Mutagenicity of dichloroacetylene and its degradation products trichloroacetyl chloride, trichloroacryloyl chloride and hexachlorobutadiene.

Dichloroacetylene (DCA) is a highly reactive compound that decomposes rapidly in contact with air into a series of chlorinated aliphatic hydrocarbons (e.g., phosgene, trichloroacetyl chloride, trichloroacryloyl chloride and hexachlorobutadiene). Experiments were performed to compare the mutagenic properties of DCA and its degradation products on the histidine-dependent tester strains TA98 and TA100 of Salmonella typhimurium. In these experiments, DCA vapour was streamed under analytical control through the bacterial suspensions. DCA is soluble in aqueous solution and was stable under the experimental steady-state conditions of the bacterial exposure. There is a linear correlation between the supply of DCA vapour and solubilized DCA in the range of 1000 and 16 000 ppm. Mutagenic response was observed with strain TA100 if the bacteria were suspended in Oxoid medium. No mutagenicity could be detected with strain TA98. DCA mixtures with acetylene, as used as stabilizer for animal experiments, were not mutagenic in either bacterial strain, irrespective of the presence or absence of S9 mix in the cell suspension. One of the degradation products of DCA, trichloroacryloyl chloride, showed pronounced mutagenic properties with and without drug-metabolizing enzymes. Other degradation products of DCA, such as trichloroacetyl chloride and hexachlorobutadiene, were not mutagenic, either in the presence or absence of liver homogenate.