Isopropanol 13-week vapor inhalation study in rats and mice with neurotoxicity evaluation in rats

This study was conducted to evaluate the possible subchronic toxicity as well as neurobehavioral effects of isopropanol, a widely used industrial and commercial solvent. Five groups, each containing 10 Fischer 344 rats/sex and 10 CD-1 mice/sex, were exposed for 6 hr/day, 5 days/week, for 13 weeks to isopropanol vapor at concentrations of 0 (control), 100, 500, 1500, or 5000 ppm. An additional 15 rats/sex were assigned to the 0, 500, 1500, and 5000 ppm groups for assessment of neurobehavioral function. No exposure-related mortalities occurred during the study. The narcotic effects of isopropanol were noted only during exposures at 1500 and 5000 ppm. These signs, noted during exposures, were typically absent following exposures. The only clinical signs observed following exposures included swollen periocular tissue, perinasal encrustation, and ataxia for rats of the 5000 ppm group. Neurobehavioral evaluations indicated no changes in any of the parameters of the functional observational battery; however, increased motor activity for female rats in the 5000 ppm group was noted at Weeks 9 and 13. Decreases in body weight and body weight gain were observed for rats of the 5000 ppm group at the end of the first week of exposure. During the remaining weeks, increases in body weight and/or body weight gain were observed for rats of the 1500 and 5000 ppm groups. No exposure-related effects on body weight were noted for male mice; however, increased body weight and body weight gain were observed for female mice of the 5000 ppm group.(ABSTRACT TRUNCATED AT 250 WORDS)