Medical/biological study (experimental study)

902 MHz mobile phone does not affect short term memory in humans. med./bio.

By: Haarala C, Ek M, Bjornberg L, Laine M, Revonsuo A, Koivisto M, Hämäläinen H

Published in: Bioelectromagnetics 2004; 25 (6): 452-456

Aim of study (acc. to author)

To study the effects of an electromagnetic field as emitted by a 902 MHz mobile phone on human short term memory.

Background/further details

The study was a replication with methodological improvements (multi-centre testing and a double-blind study design) to a previous study (publication 4728). A total of 64 subjects in two independent laboratories performed a short term memory task.

Endpoint

cognitive/behavioral endpoints: short term memory

Exposure

- mobile communications
- GSM

Exposure	Parameters
Exposure 1: 902 MHz Modulation type: pulsed Exposure duration: continuous for 65 min	SAR: 2.07 W/kg maximum SAR: 0.99 W/kg average over mass (10 g) power: 0.25 W mean

Exposure 1

Main characteristics

Frequency	902 MHz
Type	electromagnetic field
Exposure duration	continuous for 65 min

Modulation

Modulation type	pulsed
Pulse width	577 µs
Repetition frequency	217 Hz
Additional info	Discontinuous transmission mode was not activated.

Exposure setup

Exposure source	cellular phone
Distance between exposed object and exposure source	0.0337 m
Setup	The mobile phone was mounted on the left side of the subject's head in the normal position of use with an adjustable rubber head cap. The antenna was located over the left posterior temporal lobe. The distance from the surface of the skull was measured in 12 randomly selected subjects, averaging 33.7 mm (SD 2.57 mm).
Additional info	Each subject performed the tasks twice, once under the exposure to a mobile phone and once under a sham exposure. These sessions were separated by 24 ± 1 h. Both the subjects and the experimenters were unaware of the exposure condition (double blind).

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	2.07 W/kg	maximum	measured	-	-
SAR	0.99 W/kg	average over mass	measured	10 g	-
power	0.25 W	mean	-	-	-

Measurement and calculation details

The SAR of the phone was measured using SPEAGs Dosimetric Assessment System 3 (DASY3) and a generic twin phantom filled with brain tissue simulating liquid.

Exposed system:

human
partial body: head (left side)

Methods Endpoint/measurement parameters/methodology

cognitive/behavioral endpoints: short term memory, working memory load (performance in sequential letter memory tasks; memory load was varied from 0-3 items in a n-back task) (reaction time; accuracy of responses)

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

during exposure

Main outcome of study (acc. to author)

No statistically significant differences in performance between the two laboratories were found. The authors could not replicate the previous results: the electromagnetic field had no effect on reaction times or on the accuracy of the subjects' answers. The inability to replicate previous results could have been caused by lack of actual electromagnetic field effects or the magnitude of effects being at the sensitivity threshold of the test used.

Study character:

Study funded by

Nokia
University of Turku, Finland
Elisa Communications Corporation, Finland
Benefon, Finland
Sonera, Finland
Tekes (National Technology Agency), Finland
Finnet Networks Ltd., Finland

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