Lack of mutagenicity of two possible metabolites of halothane.

1,1-Difluoro-2-bromo-2-chloroethylene, a probable metabolite of halothane, was purified by preparative gas chromatography and tested for mutagenicity in the Salmonella/mammalian liver system developed by Ames and colleagues. 1,1,1-Trifluoro-2-chloroethane which had been isolated from the breath or rabbits anesthetized with halothane was also tested for mutagenicity in a similar manner. Both compounds were found to be nonmutagenic in this bacterial system. Although neither this study nor any other has yet been able to demonstrate that halothane or any of its metabolites is genetically active, nevertheless, unnecessary occupational exposure to the drug should be avoided due to the possibility that future studies could reveal adverse effects secondary to halothane.