Luria R, Eliyahu I, Hareuveny R, Margaliot M, Meiran N (2009) Cognitive effects of radiation emitted by cellular phones: The influence of exposure side and time. Bioelectromagentics EPub November 17 2008.
Background and Objective
This study examined the time dependence of effects of radiofrequency (RF) exposure emitted by standard GSM cellular phones on cognitive functioning. The authors sought to replicate and extend previous findings concerning what was found to be a large effect due to the sidedness of RF exposure on spatial tasks.
Forty-eight healthy male subjects were randomly divided into three exposure conditions: (1) left-side of the head, (2) right-side, or (3) sham (counterbalanced) exposure. Only right-handed subjects were used, since they show greater hemispheric specialization than left-handed subjects. Each subject had two standard GSM phones attached, one on each side of the head. Phones operated at either no-transmission or full-power transmission (890.2 MHz, which averaged over pulsed frequencies to 0.25 W power). The maximum specific absorption rate reported for these Nokia models ranged from 0.54 to 1.09 W/kg. Phones were silent during the testing. The cognitive task involved spatial working memory, measuring the reaction time to identify whether an image appeared in the same location as a previously viewed image.
On average, there was an improvement of 88 ms from the first test to the last test (indicating the effect of practice), and right-hand responses were 50 ms faster than left-hand responses. RF exposure statistically slowed reaction times in right-hand responses during left-side exposure only, although the right-side and sham exposures showed comparable reaction time patterns (this was only during the first two of twelve blocks of trials). Left-hand responses also showed similar patterns, but they were weaker and not statistically significant. Accuracy of response was higher at the end of the testing compared to the beginning, but the authors did not find any effect of RF exposure on accuracy.
Interpretation and Conclusion
The authors interpret the result to confirm the existence of an effect of exposure on reaction time, which replicates earlier work. The study also demonstrated that RF exposure effects may be time dependent, being observed only at specific phases of the experiment. While the authors acknowledge that there is no explanation for the existence of cognitive effects of cellular phones, especially not for their possible attenuation over time, the present results may point toward a possible mechanism involving cognitive tasks governed by initial practice and learning processes.