Activity of bromochlorodifluoromethane (BCF) in three mutation tests

The halocarbon BCF was tested in 3 assays to assess its mutagenicity and clastogenicity. It produced a positive response in Salmonella typhimurium strain TA1535 but was negative in TA1537, TA1538, TA98 and TA100. In an L5178Y mouse lymphoma microwell assay (TK locus), BCF was negative. BCF was administered at 5000 and 50 000 ppm in air for 6 h to groups of C57B1/6J mice of both sexes. Animals were killed at 24, 48 and 72 h after cessation of exposure and the incidence of bone marrow micronuclei per 1000 PCEs determined. There was no significant difference in the incidences of micronuclei between untreated animals and those exposed to either concentration of BCF at any of the sampling times. These results suggest that BCF is mutagenic in vitro in only one strain of Salmonella; in mammalian cells the compound induced no gene mutation in vitro nor clastogenic activity in vivo at doses that also produced clear evidence of toxicity.