Mutagenicity of coal tar paints used in drinking water distribution systems

The aim of this study was to evaluate the mutagenicity of coal tar paints used for coating drinking water tanks and pipes, as a preliminary screening for potential genotoxic hazards associated with leaching of mutagens into drinking water during water storage and distribution. To this end, the Salmonella/microsome assay was performed on different fractions of two paints. The fractions were obtained using different fractionation procedures (a sequential solvent extraction and an acid-base fractionation) for removing the presence of inhibitory components. Both fractionation procedures confirmed an extraordinarily high mutagenicity in both paints, with metabolic activation, much higher than the mutagenicity of the unfractionated paints. The acid-base fractionation was more time-consuming but gave higher mutagenicity recoveries and provided information as to the general nature of the genotoxic constituents, which were concentrated in the neutral fractions. On the other hand, the sequential solvent extraction by sonication was a shorter and simpler method and permitted to reveal the presence of direct-acting mutagens. It is concluded that the application of the Salmonella/microsome assay coupled with both fractionation methods may give complementary and confirmatory data on the genotoxic properties of these coal based paints, as a screening of the potential mutagenic/carcinogenic hazards derived from these materials used in drinking water distribution systems.