Mutagenicity of 2- and 3-carbon halogenated compounds in the Salmonella/mammalian-microsome test

Short-chain, 2- and 3- carbon halogenated hydrocarbons were tested for mutagenicity for Salmonella typhimurium strain TA 100 both with and without the presence of S-9. Without exception, all brominated derivatives were more mutagenic than the chlorinated derivatives, usually by a substantial order of magnitude. 2-Fluoroethanol, the only fluorinated compound tested, showed little or no mutagenic activity up to 100 micromole per plate concentration. Two highly purified propane derivatives containing a halogen atom on each of the three carbons showed little or no direct mutagenic activity. A third trihalogenated compound with a halogen atom on each carbon atom showed some direct mutagenic activity, probably due to impurities. However, all three trihalogenated compounds were highly active mutagens following S-9 activation. The presence of a double bond in the case of 1, 2, 3-trichloropropene resulted in a higher level of direct mutagenic activity than 1, 2, 3-trichloropropane, but activation with S-9 resulted in a further increase in mutagenic activity with the former compound. On the other hand, S-9 caused a substantial decrease in mutagenic activity of most compounds containing a double bond. With the presence of an alcoholic group in a compound, the addition of S-9 caused variable responses, increasing the number of his+ revertant colonies due to 2, 3-dibromopropanol but had little or no effect with five other compounds containing an alcoholic group. Evidence is also presented that the position of a double bond in relation to the halogen atoms may influence mutagenic activity.