A group of 22 students was tested for their thermal pain threshold by heat stimulation of two fingers. Temperature was increased at a rate of 5°C per second. The probands performed the test two times, divided by one week. Hence, every proband was UMTS and sham exposed, but not aware of the order. Every proband performed 5 blocks of testing at one day of the experiment, every block consisting of 3 trials per finger: 1.) control block, 2./3.) block during the exposure/sham exposure period (at the beginning and at the end), 4.) block 30 minutes after the exposure/sham exposure period and 5.) block 60 minutes after the exposure/sham exposure period.
Before UMTS-exposure, the heat stimulation device was validated in a positive control, using another group of students, where thermal pain was induced by topical capsaicin (component of chili peppers, produces a sensation of burning on the skin) treatment.
Exposure duration: continuous for 30 minutes
|Exposure duration||continuous for 30 minutes|
|Setup||exposure device was based on a dual-band patch antenna (31 mm diameter, 0.5 mm thick; incapsulated in a 40 mm diameter, 7 mm thick (1 mm at application side) transparent plastic capsule with styrofoam isolation) attached to a UMTS mobile phone connected by a serial cable to a personal computer and controlled by software; patch antenna was mounted on a plastic headset next to the right ear, mimicking the normal use of mobile phones|
|Sham exposure||A sham exposure was conducted.|
The exposure caused a measurable desensitization effect through significantly increasing the thermal pain threshold on the contralateral side of exposure. In parallel, the subjective pain perception increased in the block at the end of the irradiation (block 3) for the sham exposure condition. Altogether, the data indicate that the overall subjective sensitization to repeated thermal stimulation was attenuated in the UMTS exposure group.