25 healthy male volunteers participated in 2 sessions, which were separated by 1 week. Each session lasted 50 minutes and comprised 5 time slots at 10 minutes. In the first (pre-exposure) and last slot (post-exposure), EEG was always measured without EMF exposure. The 3 intermediate slots were either used for EMF exposure in one random session or for sham exposure in the other.
All subjects were moderate mobile phone users (voice communication for less than 30 minutes per day) and none used a mobile phone for more than 10 minutes during the day prior to the experiments.

Endpoint

effects on the neurological system: resting EEG

Exposure

- 2.61 GHz
- mobile communications
- mobile phone
- LTE

Exposure	Parameters
Exposure 1: 2.61 GHz Exposure duration: continuous for 30 minutes	SAR: 1.34 W/kg peak value (10 g) (with electrodes) SAR: 1.96 W/kg peak value (1 g) (with electrodes) power: 0.25 W peak value (power delivered to the dipole antenna)

Exposure 1

Main characteristics

Frequency	2.61 GHz
Type	electromagnetic field
Exposure duration	continuous for 30 minutes
Additional info	LTE

Modulation

Modulation type	cf. additional info
Additional info	applied radio frame (10-ms total length) consisted of 2 half-frames of equal length; each half-frame comprised 5 subframes, each 1 ms in length; maximum emission configuration was used (6 uplink subframes in the radio frame); radiation duration (including the uplink subframes and uplink pilot time slot special subframes) accounted for 63.3% of the total length of the frame

Exposure setup

Exposure source	dipole antenna anechoic chamber signal generator
Distance between exposed object and exposure source	1 cm
Setup	subjects were in sitting position with eyes closed; plastic spacer of 1 cm was used to maintain the distance between the right ear and a standard dipole
Sham exposure	A sham exposure was conducted.
Additional info	right ear was exposed because subjects were assumed to be right-hand dominant

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	1.34 W/kg	peak value	calculated	10 g	with electrodes
SAR	1.96 W/kg	peak value	calculated	1 g	with electrodes
power	0.25 W	peak value	-	-	power delivered to the dipole antenna

Additional parameter details

power delivered to the dipole was equivalent to a theoretical maximum emission by an LTE terminal and below the current safety limit; according to simulated SAR values, the maximum resultant temperature increase was not more than 0.1°C

Measurement and calculation details

SAR was simulated using a human head model with and without EEG electrodes

Exposed system:

human
partial body: right ear

Methods Endpoint/measurement parameters/methodology

effects on the neurological system: resting EEG (power and inter-hemispheric coherence of delta waves, theta waves, alpha waves and beta waves in 10 brain regions; interference of the EMF signals on the EEG was ruled out with EEG measurements on a watermelon)

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)

Exposure to the electromagnetic field significantly reduced the power and inter-hemispheric coherence of alpha waves and beta waves in the frontal and temporal brain regions during and after exposure in comparison to the sham exposure and compared to the pre-exposure condition. No significant change was observed in the power or the inter-hemispheric coherence of brain waves in different time slots during and after the exposure.
Results for delta waves and theta waves were not presented.
The authors conclude that exposure to a 2.61 GHz electromagnetic field (LTE) might modulate alpha waves and beta waves in the human EEG, supporting previous results.

Study character:

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

Study funded by

National Key Basic Research Project, China
National Natural Science Foundation (NSFC), China

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