Schmid G, Sauter C, Stepansky R, Lobentanz IS, et al. (2005).
There have been a number of studies of the possible effects of cell phone exposure on cognitive function. These have produced varying results. All have used the frequencies of the GSM system. The study by Schmid and colleagues is the first in a peer-reviewed journal that has explored the effect of a signal in the UTMS range.
The authors recruited 58 healthy volunteers, all of whom were regular users of cell phones. Their visual perception was assessed by four different tests while they were exposed to a 1.97 GHz signal. Each subject performed the tests three times in the one session, while subjected to "High Exposure", "Low Exposure", and "Sham Exposure" states. The estimated 10g averaged SAR was 0.37 W/kg in the High Exposure state. The Low Exposure was one-tenth of the High Exposure, and the Sham 100,000 times less than the Low Exposure. The order of exposure was randomly controlled, and the test was double-blinded.
None of the investigated parameters of visual perception showed a statistically significant difference between sham and the two different levels of exposure.
The only other study that has explored the effects of an UTMS-like signal on brain function is that by Zwamborn et al. (2003), who used very low power in their experiment. This study has not yet been published in a peer-reviewed journal (as of June 2005). One of the tests they used was of selective visual attention, and they reported statistically significant differences in exposed subjects. Schmid and colleagues have no explanation for the contrast in their findings from those of Zwamborn et al.