1,1,1,2-Tetrafluoroethane: repeat exposure inhalation toxicity in the rat, developmental toxicity in the rabbit, and genotoxicity in vitro and in vivo.

Subchronic and chronic studies were carried out in the rat and a developmental toxicity study in the rabbit with exposures to 1,1,1,2-tetrafluoroethane (HFC 134a) by inhalation. In the rat repeated exposure to 50,000 ppm HFC 134a for 13, 52, and 104 weeks elicited no effect on clinical condition, growth, and survival, or on a variety of hematological, clinical chemistry, and urinary parameters. Treatment-related pathological changes were seen only at study termination at 2 years and were confined to increased incidence of Leydig cell hyperplasia and adenoma in male rats exposed to 50,000 ppm. The tumors, which were also seen in control animals, were benign and not life-threatening. A battery of in vitro and in vivo tests gave no evidence of genotoxic activity. With exposure to pregnant rabbits, the only treatment-related effects were of minimal maternal toxicity at high exposure concentrations; there were no effects on fetal development. It is concluded that HFC 134a is of very low toxicity and should be an acceptable alternative to CFCs.