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Toluene-induced ototoxicity by subcutaneous administration.
Neurobehavioral Toxicology and Teratology
|January 1, 1986
Summary
Toluene exposure causes hearing loss in rats, even without inhalation. This study shows direct injection of toluene leads to irreversible hearing damage, indicating noise from inhalation systems is not the primary cause.
Area of Science:
- Toxicology
- Neuroscience
- Auditory Science
Background:
- Inhalation of toluene is known to cause irreversible hearing loss in rats.
- The role of noise from inhalation systems as a contributing factor to toluene-induced hearing loss is unclear.
Purpose of the Study:
- To investigate if noise from inhalation systems is a major factor in toluene-induced hearing loss.
- To determine if non-inhalation toluene exposure causes similar auditory effects.
Main Methods:
- Weanling male Fischer-344 rats were subcutaneously injected with toluene (1.5 or 1.7 g/kg) or PEG-300 (control) twice daily for 7 days in a quiet environment.
- Auditory response thresholds were estimated using a conditioned avoidance response (CAR) task, generating tone intensity-response functions at 4, 8, 12, and 20 kHz.
- Performance on a multisensory CAR task involving light and footshock was also assessed.
Main Results:
- Toluene exposure resulted in a dose-related hearing loss at frequencies of 8 kHz and above.
- No hearing loss was observed at 4 kHz.
- Toluene did not affect the performance of the CAR task in response to light, nonaversive footshock, or a 4-kHz tone.
Conclusions:
- Noise from inhalation systems is not a major factor in toluene-induced hearing loss.
- Direct penetration of toluene vapors is not necessary for inducing hearing loss.
- Toluene-induced hearing loss is frequency-specific and occurs via non-inhalation routes.