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May Affect Brain Activity
Cellular phones emit pulsed high-frequency electromagnetic fields that may affect the electrical activity in the human brain in certain situations, according to a study in the October 5th issue of the journal Neuroreport.
But German researchers report that the health effects of their findings are unclear.
Such phones have not been found to have an impact on EEG (electroencephalogram) traces, the method used to measure brain electrical activity. However, in the new study, 13 healthy men in their 20s were asked to press a button when they heard certain high-frequency tones in a series of tones emitted every 2 seconds. During the study, a mobile phone was mounted to the study subject's head, but the subject did not know when the phone was switched on. While the men were engaged in the task set, EEG readings were recorded from 30 positions on the scalp.
After the test was performed several times, the EEG results were averaged and the researchers found that exposure to an active cellular phone appeared to influence electrical activity in the left hemisphere of the brain, that closest to the phone. But this effect was only noted when the brain was engaged in the task set. No such effect was seen when the subjects listened to tones not related to the button-pushing task, report Dr. Carsten Eulitz of the University of Konstanz and colleagues in Berlin, Germany.
``This gives further evidence to the possibility that neural responses as reflected in the EEG can be modulated through radiation emitted by mobile phones,'' they write.
But it is not clear what, if any, effect the phones may have on health, the researchers note.
``This study does not allow us to determine any health risk, nor is it clear what behavioral consequences PEMF (pulsed high-frequency electromagnetic fields) exposure might have,'' they conclude. SOURCE: Neuroreport 1998;9:3229-3232.