Authors

Kaprana AE, Chimona TS, Papadakis CE, Velegrakis SG, Vardiambasis IO, Adamidis G, Velegrakis GA. Auditory Brainstem Response Changes during Exposure to GSM-900 Radiation: An Experimental Study. Audiol Neurootol.16(4):270-276. Nov 16, 2010. Ahead of print.

Introduction
The ear is the anatomical structure closest to the mobile phone use. Possible effects of mobile phone radiation on the auditory system, in particular electrophysiological changes, have been investigated in many studies. So far, no clear evidence of an effect on auditory brainstem and cochlear responses has been obtained in studies comparing post-exposure electrophysiological recordings to baseline recordings. To the authors’ knowledge, there have been no studies of time-related electrophysiological changes in the auditory system during exposure to radiofrequency radiation from mobile phones.

Objective
The objective of this study was “to investigate the possible electrophysiological time-related changes in auditory pathway during mobile phone EMF exposure”.

Methods
Twenty eight New Zealand rabbits with normal auditory function (as confirmed by otoscopy and baseline auditory brainstem response (ABR) measurements) were exposed to non-modulated continuous-wave 903 MHz signal for 60 minutes. The total average output power of the transmitter was ~0.22 W, a typical value of the average power transmitted by a mobile phone under favorable conditions near a base station. ABRs (absolute wave latency and inter-wave latency) were measured ipsilaterally to the exposed ear at 1, 15, 30, 45 and 60 minutes of exposure, and contralaterally at 60 minutes of exposure. ABRs were also measured 24 hours post-exposure.
 
Results
Four positive waveforms (waves I-IV) were clearly seen at baseline, and wave V was detected less frequently and only at higher levels of auditory stimulus. For ipsilateral ears, significant delay in mean absolute latencies (compared to baseline recordings) was observed for waves III, IV and V at 60, 45 and 15 minutes of exposure, respectively. At 60 minutes of exposure, mean inter-wave latency I-III was prolonged in accordance with wave III delay. Mean inter-wave latencies I-V and III-V were significantly prolonged at 30 minutes. ABR measurements returned to baseline values 24 hours post-exposure. For contralateral ear, no statistically significant changes compared to baseline ABR recordings were seen at 60 minutes.

Interpretation and Conclusion
These findings suggest that “exposure to EMF emitted by mobile phone can affect the normal electrophysiological activity of the auditory system”. The observed responses “fit the pattern of general responses to a stressor”. The authors point out that, because of differences in brain structure and anatomy between animals and humans, neurological data from animal experiments cannot be safely extrapolated to humans. Also, “waves of various forms and characteristics” are emitted during mobile phone use, which should be taken into consideration in studies of potential neurological effects.


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