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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
Occupational medicine - interface with toxicology
Published in Chris Winder, Neill Stacey, Occupational Toxicology, 2004
There are very few specific tests. The usual laboratory investigations fall into the following categories: tests for increased levels of solvents (e.g. in expired air or for slowly metabolised solvents, in the urine)tests for increased levels of metabolites excreted (e.g. in the urine, phenol levels after benzene exposure, trichloroacetic acid and similar compounds after trichlorethylene exposure, hippuric acid after toluene exposure, and methylhippuric acid after xylene exposure)tests for functions of target organs: central nervous system (electroencephalography, psychomotor tests of memory and reaction times, etc.); peripheral nervous system (nerve conduction velocity, electromyography, and use of visual and somatosensory evoked potential).
Evaluation of potential health effects associated with occupational and environmental exposure to styrene – an update
Published in Journal of Toxicology and Environmental Health, Part B, 2019
M.I. Banton, J.S. Bus, J.J. Collins, E. Delzell, H.-P. Gelbke, J.E. Kester, M.M. Moore, R. Waites, S.S. Sarang
The longest-term styrene inhalation study in which ototoxicity was examined is an unpublished subchronic study (Albee et al. 1992) described in the European Union Risk Assessment Report for Styrene (U.K. HSE, 2008). Groups of 14 male Fischer-344 rats were exposed to 50, 200, or 800 ppm styrene for 6 h/day, 5 days/week, for 13 weeks. After 13 weeks, evoked potential tests were performed on 12 rats per group. There were no exposure-related effects on body weight or mortality. Histopathological changes in the organ of Corti were observed in rats exposed to 800 ppm styrene and included loss of two outer hair cells per cross section from the upper basal turn and the occasional absence of an outer hair cell from the lower middle turn. No alterations were detected in the inner hair cells, the Deiters’ cells, and the pilar cells. No treatment-related alterations in somatosensory evoked potential from the sensory cortex or the cerebellum were observed; however, the 800-ppm group exhibited elevations in auditory brainstem response (ABR), specifically increases of approximately 40 dB at 16, 25, and 30 kHz. Therefore, the hair cell loss at 800 ppm occurred in the cochlea in areas that relate to mid-high frequency (15, 30 kHz) hearing. At the two lower styrene exposure concentrations, neither histopathological effects in the organ of Corti nor effects on ABR thresholds were observed. Thus, the NOAEC for ototoxicity in this study was 200 ppm.