Eight groups of 30 male rats each and 8 groups of 10 female rats each were exposed to concentrations of HCC-230fa targeted to 0, 0.50, 2.5, or 25 ppm. Four groups of male and 4 groups of female rats were used for standard toxicological and micronucleus evaluations. The remaining 4 groups of male rats were used for immunotoxicological and sperm asssessment evaluations, and the remaining 4 groups of female rats were used for immunotoxicological evaluation. Animal exposures were whole-body for six hours per day, five days per week for a total of 66 exposures (rats designated for standard toxicological evaluations) or 68 exposures (rats designated for sperm assessment and/or immunotoxicological evaluations) over a 15-week period. Following the exposure period, surviving male rats were kept for a 1- or 3-month recovery period. The analytically determined mean concentrations of HCC-230fa in the exposure chambers targeted to 0.50, 2.5, or 25 ppm were 0.51, 2.5, and 25 ppm, respectively. The daily mean exposure chamber temperatures ranged from 22-27'C. The daily mean relative humidity in the exposure chambers was between 35-70%, and the oxygen concentration was 20-21%. The daily mean chamber airflows ran ed from 290-340 L/min. There were no compound-related mortalities in the study. No compound-related abnormalities were observed during the ophthalmological examination. No clinical signs of toxicity attributed to HCC-230fa were observed during the study. Exposure to HCC-230fa did not significantly alter the sheep red blood cell (SRBC)-specific serum IgM antibody response. Male and female rats exposed to 25 ppm had lower mean body weights, mean body weight gains, and food consumption during the exposure period when compared to controls. Male and female rats exposed to 25 ppm and sacrificed immediately after the exposure period had minimally decreased total leukocyte and lymphocyte counts. These changes were considered to be marginally adverse. There were no leukocytic changes that were considered to be biologically adverse at 2.5 ppm and below.