In an inhalation toxicokinetic study, rats were exposed to 1,000, 5,000 and 50,000 ppm (4,900, 24,500 and 245,000 mg/m3) HFC-125 for 6 hours in individual inhalation chambers. Results indicated a slight uptake at the end of the exposure period. Due to the low absorption of HFC-125, kinetic constants of uptake and metabolism were not calculated. In limited metabolic studies in vivo in the rat, the metabolism of pentafluoroethane was negligible.
The acute inhalation toxicity of pentafluoroethane is very low. The 4-hour LC50 in the rat is greater than 3,928,000 mg/m3 (800,000 ppm). During the exposure the only clinical signs were ataxia, decrease of locomotor activity and dyspnea.
As with many other fluorocarbons, inhalation of high concentration of pentafluoroethane, followed by an intravenous epinephrine challenge to simulate stress, can induce a cardiac sensitisation response in dogs. The threshold concentration for this effect was 491,000 mg/m3 (100,000 ppm)and the No Observed Effect Concentration (NOEC) was 368,250 mg/m3 (75,000 ppm).
Exposure by inhalation up to 245,000 mg/m3 (50,000 ppm) 5 days a week for 4 to 13 consecutive weeks, did not induce any toxic effect and the NOEC was greater than 245,000 mg/m3 (50,000ppm). Developmental toxicity studies by inhalation route were carried out in both rats and rabbits. No evidence of embryotoxicity or teratogenicity was seen even at exposure levels as high as 245,000mg/m3 (50,000 ppm).
Pentafluoroethane was not mutagenic both in vitro and in vivo studies using bacteria, mammalian cell lines and in the mouse micronucleus assay.
There are no reported effects of pentafluoroethane in man.
An occupational exposure limit (8-hour time weighted average) of 1,000 ppm (4,910 mg/m3) is recommended by producers.
Joint Assessment of Commodity Chemicals No. 24
HFC 125 (Pentafluoroethane)
ECETOC May 1994
OECD SIDS Dossier on pentafluoroethane (354-33-6)