Neurotoxicity evaluation of rats after subchronic inhalation exposure to isobutanol

The subchronic neurotoxic effects of isobutanol were studied by exposing Sp rague-Dawley rats to isobutanol vapor concentrations of 0, 250, 1000, and 2 500 ppm for 6 hrs/day, 5 days/wk, for 3 months. A comprehensive set of neur otoxicity tests (functional observational battery, motor activity, perfusio n fixation neuropathology, and schedule-controlled operant behavior) includ ing an assessment of complex behavior dependent on learning and memory was conducted. In addition, full histopathology and blood chemistry evaluations were conducted in order to assess any potential functional/behavioral effe cts in the context of other possible systemic toxicities. There were no mor phological or behavioral effects indicative of a specific, persistent or pr ogressive effect of isobutanol on the nervous system at exposure concentrat ions up to 2500 ppm. A slight decrease in response to external stimuli was observed during exposures at all concentrations. These effects are likely t ransient effects of acute exposure to isobutanol. (C) 1999 Intox Press, Inc .