Mid-frequency hearing loss in rats following inhalation exposure to trichloroethylene: evidence from reflex modification audiometry.
The present experiments were undertaken to characterize the hearing loss associated with 1,1,2-trichloroethylene (TCE) exposure. Adult male Long-Evans (LE) rats were exposed to TCE via inhalation (whole body) for 6 h/day for 5 days. The concentration-effect function (0-4000 ppm) was determined 3 weeks post-exposure. Animals were tested for auditory thresholds to 4, 8, 16, 24, 32, and 40-kHz tones using reflex modification audiometry. In a separate experiment, the time course of effects was determined by monitoring 16-kHz thresholds prior to, 1 h following each of the 5 exposure days, and 5 days, 1, 2, 4, 8, and 12 weeks post-exposure. At 14 weeks, these same animals were tested for thresholds to 0.5, 1, 2, 4, 8, 16, 24, 32, and 40-kHz tones. Results indicate elevated thresholds (hearing loss) for the 4000 ppm group at 8 and 16 kHz of approximately 18 and 30 dB, respectively. Time-course data demonstrated a rapid onset, a 20-dB loss at 16 kHz after the fifth exposure day, and a 40-dB loss by 2 weeks that persisted up to 14 weeks post-exposure. These data demonstrate an atypical and persistent, mid-frequency hearing loss in rats following inhalation exposure to TCE.
Crofton
K M
KM
Neurotoxicology Division, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711.
Zhao
X
X
D000280:Administration, Inhalation; D000818:Animals; D001299:Audiometry; D001309:Auditory Threshold / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006312:Hearing Loss, Bilateral / Q000139:chemically induced*; D006316:Hearing Loss, High-Frequency / Q000139:chemically induced; D008297:Male; D051381:Rats; D012022:Reflex, Acoustic / Q000187:drug effects*; D013997:Time Factors; D014241:Trichloroethylene / Q000008:administration & dosage / Q000633:toxicity*
D014241:Trichloroethylene