Chemical and Toxicological Analysis of Territories Affected by Radiation and Chemical Pollutants: II. Toxicity Effects of Natural Water (in vitro Studies)

The toxic properties of native water samples of surface (river) water and groundwater used to meet drinking water needs in settlements of the Zhizdrinskii and Ul’yanovskii districts of Kaluga Oblast, which were the areas most exposed to radiation after the accident at the Chernobyl nuclear power plant in 1986, are studied. The focus is on manifestations of genotoxic effects, as the most typical effects of radiation pollution of the territory. It is shown that water exhibits, in most of the analyzed samples, a reliable cytogenetic effect in relation to cells of transplanted cultures of the Chinese hamster (CHO and 237 clones). At the same time, the extractable ether-soluble organic substances contained in the analyzed water samples exhibit genotoxic activity only after they are concentrated by a factor of 100. In parallel, the mutagenic toxicity of water samples was analyzed using the Ames test. Without metabolic activation (in the absence of additions of the S9 fraction of the rat liver), most water samples from the drinking water supply sources show an acute toxicity to Salmonella strains (TA 97, TA 98, and TA 100). The results of biological tests are discussed in relation to previously obtained data on the radiation effects of the Chernobyl accident on the aquatic environment of the Dnieper reservoirs. It is concluded that the principal role in the manifestation of genotoxic properties may be played by radioactive isotopes that are hidden from traditional methods of radiation monitoring and are sources of alpha and beta radiation that lead to the formation of metal ions in the superoxidized state in the presence of environmental pollution by transition metals, in particular, to the formation of microcolloidal particles of mixed-valence manganese Mn(III, IV) that serve as carriers for the OH radical. The acute and chronic toxicity of the analyzed river and groundwater samples is established by bioassay methods using test organisms of various trophic levels (bacteria, ciliates, and Daphnia). No correlation with toxicity is detected in any of the traditionally monitored hydrochemical indices of water quality.