The mutation spectra of chlorinated drinking water samples using the base-specific TA7000 strains of Salmonella in the microsuspension assay

A protocol for the evaluation of genotoxicity in bile of carp (Cyprinus carpio) exposed to lake water treated with different disinfectants

A sensitive and rapid method to evaluate toxic and genotoxic properties of drinking water supplied from Lake Trasimeno (Umbria, Central Italy) was worked out analysing bile in Cyprinus carpio exposed for 20 d to lake water treated with 3 different disinfectants, sodium hypochlorite (NaClO), chlorine dioxide (ClO(2)) and peracetic acid (PAA). Fish were sacrificed at 0, 10 and 20 d in order to investigate the time course of these endpoints. An aliquot of bile samples was fractionated by adsorption on C(18) silica cartridges and the genotoxic potential of whole bile and of bile fractions was evaluated by the single-cell microgel-electrophoresis (comet) assay on human colonic adenocarcinoma cells (Caco-2). Bile (both whole and fractionated) from specimens exposed to the three disinfectants always showed a genotoxic activity as compared to the control group. The results of this study provide evidence that all three disinfectants cause an increase in bile genotoxicity of chronically exposed fish.

Integrated disinfection by-products research: salmonella mutagenicity of water concentrates disinfected by chlorination and ozonation/postchlorination

Although chemical disinfection of drinking water is a highly protective public health practice, the disinfection process is known to produce toxic contaminants. Epidemiological studies associate chlorinated drinking water with quantitatively increased risks of rectal, kidney, and bladder cancer. One study found a significant exposure-response association between water mutagenicity and relative risk for bladder and kidney cancer. A number of studies found that several types of disinfection processes increase the level of mutagens detected by the Salmonella assay. As part of a comprehensive study to examine chlorinated and ozonated/postchlorinated drinking water for toxicological contaminants, the Salmonella mutagenicity assay was used to screen both volatile and nonvolatile organic components. The assay also compared the use of reverse osmosis and XAD resin procedures for concentrating the nonvolatile components. Companion papers provide the results from other toxicological assays and chemical analysis of the drinking water samples. The volatile components of the ozonated/postchlorinated and chlorinated water samples and a trihalomethane mixture were mutagenic to a Salmonella tester strain transfected with a rat theta-class glutathione S-transferase and predominantly nonmutagenic in the control strain. In this study, the nonvolatile XAD concentrate of the untreated water possessed a low level of mutagenic activity. However, compared to the levels of mutagenicity in the finished water XAD concentrates, the contribution from the settled source water was minimal. The mutagenicity seen in the reverse osmosis concentrates was < 50% of that seen in the XAD concentrates. Overall, mutagenic responses were similar to those observed in other North American studies and provide evidence that the pilot plant produced disinfection by-products similar to that seen in other studies.