Cytotoxic effect of technogenically contaminated soil with heavy metals and radionuclides on E. fetida earthworms

E. fetida earthworms from the laboratory population were exposed for 7 and 56 days in a substrate containing technogenically contaminated soil with metals/metalloids and radionuclides from the territory of the former radium industry. Cytotoxicity of soil was assessed by changes in the stability of lysosomal membranes of coelomocytes, the main immune effector cells of earthworms. It was shown that the analysis of the accumulation of neutral red by E. fetida coelomic cells is a sensitive tool in assessing the cytotoxicity of contaminated soil. With an increase in the concentrations of elements in the medium to sublethal, a decrease in the stability of the lysosomal membranes of coelomocytes was observed. The response of the biomarker depended on the intensity and duration of exposure. Analysis of dye accumulation by E. fetida lysosomes after 56 days of incubation in moderately contaminated substrates showed a higher sensitivity of the biomarker to the effects of soil components than in the 7-day experiment. With chronic exposure to earthworms, an increase in the concentrations of metals/metalloids and radionuclides in the soil was accompanied by a change in the distribution of subpopulations of coelomic fluid cells and a shift in the ratio towards elaeocytes and a corresponding decrease in the proportion of amoebocytes.