HFA-134A (1,1,1,2-TETRAFLUOROETHANE) - LACK OF ONCOGENICITY IN RODENTS AFTER INHALATION

1 Groups of 60 male and 60 female B6C3F1 mice or Hanlbm Wistar rats were exposed to HFA-134a using snout-only inhalation exposure techniques for periods of one hour daily for at least 104 weeks. HFA-134a was delivered directly from cylinders at vapour concentrations of 2500, 15 000 and 75 000 ppm for mice and from metered-dose inhalers at vapour concentrations of 2500, 10 000 and 50 000 ppm for rats. 2 Intended dosages were achieved. 3 Evidence of absorption was found at each dose level and was dose related. 4 Neither species suffered any treatment related effects on survival, clinical signs, body weights, haematology nor on the type, incidence, site or severity of gross lesions. 5 There was no effect of treatment on the type, incidence, site or severity of neoplasms in mice or rats. 6 There were no non-neoplastic findings related to treatment in mice. 7 HFA-134a was considered not to be oncogenic and to provide a safe alternative to chlorofluorocarbons for use in pharmaceutical metered-dose inhalers.