بررسي تاثير توام صدا و تولوئن بر عملكرد پاسخ شنيداري ساقه مغز خرگوش در فركانس هاي خالص 250 تا 2000 هرتز

(Frequencies 250-2000 Hz) per Auditory Brain Stem Response (ABR) on Rabbit

Introduction: In the present study, was performed to investigate the relationship between toluene(1000 ppm), noise, toluene and toluene along with noise (frequencies 250- 2000 Hz) per auditory Brain Stem response (ABR) on rabbits in which being exposed to this contaminants. Materials & Methods: Three months old, male adult white New Zealand rabbits (1400-1700 g body weight) were used throughout this study. The groups were divided according to type of exposure summarized as follows: group 1, controls (unexposed); group 2, exposed to toluene(1000 ppm); group 3, noise exposure (100 dB SPL, 250HZ, 8 h/day, 5days/week), 100 dB SPL; group 4, toluene (1000 ppm) and noise exposure (250HZ, 8 h/day, 5days/week), group 5, noise exposure (500Hz); group 6 toluene and noise exposure (500HZ), group 7, noise exposure (1000Hz); group 8, toluene and noise exposure (1000HZ); group 9, noise exposure (2000Hz); group 10, toluene and noise exposure (2000HZ). Sound pressure level in the chamber was measured using a Bruel and Kjaer 2231 sound level meter (Denmark) and toluene concentration was measured with gas chromatograph. Rabbits based on their hearing ability were measured by Auditory Brainstem Response (ABR). Results: A low and mid frequencies (250,500 and 1000Hz) auditory impairment was observed following exposure to toluene alone and noise alone. Toluene followed by noise resulted in a higher threshold at all frequencies. The latencies of V wave (5th wave) increased after treatments. Conclusion: Exposure of rabbits to only toluene made hearing impairment whereas toluene and noise exposure (100 dB SPL, 250 Hz - 2000Hz, 8 h/day, 5days/week) were worse than hearing impairment.