Authors

Carrubba S, Frilot C 2nd, Chesson AL Jr, Marino AA. Mobile-phone pulse triggers evoked potentials. Neurosci Lett. Dec 3, 2009. Ahead of print.

Background
Mobile phones transmit and receive high-frequency electromagnetic fields (EMFs) and also emit low-frequency magnetic pulses from the phone’s circuitry and battery currents.  If exposure to mobile phones is hazardous, the authors hypothesize that processes or mechanisms exist that allow the body to detect at least one field. This could explain the adverse health effects associated with mobile phone use found in some studies.

Objective
The aim of this study was to measure brain electrical activity in the form of evoked potentials (EPs) elicited by EMFs produced by mobile phones.

Methods
Participants in this study were 20 clinically normal volunteers (7 males, 13 females) ranging from 18-62 years of age. Mobile phones emit a complicated sequence of electromagnetic, acoustic, thermal, and tactile stimuli. To remove the potential confounding effects of these stimuli, a simulated mobile phone pulse was used in the experiment.  The simulated signal was based on a realistic phone use scenario.  The simulated mobile phone pulse was generated by 2 metal plates located on each side of the subject’s head. The pulse was emitted for 0.7 millisecond with 2.9993 seconds between pulses, resulting in 3 second trials. Subjects were exposed in an isolation chamber to reduce the confounding effect of random stimuli in their environment.  Evoked potentials were recorded by electroencephalograms (EEGs) using electrodes attached to the scalp.  Following an acclimation period, there were two experimental periods consisting of at least 50 trials each during which either a field or a sham field was presented.  The order of presentation of the field and sham varied randomly from subject to subject while they were blind to the exposure condition.

Results
A stimulus equivalent to a pulse produced by mobile phones resulted in statistically significant effects on brain electrical activity in 18 of 20 subjects. Comparable changes were not observed under sham conditions.

Interpretation and Limitations
Several considerations suggest that the changes in brain activity were true evoked potentials.  The analysis used by the authors reduced the probability that the findings were due to chance and the changes occurred several hundred milliseconds after the pulse, which is consistent with the changes arising from brain processing of signals that resulted from the pulse.  In their analysis, the authors also filtered out a certain type of brain response (called alpha energy), which increased their ability to detect evoked potentials. This means that the area of the brain from which alpha energy originates, usually the cerebral cortex, was not crucial in the brain processing that gave rise to the evoked potentials and is consistent with the subjects’ not knowing that the mobile phone field was present, even though the subjects’ brain did. This study was unable to address where in the body the electrical pulse from a mobile phone was detected.  This study is also limited by the use of a simulated rather than an actual mobile phone pulse as the stimulus.

Conclusions
This study found that a pulse of the type produced by mobile phones was detected by 90% of the subjects in the form of evoked potentials. The authors suggest that chronic changes in brain electrical activity may cause or promote disease.



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