Toxicological profiles of HFC-134a (1,1,1,2-tetrafluoroethane)

Tetrafluoroethane is rapidly absorbed and equilibrated in tissues after inhalation and is eliminated from the blood in expired air with a half life of a few minutes. Metabolism to trifluoroacetic acid occurs only in minor amounts.

Tetrafluoroethane has an extremely low order of acute toxicity. Concentrations over 2,975,000 mg/m3 (700,000 ppm) in the inhaled air are required to produce lethal effects. The symptoms of acute intoxication are characterised by central nervous effects due to narcotic properties seen only at extremely high exposure concentrations.

When tetrafluoroethane is in contact with cutaneous or ocular mucosal membranes it causes slight irritation possibly due to the test procedures. It is not a skin sensitiser.

Tetrafluoroethane can induce cardiac sensitisation in dogs at 340,000 mg/m3 (80,000 ppm) and higher after an exogenous epinephrine challenge.

Tetrafluoroethane showed no adverse effects on fertility in a limited study in mice. It was not teratogenic in rats and rabbits. Only non-specific effects on foetal maturation in the form of delayed foetal ossification in the rat were observed at 212,500 mg/m3 (50,000 ppm) and above.

Tetrafluoroethane was not genotoxic in vitro or in vivo as shown in a large variety of studies including all important end points.

The chronic toxicity of tetrafluoroethane was studied in rats with durations between 2-52 wk at inhalation exposure levels up to 212,500 mg/m3 (50,000 ppm). No toxicologically significant effects were seen in these studies.

Two carcinogenicity studies were conducted. In a limited study in rats with daily oral administration of 300 mg/kg body weight tetrafluoroethane in corn oil over a period of 1 year, and a 16 month post-treatment observation phase, no tumorigenic effect was seen.

In a two year inhalation study with exposures up to 212,500 mg/m3 (50,000 ppm), tetrafluoroethane did not produce neoplastic changes in female rats. In male rats at 212,500 mg/m3 (50,000 ppm) a slight increase in the incidence of testicular Leydig cell hyperplasia and benign Leydig cell adenomas was observed. As tetrafluoroethane is not genotoxic these changes are considered to be non-genotoxic and are not of significance for human hazard at low exposure levels.

There are no reported effects of tetrafluoroethane in man.

Joint Assessment of Commodity Chemicals No. 31
HFC-134a (1,1,1,2-tetrafluoroethane)
ECETOC, February 1995