Medical/biological study (experimental study)

Human brain activity during exposure to radiofrequency fields emitted by cellular phones med./bio.

By: Hietanen M, Kovala T, Hämäläinen AM

Published in: Scand J Work Environ Health 2000; 26 (2): 87-92

Aim of study (acc. to author)

To explore the possible influence of radiofrequency fields (emitted by 5 different cellular phones) on human brain functions.

Endpoint

effects on the neurological system: EEG

Exposure

- mobile communications
- analog mobile phone
- digital mobile phone
- GSM
- NMT

Exposure	Parameters
Exposure 1: 900–1,800 MHz Exposure duration: repeated exposure trials for 30 min with 20 min of real exposure	power: 2 W (1-2 W) SAR: 850 mW/g (0.851-0.818 mW/g)

Exposure 1

Main characteristics

Frequency	900–1,800 MHz
Type	electromagnetic field
Exposure duration	repeated exposure trials for 30 min with 20 min of real exposure
Additional info	Four mobile phones operated at 900 MHz and one at 1800 MHz.

Modulation

Modulation type	cf. additional info
Additional info	NMT, GSM, or PCN

Exposure setup

Exposure source	cellular phone see setup details
Distance between exposed object and exposure source	1 cm
Setup	Three different analogue 900 MHz NMT phones were used with either a helix, fixed whip, or extended whip antenna as well as two digital phones operating at 900 MHz (GSM) and at 1800 MHz (PCN), respectively. The phones were operated via a computer and without sound transmission (single-blind). The phones which were not held by the test persons were located 1 ± 0.5 cm from the head while the subjects were seated in a comfortable chair.
Additional info	Five exposure trials of 30 min were performed each with 20 min of RF exposure and 5 min of sham exposure before and after the real exposure. Apart from this there was a separate 30 min sham exposure trial. The order of different exposure conditions was randomised. Only one test per day was done for each subject.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power	2 W	-	-	-	1-2 W
SAR	850 mW/g	-	measured and calculated	10 g	0.851-0.818 mW/g

Measurement and calculation details

The functioning of the phones was checked with a power meter at the start and occasionally during the trials. Electric fields inside a liquid phantom head were measured with and without the EEG electrodes attached using an electric field probe, and the calculated SAR values were nearly the same in both cases.

Exposed system:

human
partial body: head

Methods Endpoint/measurement parameters/methodology

effects on the neurological system: EEG activity (absolute power) in awake, closed-eyes situation

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

during exposure

Main outcome of study (acc. to author)

Radiation to one of the phones caused a statistically significant change in the absolute power at the delta band of the EEG recording. However, no difference was found in the relative power of the same band, and no changes occured during radiation to other phones at any frequency bands. The data suggest that exposure to radiofrequency field emitted by cellular phones has no abnormal effects on EEG activity. The observed difference in one parameter was probably caused by statistical chance.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Tekes (National Technology Agency), Finland

Comments on this article

Harma M (2000): Electric hypersensitivity and neurophysiological effects of cellular phones - facts or needless anxiety?

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