MUTAGENICITY IN-VITRO OF 3,4-DICHLORO-5-HYDROXY-2(5H)-FURANONE (MUCOCHLORIC ACID), A CHLORINE DISINFECTION BY-PRODUCT IN DRINKING-WATER

The mutagenicity of chlorinated humic drinking waters is accounted for mainly by a single contaminant, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), as assessed in Solmonella typhimurium strain TA100. In the present study, 3,4-dichloro-5-hydroxy-2(5H)-furanone (mucochloric acid, MA), another drinking water contaminant much less potent os a mutagen in TA100 than MX, was tested in Chinese hamster ovary (CHO) cells for the induction of mutation at the hypoxanthine phosphoribosyl transferase (hprt) locus to 6-thioguanine resistance (TG(r)). Unexpectedly, MA induced TG(r) mutants in CHO cells with a potency comparable to that reported previously for MX. In subsequent experiments with S. typhimurium, the presence of pKM101 plasmid in strain TATOO increased susceptibility to the mutagenicity of MA, but much less than to that of MX, relative to the parental strain TA1535 lacking pKM101. The difference between the two compounds in TA100 thus appears to be due to a higher enhancement of the mutagenicity of MX than that of MA by pKM 101 mediated error-prone DNA repair. (C) 1995 Wiley-Liss, Inc.