Background. Natural aquatic ecosystems are the habitat of many organisms, a source of drinking water, a resource for human activities and are subjected to anthropogenic pressure. In this regard, interest in studying the genotoxicity and mutagenicity of surface waters has increased significantly. The aim of this study is to investigate the cytotoxic, genotoxic and mutagenic effects of the surface waters of the suburban area of Almaty. Material and methods. The research materials were water samples of the rivers Esik, Turgen and Lake Esik. The atomic absorption method, lux-test, cytogenetic tests (Hordeum vulgare L.), phytotoxicity test (Allium cepa L.) and embryotoxicity (Danio rerio H.) were used. Results. Physico-chemical water analysis revealed an excess of MPC for Mn, Pb, Cd, Zn. Using the lux-test on E. coli KatG strains, the pro-oxidant activity of Esik R. water. On the plant test objects revealed toxicity and mutagenicity of water samples. The results of bio-testing of natural waters with D. rerio revealed their high toxicity and teratogenicity for embryos at all stages of development. Conclusion. The results of this study obtained on various test-systems and test-objects indicate that surface waters are contaminated by environmentally dangerous factors that pose a threat to biota and human health.

Ecological monitoring, including water resources, is included in a set of measures for the rational use and protection of the environment. Currently, the assessment of water resources' genotoxicity and mutagenicity is an essential component of ecological monitoring.This research aimed to investigate water's genotoxicity from the Esentai and Ulken Almaty rivers flowing in Almaty. It was established that the content of Fe, Cu, Co, Ni, Pb, and Cd in the Almaty rivers water does not exceed the maximum permissible concentration (MPC). In contrast, zinc content in the Esentai and Ulken Almaty rivers' water exceeded the MPC, respectively, by 1.1 and 7.7-folds, manganese – 2.1, and 1.9-folds. It was found that water samples from the Esentai and Ulken Almaty rivers showed a DNA-damaging effect on the studied cells (bone marrow, liver, kidneys, and spleen) of laboratory mice. In the cells of the studied organs in the experimental groups, the frequency of single-strand DNA breaks a statistically significant increase compared to the control group's animal. The genotoxic action's organospecificity of the studied river waters on laboratory mice was established. According to their sensitivity to water's genotoxic effect, experimental mice's organs can arrange in the following order: spleen and bone marrow> liver> kidneys. An increase in lipid peroxidation products was found in the laboratory mice' liver that drank water from the Esentai and Ulken Almaty rivers. Thus, the results of the physicochemical, molecular-genetic, and biochemical analysis of water on animal test objects indicate the presence in the investigated natural surface waters of chemicals with genotoxic and toxic activity. Keywords:surface waters; heavy metals; DNA comet assay, organ specificity, lipid peroxidation

N-Nitrosodimethylamine (NDMA) was shown to have genotoxic properties in acute and subacute studies on laboratory mice. The organ-specificity of the genotoxic effect of NDMA was revealed using the Comet assay. The most sensitive organs to the action of NDMA were kidneys and liver. DNA damage in liver cells of NDMA-treated animals at doses of 4.0 and 8.0 mg/kg, increased compared to control in 6.9 and 12.5 (р < 0.001), and in kidney cells – in 8.1 and 14.2 times (р < 0.001), respectively. NDMA also showed genotoxic activity in the reproductive cells of experimental animals, causing structural disorders of synaptonemal complexes in spermatocyte. In NDMA-treated animals at a dose of 2.0 mg/kg in acute and subacute studies, the level of spermatocytes with damaged synaptonemal complexes increased statistically significantly compared to control in 6.0 and 7.0 (р < 0.05) times, respectively.