Effects of extremely low frequency electromagnetic fields on distortion product otoacoustic emissions in rabbits.
OBJECTIVE
Humans are continuously exposed to extremely low frequency (ELF), 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 50 Hz ELF-EMF of 5.068 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 Distortion Product Otoacoustic Emission (DPOAE) recordings.


METHODS
The study was performed on 20 healthy adult female New Zealand White rabbits randomly divided into two groups and applied 50 Hz ELF-EMF with either 5.068 kV/m (Group 1) or 10.182 kV/m (Group 2) of electric field for 3h/day during 14 days. DPOAE responses recorded on the 0th day before exposure (B-EMF) and on the 6th (A-EMF-6th) and 14th (A-EMF-14th) days after exposure (AE). Mean stimulus intensity and emission amplitudes at 1.0-8.0 kHz were analyzed.


RESULTS
In Group 2 rabbits, on 6th and 14th days, the DPOAE amplitudes were observed as increased at 1.5-4.0 kHz (at 2.0 and 4.0 kHz significantly) than B-EMF values. At 6.0 kHz, A-EMF-14th amplitudes were significantly lower than A-EMF values.


CONCLUSIONS
These results suggest that ELF EMFs might affect hearing functions by frequency dependent manner. Higher ELF EMFs exposure caused increase of cochlear activity. Ototoxic effect of 10.182 kV/m ELF EMFs may begin at the basal turn of the cochlea by reducing DPOAEs at high frequencies.
Budak
Bilgehan
B
Audiology Unit of the ENT Department, Hacettepe University, Ankara, Turkey.
Budak
Gürer G
GG
Oztürk
Göknur Güler
GG
Muluk
Nuray Bayar
NB
Apan
Alpaslan
A
Seyhan
Nesrin
N
D000161:Acoustic Stimulation / Q000379:methods*; D000818:Animals; D003051:Cochlea / Q000503:physiopathology*; D004574:Electromagnetic Fields / Q000009:adverse effects*; D005260:Female; D006198:Hair Cells, Auditory / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D011817:Rabbits; D011897:Random Allocation; D015398:Signal Transduction / Q000502:physiology; D014732:Vibration