Effects of acute styrene and simultaneous noise exposure on auditory function in the guinea pig.

Although styrene has been demonstrated to disrupt vestibular function acutely, parallel studies have not been conducted in the auditory system. This article presents data on the effects of acute styrene administration by injection and inhalation on cochlear function. No deleterious effect of the maximally tolerated styrene dose on hearing was identified when cochlear function was assessed using a within-subjects design. When guinea pigs were administered styrene by inhalation during a single 7-h period, normal auditory function was observed both 1 and 7 days later as compared to chamber controls which did not receive styrene. In some instances, the interactive effects of noise and simultaneous styrene inhalation were studied to determine whether chemical exposure might enhance the disruptive effects of noise on hearing. While a persistent noise-induced hearing loss was observed 1 day following exposure, subjects administered styrene simultaneously did not show a greater hearing loss than those receiving noise alone. Finally, when a 7-day recovery period for noise-induced hearing loss was interposed before audiometric testing, the combined exposure to styrene and noise was not more potent than noise alone in elevating auditory thresholds. Although auditory dysfunction has been reported following subchronic styrene administration, the current results do not support an ototoxic effect of styrene at the level of the cochlea with short-term exposure.