Galloni P, Lopresto V, Parazzini M, Pinto R, Piscitelli M, Ravazzani P, Marino C. No effects of UMTS exposure on the function of rat outer hair cells. Bioelectromagnetics Feb 25, 2009 Ahead of print.
The hearing system, due to its physical position, can be involved in interactions with electromagnetic fields (EMFs) emitted by mobile phones. The cochlear sensory structure, in particular the hair cells, is sensitive to various exogenous agents.
The aim of this article is to describe the results of the study on potential effect of UMTS EMFs on outer hair cells (OHC) functionality in laboratory animals.
A total of 60 male Sprague-Dawley rats were used in the experiment. A total of 24 animals were locally exposed (right ear) to 1946 MHz UTMS EMFs at SAR level of 10 W/kg, 2 hours a day, 5 days a week, for 4 weeks, and 24r animals were sham exposed. A total of 24 rats (positive control) were injected with an ototoxic antibiotic kanamycin (KM). Rats were tested by recording Distortion Product Otoacoustic Emissions (DPOAE). DPOAE recordings were performed before exposure, at the end of each exposure week, and one week after the last exposure day, for a total of 6 test sessions. All procedures were in blind for the operator. In addition, 8 rats in the exposed group and 8 sham exposed rats were subjected to additional DPOAE recordings up to a total of 14 consecutive measurements to obtain data on the progression in time of potential effects of UMTS exposure.
The trends of DPOAE amplitudes across the recording sessions were the same for the exposed and sham groups of rats. This observation was confirmed by the statistical analyses, which has shown that neither the exposure condition (between-subject factor) nor the interaction between the day of testing and the exposure condition were significant (P>0.05), for all the tested frequencies and stimulus levels. The day of testing (within-subject factor) was occasionally significant in some DPOAE frequencies, but this variability was observed in both groups of animals. The DPOAE amplitudes were significantly decreased in KM-treated rats (positive control). This effect starts 4 weeks after the antibiotic injection and, as expected, is clearly marked at higher frequencies. In the 16 animals subjected to additional DPOAE recordings, all the differences between the exposed and the sham groups were in the range of physiological variation; no statistically significant differences were found for both the exposure factor and the time-exposure interaction. DPOAE recordings from KM-treated animals show the same behavior in closer measurement sessions.
Interpretation and conclusion
A small number of experiments dealt with potential effects of UMTS exposure on central nervous system related endpoints in animals. Some studies investigated effects of GSM-like exposures. No effects were found by the authors in their previous experiments or by other investigators on the auditory system in animals even though the animals were exposed to SAR values (1-10 W/kg) far above the levels related to mobile phone use. None of the measures of the auditory function studied in healthy humans was affected by exposure to EMFs from mobile phones. This is the first study specifically addressing the effect of UTMS EMFs on outer hair cells function in laboratory animals. Despite the high level of localized SAR (10 W/kg), no statistically significant effect of EMF at UMTS frequency was found on hearing function of rats assessed by measurement of DPOAEs.