Krause CM, Haarala C, Sillanmaki L, Koivisto M, et al. (2004)

The aim of this study was to replicate an earlier study by the same authors in 2000. The only differences on this occasion were that the present study was double blind and the phone was attached to the left side of the subject's head, rather than the right side.

Twenty-four (12 male) healthy volunteers performed an auditory memory task. Each test period was subdivided into 2 segments, one with the EMF turned off and the other with the EMF on. The EMF exposure order was counterbalanced so that half the subjects had the EMF exposure first. Neither the subject nor the investigator was aware of the status of the exposure. Electroencephalographic (EEG) tracings were recorded during the testing procedures.

The EMF was from a 902 MHz phone, pulsed with a frequency of 217 Hz and a pulse width of 0.557 msec. The SAR value averaged over 10 g of tissue was 0.648 W/kg.

The mean percentage of incorrect answers for EMF was significantly increased. This had not been the case in the authors' earlier study.

The authors found that they could not replicate the EEG results they obtained in the previous study. All of the eight significant changes in the earlier study were not significant in the present one. In the 2000 study, EMF significantly modulated the EEG in all studied frequency bands (4-12 Hz), whereas in the present study changes were only seen in the 4-6 and 6-8 Hz bands. In the 6-8 Hz band the magnitude of the event-related synchronization (ERS) responses was significantly reduced in the present study, while they were increased in the 8-10 Hz band in the 2000 paper. The changes were seen most strongly in the left hemisphere. In the earlier paper this unilaterality was not seen. In the 4-6 band EMF exposure decreased both the initial ERS response and the subsequent event-related desynchronization responses.

The authors could not explain the different results between the two studies.

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