To examine time dependence effects of exposure to radiofrequency irradiation, emitted by GSM cellular phones, on cognitive functions of humans. The authors aimed to replicate and extend a previous study (publication 12887); especially to examine time-dependency and slowing of the left-hand response as results of the previous study.
48 healthy males (right-handed) were divided into three groups: 1) exposure to the left side of the head, 2) exposure to the right side of the head, 3) sham exposure. All partcipants performed a spatial working memory task (that required either a left-hand or a right-hand response; 12 blocks of 50 trials). By averaging the reaction times separately for each block, the time course of the radiofrequency irradiation effect could be assessed.
three exposure conditions were tested: i) exposure at the left side of the head ii) exposure at the right side of the head iii) sham exposure
|Exposure duration||1 h|
|Pulse width||0.577 ms|
|Duty cycle||12.5 %|
|Repetition frequency||217 Hz|
|Distance between exposed object and exposure source||1.5 cm|
|Setup||two standard Nokia 5110 GSM cellular phones attached to both sides of the head by a nonconductive frame|
|Sham exposure||A sham exposure was conducted.|
During the first two time blocks, the average reaction time of the right-hand responses [matching condition] was significantly longer under left-side exposure than under right-side exposure and sham exposure averaged together. This result confirms an effect of exposure on reaction times. Left-hand responses [mismatching condition] showed the same pattern, but it was non-significant. The participants failed to judge which phone was operating during the experiment.
Although the present results confirmed some findings from the previous study (e.g. time dependency of reaction times), differences between the present results and previous findings may be due to the following factors: exposure duration, responding hand, side of exposure, and differences in the cognitive tasks. These factors may have major influence on the detection of radiofrequency irradiation effects.