Umu test for detecting the SOS-inducing activity (genotoxicity) using Salmonella typhimurium TA1535/pSK1002 has been applied for studies of genotoxicity of chlorine-treated amino acids. Five amino acids tested (glycine, lysine, methionine, proline, serine) showed the SOS-inducing activity after the chlorine treatment. The SOS-inducing activity of the chlorine-treated amino acid solution was relatively stable at freezing condition, though the activity decreased rapidly at room temperature. Formation of the SOS-inducing substancs were effected to the concentration of amino acids in the reaction mixture. The suitable concentration of amino acids for formation of SOS-inducing substaces was different from each amino acids.
SOS-inducing activity of some halogenated organic chemicals such as halo alcohol and halo acetonitrile which were detected in the amino acids and chlorine reaction mixture were observed. However, 11 wellknown halogenated chemicals (mono-, di-, tri- chloroacetic acid, mono-, di-, tri- chloroacetonitrile, mono-, di- chloroacetone, 2,2'-dichloro-ethyl ether, chloral hydrate, nitromethane) did not show SOS-induction.
Present studies indicate that harmless amino acids could be converted into genotoxic substances by chlorine treatment. To clarify the structure and formation mechanisms of genotoxic products, more detailed studies are concidered to be necessory.