INACTIVATION OF A TETRACHLOROIMIDE MUTAGEN FROM SIMULATED PROCESSING WATER

The tetrachloroimide chloromethylene)-4,4-dichloro-2,5-pyrrolidinedion e (compound 1), a potent, direct-acting mutagen inducing more than 150 0 revertants/nmol in Salmonella typhimurium strain TA100 (Ames assay) without metabolic activation, is formed during chlorination of simulat ed poultry chiller water. The mutagenicity of this compound decreased rapidly upon exposure to various nucleophilic compounds such as L-cyst eine, N-acetyl-L-cysteine, cysteine ethyl ester, reduced glutathione, sodium sulfite, sodium bisulfite, and L-lysine. The amino acids aspart ic acid and glycine were ineffective under the test condition of pH 7 at room temperature. Loss of mutagenicity was directly related to time of exposure and concentration of nucleophile as measured with N-acety -L-cysteine and L-lysine. The pH of the reaction medium in the range o f 6-8 did not influence the inactivation. Although the reaction produc ts resulting from the exposure of the imide to the nucleophilic compou nds have not been identified, ultraviolet spectral studies and mechani stic considerations suggest that they may result from displacement of a chloride on the imide. The possible significance of these findings t o food safety and to the reduction of the mutagenic potential of poult ry chiller water is discussed.