Toxicological profiles of HFC-143a (1,1,1-trifluoroethane)

1,1,1-Trifluoroethane (HFC-143a) is a colourless, flammable gas that is mainly used as a blend component for air conditioning and refrigeration systems.

When released into the environment, HFC-143a is expected to volatilise almost entirely into the atmosphere, where it will be slowly degraded via trifluoroacetaldehyde to HF and CO2 as final products. HFC-143a does not deplete the stratospheric ozone layer, but its global warming potential (3,800 relative to CO2) is comparable to 4,000 for trichlorofluoromethane (CFC-11).

HFC-143a has not been tested in aquatic organisms. Its environmental toxicity is assumed to be negligible because it volatilises to air.

Following inhalation, HFC-143a is poorly absorbed and rapidly excreted in both laboratory animals and humans. Trifluoroethanol is the principal metabolite in rats.

HFC-143a has a low acute toxicity in rats following inhalation. Cardiac sensitisation to adrenaline was induced in dogs when the HFC-143a was inhaled at a level of 300,000 ppm. Following a 4-week exposure study, there were effects on the testicles of male rats in one study, but two other repeat-exposure studies, one 4 weeks and the other 13 weeks at the same exposure levels, were without any toxic effect. This effect was attributable to confounding factors related to the method of exposure.

In vitro, the genotoxic potential of HFC-143a is low: the majority of the tests were negative. There was no genotoxicity in a micronucleus test in vivo.

Following oral ingestion of HFC-143a for one year, no tumours were observed in rats. Possible reproductive effects of HFC-143a have not been studied specifically. There was no developmental toxicity seen in studies in rats and rabbits.

Human volunteers showed no adverse effect when exposed for 2 hours to 500 ppm HFC-143a.

In the USA, an occupational exposure limit (8-hour time-weighted average) of 1,000 ppm is recommended by the American Industrial Hygiene Association.

Joint Assessment of Commodity Chemicals No. 52 Trifluoroethane
ECETOC, October 2006