Study type: Medical/biological study (experimental study)

Does short-term exposure to mobile phone base station signals increase symptoms in individuals who report sensitivity to electromagnetic fields? A double-blind randomized provocation study. med./bio.

Published in: Environ Health Perspect 2007; 115 (11): 1603-1608

Aim of study (acc. to author)

This in vivo study was performed to determine whether the short-term exposure to base station-like signals causes negative health effects in humans.

Background/further details

56 participants in the so called "electrosensitive group" (self-reported experience of negative health effects from electromagnetic field exposure) and 120 participants in the control group were tested in the open provocation study (both participants and experimenters knew the base station status). Of these, 44 electrosensitive and 115 controls completed also the double-blind study.
The study was carried out in four sessions: first session both open and double-blind, second to fourth session only double-blind.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 886.8–1,879 MHz
Modulation type: pulsed
Exposure duration: continuous for 5, 15, and 50 min
Exposure 2: 2,020 MHz
Exposure duration: continuous for 5, 15, and 50 min

General information

Each participant attended four testing sessions at least one week apart. Sessions 2, 3, and 4 each used a single exposure condition (GSM, UMTS, or sham) double-blind, random, and counterbalanced. Session 1 took about 3 hours to complete while sessions 2, 3, and 4 each took about 1.5 hours.

Exposure 1

Main characteristics
Frequency 886.8–1,879 MHz
Type
Exposure duration continuous for 5, 15, and 50 min
Additional info combined signal of both 900 and 1800 MHz bands containing both broadcast and traffic channels at 886.8, 888.8, 1877, and 1879 MHz
Modulation
Modulation type pulsed
Additional info

GSM signal consisting of 8 timeslots, each with a duration of 576.875 µs resulting in a total frame duration of 4.615 ms, and interslot guard intervals of 32 µs duration with a drop in power level of around 50 dB. The 8 time slots on the broadcast channels were always occupied, while changes in the power level of the traffic channels were simulated using two first order, two state Markov processes, assuming a blockage rate of 1% and call activity of 40%.

Exposure setup
Exposure source
Distance between exposed object and exposure source 5 m
Chamber The testing room was 7 m x 4 m x 2.4 m and had a shielding effectiveness > 60 dB at the tested frequency range.
Setup Participants were seated 5 m from the base station antenna, which was hidden by a screen at 2.8 m, upon which instructions were projected from outside the testing room through a screened window.
Sham exposure A sham exposure was conducted.
Additional info In session 1, wash-out periods of 2 min were inserted between exposures.
Parameters
Measurand Value Type Method Mass Remarks
power density 10 mW/m² - - - combined signal (2x 5 mW/m²)

Exposure 2

Main characteristics
Frequency 2,020 MHz
Type
Exposure duration continuous for 5, 15, and 50 min
Modulation
Modulation type cf. additional info
Additional info

UMTS signal with traffic modelling using Test Model 1, as defined by the 3GPP standard, with high peak to average ratio power changes.

Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power density 10 mW/m² - - - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated material:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

During the open provocation, electrosensitive individuals reported lower levels of well-being in both the GSM and UMTS exposures compared to sham exposure, while the control group reported more symptoms during the UMTS exposure.
During double-blind tests the GSM exposure did not have any effect on either group. The electrosensitive group reported elevated levels of arousal during the UMTS exposure, while the number or the severity of symptoms experienced did not increase.
The short-term exposure to a GSM base station-like signal did not affect well-being or physiological functions in electrosensitive or normal individuals.

Study character:

Study funded by

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