Medical/biological study (experimental study)

Effects of thirty minutes mobile phone use on the human sensory cortex med./bio.

By: Yuasa K, Arai N, Okabe S, Tarusawa Y, Nojima T, Hanajima R, Terao Y, Ugawa Y

Published in: Clin Neurophysiol 2006; 117 (4): 900-905

Aim of study (acc. to author)

To study whether the pulsed radiofrequency electromagnetic field emitted by a mobile phone for 30 min has short-term effects on human somatosensory evoked potentials.

Endpoint

effects on the neurological system: somatosensory evoked potentials (SEP)

Exposure

- TDMA
- mobile communications
- digital mobile phone

Exposure	Parameters
Exposure 1: 800 MHz Modulation type: pulsed Exposure duration: continuous for 30 min	power: 0.8 W peak value (simulator-controlled) power: 0.27 W mean (simulator-controlled) SAR: 0.054 W/kg average over mass (10 g) (± 0.02 W/kg, in the brain)

Exposure 1

Main characteristics

Frequency	800 MHz
Type	electromagnetic field
Exposure duration	continuous for 30 min

Modulation

Modulation type	pulsed
Pulse width	6.7 ms
Duty cycle	33.5 %
Repetition frequency	50 Hz
Additional info	usual Japanese mobile phone signal: π/4 shifted QPSK and 3 channel TDMA with a frame period of 20 ms and time slots of 6.7 ms

Exposure setup

Exposure source	cellular phone handset connected to a communication tester, at maximum output power
Distance between exposed object and exposure source	4 cm
Setup	The handset was oriented in the normal use position over the right ear with the antenna located about 4 cm from head.
Sham exposure	A sham exposure was conducted.
Additional info	Since the subjects were unable to hold the phone at a fixed position during the experiment, the SAR in the brain was not mathematically constant.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power	0.8 W	peak value	cf. remarks	-	simulator-controlled
power	0.27 W	mean	cf. remarks	-	simulator-controlled
SAR	0.054 W/kg	average over mass	measured	10 g	± 0.02 W/kg, in the brain

Measurement and calculation details

SAR at the brain area (3 cm below the skull under the coil) was measured using a phantom system recommended by the IEC standard, with the handset fixed at different positions which did, however, not yield significantly different results.

Exposed system:

human
partial body: head (right ear)

Methods Endpoint/measurement parameters/methodology

effects on the neurological system: somatosensory evoked potentials (single pulse SEP recording (amplitudes and latencies); recovery function)

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

before exposure
after exposure

Main outcome of study (acc. to author)

30 min mobile phone use had no short-term effects on the human sensory cortex. Neither somatosensory evoked potentials nor their recovery function was affected by exposure.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Association of Radio Industries and Businesses (ARIB), Japan
Committee to Promote Research on the Possible Biological Effects of Electromagnetic Fields, Japan
Ministry of Internal Affairs and Communications, Japan

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