Chromium (VI) ions induce micronuclei and nuclear abnormalities in amphibian erythrocytes

Chromium, which is one of the heavy metals, intensively pollutes the environment as a result of human activities. The toxicity, carcinogenicity and mutagenicity of chromium (VI) have been well studied in tests on fish and mammals, and to a lesser extent on birds. The genetic hazard of chromium (VI) for reptiles and amphibians is much less studied. However, amphibians are an important component of biocenoses. Therefore, the risk of exposure to chromium as an anthropogenic pollutant should be assessed for representatives of this class of vertebrates. The aim of the work was to analyze the frequency of micronuclei formation and nuclear anomalies in erythrocytes of Bufo viridis tadpoles after exposure to chromium (VI) ions. We used concentrations of 0.025, 0.050, 0.125, 0.250, 0.375 and 0.500 mg/l and the duration of exposure 6, 12, 18 and 24 hours. Experimental conditions simulated the situation of a single discharge of industrial wastewater into water bodies to final concentrations equal to 0.5, 1.0, 2.5, 5.0, 7.5 and 10 MPC of chromium (VI) ions. As a result of the experiment, it was found that chromium ions at concentrations of 0.025 and 0.050 mg/l did not cause a statistically significant increase in the total frequencies of micronuclei and nuclear anomalies in all four variants of the duration of exposure. At concentrations of 0.125 mg/l and above, the increase in the total frequencies of the analyzed anomalies was statistically significant. Consequently, even small excess of the MPC for chromium (VI) in water bodies can increase the instability of amphibian genomes.