SAFETY ASSESSMENT OF HCFC-141B - USE AS A BLOWING AGENT FOR INSULATION IN BUILDING CONSTRUCTION AND REFRIGERATION

We have performed a risk assessment to evaluate potential risk to huma n health that might be associated with the use of HCFC-141b (1,1-dichl oro-1-fluoroethane) in rigid foam insulation boards for home sheathing and in foam insulation for refrigerators. Risks presented by the blow ing agent itself and its potential contaminants and breakdown products (HCFC-151a, HCFC-1131a, and vinylidene chloride) were evaluated follo wing the standard procedures outlined by the National Academy of Scien ces. HCFC-141b showed an equivocal tumorigenic effect in rats (an incr ease in benign testicular tumors that was not dose related), while vin ylidene chloride was associated with an increase in tumor incidence (k idney tumors in mice) in a single study out of 19 in which its carcino genicity has been investigated. The other two contaminants have not be en tested for carcinogenicity, but do show some evidence of genotoxici ty in short-term tests. However, even if all of these substances are t reated as potential carcinogens, under the anticipated conditions of h uman exposure the maximum theoretical risk to a resident is less than one in one million (10(-6)). Also, no other toxic effects would be ant icipated. (C) 1994 Academic Press, Inc.