Genotoxicity of Source Water Contaminants 1,3-Dichloropropane, 2,2-Dichloropropane, and 1,1-Dichloropropene in Salmonella, The E.Coli Prophage-Induction Assay and Human Lymphoblastoid Cells

1,3-Dichloropropane(1,3-DCP), 2,2-dichloropropane(2,2-DCP), and 1,1-dichloropropene (1,1-DCPe)are source water contaminants that were placed on the U.S. EPA's Contaminant Candidate List and deemed high-priority for research in 1998. Because there were few toxicologic data available, these chemicals were analyzed for genotoxicity in the Salmonella plate-incorporation assay, the E. coli prophage-induction assay, and in the comet assay using human lymphoblastoid cells. In Salmonella, 1,3-DCP was weakly positive in strains TA1535 and GSTT1. Only 1,1-DCPe produced a dose-response, and only in strain RSJ1OO, the strain containing rat GST5-5. In the prophage-induction assay, 1,3-DCP and 2,2-DCP were weakly positive in the absence of S9, whereas 1,1-DCPe was clearly positive in the absence of S9. Finally, 1,1-DCPe does not induce a positive response in the comet assay. These data indicate that 1,1-DCPe was mutagenic, whereas 1,3-DCP was weakly mutagenic,at the base-substitution allele of Salmonella and generally required GST-theta for activation; 2,2-DCP was not mutagenic. All three compounds were genotoxic in the prophage-induction assay in the absence of S9, and 1,1-DCPe was weakly genotoxic in the presence of S-9. 1,1-DCPe was not clastogenic in human lymphoblastoids. Thus, these compounds are weak mutagens, and further study in human cells will clarify their genotoxic risk to humans.Master of Science in Public Healt