Effects of extremely low frequency electromagnetic fields on transient evoked otoacoustic emissions in rabbits

Abstract

Objective: Humans are continuously exposed to an extremely low frequency (ELF) of electromagnetic fields (EMF), transmitted from the common sources like power stations, electric transmission lines, communication and radio-television signal transmission units. The present study aimed to assess the effects of 5.068 kV/m and 10.182 kV/m electric fields, which refer to the lower and upper intensity limits beyond which hazardous effects can be observed, on the auditory functions of rabbits via transient evoked otoacoustic emission (TEOAE) recordings. Methods: The study was performed on 20 healthy adult female New Zealand White rabbits randomly divided into two groups and applied either 5.068 kV/m (Group 1) or 10.182 kV/m (Group 2) of electric field for 3 h/day for 14 days. TEOAE responses were recorded on day 0 before the exposure (0-BE) and on the 6th (6th-AE) and 14th (14th-AE) days after the exposure (AE). Emission amplitudes at 1.0-4.0 kHz were analyzed. Results: In Groups 1 and 2, the amplitudes separately recorded on the 6th-AE day were not different from the amplitudes recorded on day 0-BE. On the 6th-AE day, the only significant difference was detected in the right ear recordings of Group 1 at the frequency of 1.5 kHz (p = 0.007). In Group 1, at 1.5 kHz, the median 6th day AE value (3.8 dB SPL) for the right ear was significantly tower than the median BE value. No significant difference in terms of amplitudes was detected in the comparison of 14th day AE with day 0-BE recordings. In the comparison of the groups for the recordings obtained at all the time points, no statistically significant differences were found. Conclusion: It was concluded that the TEOAE decrease at 1.5 kHz of the right ears of Group I on the 6th day AE was transient; and on the 14th day AE, no significant decrease was determined in the TEOAEs of both groups. Our results showed that the ELF EMFs have no significant effects on the hearing sensation of rabbits, the cochlear functions of whose were evaluated using TEOAE recordings. (C) 2008 Elsevier Ireland Ltd. All rights reserved.