بررسی تأثیر توأم صدا و تولوئن بر عملکرد پاسخ شنیداری ساقه مغز خرگوش در فرکانس‌های خالص 250 تا 2000 هرتز

  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 .