The acute and subchronic toxicity of 1,1-dichloro-1-fluoroethane (HCFC
-141b), a CFC alternative, was evaluated in several acute and subchron
ic studies to assist in establishing proper handling guides. Data from
acute toxicity studies in rats and rabbits demonstrated that HCFC-141
b has very low acute toxicity. HCFC-141b was not a skin irritant, but
was a mild eye irritant, in rabbits and was not a skin sensitizer in g
uinea pigs. Skin application of HCFC-141b to rabbits at 2000 mg/kg bod
y weight produced no adverse effects. Oral administration at 5000 mg/k
g body weight did not cause any deaths or clinical signs of toxicity i
n rats. The 4-hr LC(50) for HCFC-141b was about 62,000 ppm in rats. Re
peated exposures of rats for 6 hr/day, 5 days/wk for up to 90 days at
concentrations of 2000, 8000 or 20,000 ppm did not result in significa
nt adverse effects. Minor, but dose-dependent, reductions in body weig
ht were observed in male and female rats during the 90-day study. Decr
eased responsiveness was also observed in rats but only at 20,000 ppm.
An increase in serum cholesterol or triglycerides was observed in mal
e and female rats at 20,000 ppm, and in males at 8000 ppm. No specific
organ pathology was noted in these subchronic inhalation studies. The
no-observable-adverse-effect level (NOAEL) from these studies was 800
0 ppm. Results from other studies demonstrate that HCFC-141b was not n
eurotoxic in rats. As with trichlorofluoroethane (CFC-11), a cardiac s
ensitization response to an intravenous epinephrine challenge occurred
in dogs with HCFC-141b at 5000 ppm and higher concentrations in exper
imental screening studies.