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HYDROFLUOROCARBON-236FA 20 20,000 and 50,000-ppm groups. Although considered exposure related, these changes are not considered to be of toxicological significance. Decreases in total protein and albumin and alterations in blood urea nitrogen (BUN) concentration were also detected but were not dose related. Changes in some serum electrolyte concentrations were not considered to be biologically relevant. Urinalysis revealed no biologically relevant findings. There was no definitive evidence for induction of hepatic peroxisomes in rats following discontinuous subchronic exposure to HFC-236fa at concentrations as high as 50,000 ppm. Reproductive Toxicity There are no reports of reproductive toxicity studies in animals for HFC-236fa. Developmental Toxicity Two developmental toxicity studies (one in rats and one in rabbits) were conducted in animals to examine the developmental effects of HFC-236fa. The highest concentration tested in these studiesâ50,000 ppmâwas the highest that could be attained without supplementing chamber oxygen. Munley (1995) administered HFC-236fa by inhalation to pregnant rats at concentrations of 0, 5,000, 20,000 and 50,000 ppm for 6 hr per day from days 7 to 16 of gestation. The study was terminated on day 22 of gestation. At 20,000 and 50,000 ppm, there were significant dose-related decreases in maternal body- weight gain over the first 2 days of inhalation exposures. At 50,000 ppm, that was accompanied by significant reduction in food consumption and diminished alerting responses during the inhalation exposures. No evidence of maternal toxicity was detected at 5,000 ppm. There was no evidence of developmental toxicity in the fetuses at any exposure concentration tested. Munley (1996) exposed pregnant New Zealand rabbits (20 per group) to HFC-236fa by inhalation at daily (6 hr per day) exposure concentrations of 0, 5,000, 20,000, or 50,000 ppm on days 7 to 19 of gestation. Does were killed on day 29, and fetuses were weighed and examined for external, internal, and skeletal abnormalities. There was no evidence of any maternal or developmental toxicity at any exposure concentration tested. There were no compound-related effects on maternal body weight, weight change,
