Lack of trigeminal nerve toxicity in rats exposed to trichloroethylene vapor for 13 weeks.
Male and female Fischer-344 rats were exposed to 1,1,2-trichloroethylene (TCE) at 250, 800, or 2500 ppm for 6 h/day, 5 days/week, for 13 weeks. Weekly body weights and daily clinical observations were recorded and a functional observational battery (FOB) was performed monthly. Postexposure neurotoxicological evaluations included an electrodiagnostic evaluation of auditory function, the trigeminal nerve, and a comprehensive neuropathological examination. After 8 weeks of exposure, female, but not male, rats exposed to 2500 ppm were slightly more reactive to handling than the controls but not after 13 weeks of exposure. After 13 weeks, female rats exposed to 2500 ppm TCE were slightly more active during the 1-min observation period than the controls. There were no treatment-related differences in grip performance, landing foot splay, or on the trigeminal nerve-evoked potential at any dose. At 2500 ppm TCE, mild frequency-specific hearing deficits were observed, including elevated tone-pip auditory brainstem response thresholds. Focal loss of hair cells in the upper basal turn of the cochlea was observed in 2500 ppm-exposed rats. Except for the cochleas of 2500 ppm-exposed rats, no treatment-related lesions were noted during the neuro-histopathologic examination. The no-observable-adverse-effect level for this study was 800 ppm based on ototoxicity at 2500 ppm.
Albee
Ralph R
RR
Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, Michigan 48674, USA. RAlbee@dow.com
Spencer
Pamela J
PJ
Johnson
Keith A
KA
Bradley
Greg J
GJ
Marable
Brian R
BR
Wilmer
Jan W
JW
Mattsson
Joel L
JL
D000280:Administration, Inhalation; D000818:Animals; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects*; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects; D005260:Female; D008297:Male; D019055:No-Observed-Adverse-Effect Level; D009925:Organ of Corti / Q000187:drug effects / Q000473:pathology; D051381:Rats; D011916:Rats, Inbred F344; D012997:Solvents / Q000633:toxicity*; D014241:Trichloroethylene / Q000633:toxicity*; D014276:Trigeminal Nerve / Q000187:drug effects* / Q000502:physiology
D012997:Solvents; D014241:Trichloroethylene