Mutagenicity of the combination of a volatile anaesthetic and nitrous oxide

The mutagenic potential of halothane, enflurane and isoflurane in combination with nitrous oxide was investigated using the sex-linked recessive lethal assay in the fruit fly Drosophila melanogaster. Male wild-type flies were exposed for 1 h to 1 or 2% volatile anaesthetic with various concentrations of nitrous oxide up to 75%. They were then mated with untreated females of the Basc marker strain. A brooding pattern was used to assess mutagenicity at different germ cell stages. The rate of lethal mutations was assessed in the F2 generation. Halothane produced a dose-dependent increase in the rate of lethal mutations, but the mutagenicity was independent of the presence of nitrous oxide and of the stage of germ cell formation. Neither enflurane nor isoflurane was mutagenic in the presence of nitrous oxide.