JACC Report 45 – 1,1-Difluoroethane (HFC-152a)

Abstract

JACC 045 : 1,1-difluoroethane (HFC-152a) (CAS No. 75-37-6) | October 2004

This report has been produced as part of the ECETOC Joint Assessment of Commodity Chemicals (JACC) programme. It presents a critical evaluation of the toxicity and ecotoxicity data on 1,1 difluoroethane (HFC-152a), including results of recent and unpublished toxicological studies conducted under the Programme for Alternative Fluorocarbon Toxicity Testing (PAFT) a. HFC-152a, a colourless, flammable gas, is used as a non-ozone depleting aerosol propellant and an alternative to trichlorofluoromethane (CFC-11) and dichlorodifluoromethane (CFC-12) in foam applications. In the atmosphere, HFC-152a degrades by photo-oxidation over a lifetime of 1.5 years, ultimately yielding carbon monoxide, carbon dioxide and hydrogen fluoride. Its global warming potential is 140 compared to carbon dioxide for an integration time horizon of 100 years. In experimental animals HFC-152a possesses a low order of acute inhalation toxicity, although it can induce cardiac sensitisation at high exposure levels (150,000 ppm, 405,000 mg/m3). HFC-152a was not toxic or carcinogenic in a long-term (2-year) inhalation study in which up to 25,000 ppm (67,500 mg/m3) was administered to rats. HFC-152a did not cause any developmental effects at 50,000 ppm (135,000 mg/m3), the highest level tested. In genetic testing, HFC-152a was not mutagenic in bacteria (Ames assay). HFC-152a caused chromosome aberrations in cultured human lymphocytes, but only after continuous treatment for 19 hours. The response was considered to be of marginal biological relevance. No micronuclei were found in rats exposed (in vivo) to 19,500 ppm (52,700 mg/m3). In the absence of measured data, bioaccumulation and toxicity in aquatic organisms are predicted to be low. aA co-operative programme (1987 – 2000) sponsored by 16 leading chlorofluorocarbon producers [http://www.afeas.org/paft/]