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Sensory System Alterations Following Occupational Exposure to Chemicals
Published in Lucio G. Costa, Luigi Manzo, Occupatinal Neurotoxicology, 2020
Electrophysiological studies following the acute and subchronic effects of trichloroethylene on the rabbit and rat visual systems have revealed equivocal results.64-66 The b-wave, but not the a-wave, of four light-adapted rabbits acutely injected with trichloroethylene was decreased for at least four hours post-injection.66 Rabbits subchronically exposed (via inhalation) to low and high levels of trichloroethylene exhibited decreases and increases, respectively, in the amplitude of selected waveforms of the light-adapted visual evoked potential.65 Six weeks following exposure, some recovery was evident. In contrast, rats exposed (via inhalation) to much higher levels of trichloroethylene exhibited no changes in the light-adapted visual evoked potential or somatosensory evoked potential, but instead exhibited a high-frequency hearing loss as assessed by the brainstem auditory evoked potential.66
Hearing loss, lead (Pb) exposure, and noise: a sound approach to ototoxicity exploration
Published in Journal of Toxicology and Environmental Health, Part B, 2018
Krystin Carlson, Richard L. Neitzel
The 24 included human studies used a range of hearing tests, including DPOAEs, pure-tone audiometry, and brainstem auditory evoked response (BAER), each of which measures different aspects of the hearing system. DPOAEs, used in two human studies, are best used to assess cochlear outer hair cell function. Audiometry, used in 15 studies summarized for this review, identifies the lowest level of subjectively detectable sound. Finally, BAER, also called brainstem auditory evoked potentials (BAEP), used in 11 studies, measures neuronal transmission of action potentials to the auditory center of the brain. As Pb is a known neurotoxicant, further exploration into modification of auditory neural processing through BAER is likely worth investigation in Pb ototoxicity studies. Past studies have found that correlations between pure-tone audiometry and DPOAEs may be poor (Engdahl, Tambs, and Hoffman 2013). Determining the best auditory function measures for epidemiological analysis will require a more complete understanding of mechanisms surrounding Pb ototoxicity.