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SOLVENT-INDUCED OTOTOXICITY IN RATS: AN ATYPICAL SELECTIVE MID-FREQUENCY HEARING DEFICIT
Citation:
Crofton, K. AND C. Rebert. SOLVENT-INDUCED OTOTOXICITY IN RATS: AN ATYPICAL SELECTIVE MID-FREQUENCY HEARING DEFICIT. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-95/055, 1994.
Description:
Most previous reports of ototoxicity following exposure to a variety of volatile organic solvents have restricted testing to the low- and mid-frequencies of the hearing range in the rat (2-20 kHz). e report here that inhalation exposure to styrene, xylene, toluene and 1,1,2-trichloroethylene resulted in hearing dysfunction only in the mid-frequency range and spared function at lower and higher frequencies. dult male LE rats were exposed via inhalation (whole body) in flow-through chambers. he following exposures were used: styrene, 1600 ppm; 1,1,2-trichloroethylene, 3500 ppm; toluene, 2500 ppm; mixed xylenes, 1800 ppm (n=7-10 per group, 8 hr/day for 5 days), and n-butanol, 4000 ppm (n=10/group, 6hr/day for 5 days). esting of auditory function was conducted 5 to 8 weeks after exposure using reflex modification audiometry (RMA). MA thresholds were determined for frequencies between 0.5 and 40 kHz. esults indicate increased RMA thresholds for the midfrequency tones (e.g., 8 and 16 kHz), but not higher or lower tones, for all solvents except n-butanol. oluene also increased thresholds at 24 kHz. hese data indicate that solvent-induced ototoxicity is restricted to mid-frequencies in rats.