Medical/biological study (experimental study)

Mobile phone headache: a double blind, sham-controlled provocation study med./bio.

By: Oftedal G, Straume A, Johnsson A, Stovner LJ

Published in: Cephalalgia 2007; 27 (5): 447-455

Aim of study (acc. to author)

To study whether exposure to radiofrequency electromagnetic fields from mobile phones would result in more headache or discomfort than sham exposure and to test possible effects on physiological parameters such as heart rate and blood pressure.

Background/further details

17 eligible individuals, who experienced symptoms (symptoms to mobile phones, but not to electromagnetic fields in general) in a provocation test, took part in the study.

Endpoint

effects on the neurological system: headache

Exposure

- mobile communications
- digital mobile phone
- GSM

Exposure	Parameters
Exposure 1: 902.4 MHz Modulation type: pulsed Exposure duration: continuous for 30 min	SAR: 1 W/kg cf. remarks (1 g) (spatial peak) SAR: 0.8 W/kg average over mass (10 g)

General information

Seventeen subjects took part in a double-blind, randomized provocation study with cross-over design. Sixty-five pairs of sham and mobile phone RF exposures were applied. Each subject was allowed to take part in a maximum of four randomized pairs of trials, at least 2 days apart, among which, the RF session came first twice. A test session lasted almost 2 h, allowing for an adaptation and rest period.

Exposure 1

Main characteristics

Frequency	902.4 MHz
Type	electromagnetic field
Exposure duration	continuous for 30 min

Modulation

Modulation type	pulsed
Duty cycle	12.5 %
Repetition frequency	217 Hz

Exposure setup

Exposure source	cellular phone GSM, power amplifier
Distance between exposed object and exposure source	8.5 cm
Chamber	The exposure system was the same as in [Wilen et al., 2006]. The exposure equipment, except for the antennas, was placed in a control room next to the shielded exposure room. The subjects were comfortably seated while looking at videos showing nature and wildlife films.
Setup	Two wall-mounted base station antennas [Huber et al., 2003] were mounted symmetrically at 8.5 cm from the sides of the subject's head, the movements of which were restricted sideways by wooden bars.
Sham exposure	A sham exposure was conducted.
Additional info	A power divider directed a part of the signal to one of the antennas or to an ohmic load (sham exposure) and another part to a power meter. The exposure was given on the subject's preferred side or selected by chance.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	1 W/kg	cf. remarks	-	1 g	spatial peak
SAR	0.8 W/kg	average over mass	-	10 g	-

Additional parameter details

The maximum background level of RF signals from GSM base stations was -105 dBm in the exposure room. For an hour after the exposure, the subjects were in an adjacent room where the maximum signal level was -78 dBm.

Measurement and calculation details

The SAR was relatively uniformly distributed over a large area around the ear [Wilen et al., 2006].

Reference articles

Wilen J et al. (2006): Psychophysiological tests and provocation of subjects with mobile phone related symptoms
Huber R et al. (2003): Radio frequency electromagnetic field exposure in humans: Estimation of SAR distribution in the brain, effects on sleep and heart rate

Exposed system:

human
partial body: head

Methods Endpoint/measurement parameters/methodology

effects on the cardiovascular system: heart rate, blood pressure
effects on the neurological system: headache (visual analog scale; questionnaire about symptoms); exposure perception (questionnaire)

Investigated system:

investigation on living organism

Investigated organ system:

Time of investigation:

before exposure
during exposure
after exposure

Main outcome of study (acc. to author)

The data gave no evidence that radiofrequency electromagnetic fields from mobile phones may cause headache or discomfort or influence physiological variables (heart rate, blood pressure).

Study character:

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

Study funded by

NetCom, Norway
Norwegian Post and Telecommunication Authority (NPT), Norway
Norwegian Tele- and Informations Users Group (NORTIB)
Research Council of Norway
Statnett, Norway
Telenor, Norway

Comments on this article

Oftedal G et al. (2011): Response to 'Comment on mobile phone headache: a double-blind, sham-controlled provocation study'
Chu MK (2010): Comment on 'Mobile phone headache: a double blind, sham-controlled provocation study'

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