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.
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.
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%.
|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.|
|Exposure duration||continuous for 5, 15, and 50 min|
|power density||10 mW/m²||-||-||-||-|
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.