The accident at the Chernobyl nuclear power plant and the problem of estimating the consequences of radioactive contamination of natural and agricultural ecological systems

Heavy radiation accidents cause long-term low-dose biota irradiation on large territories. In this situation of great importance is a correct estimation of danger of low-dose irradiation. Approaches now in use to assess the genetic consequences of irradiation are based on linear extrapolation of biological effects induced by high and medium doses to the region of low doses. However, models based on the linear non threshold hypothesis lack strong biological justification and come into conflict with the experimental data available. Our experiments with agricultural crops aimed at studying regularities in the induction cytogenetic damages using test-systems have demonstrated that the form of the dose-effect curve in the domain of low exposure values shows a pronounced linearity and the presence of a dose-independent region. A comparison of the experimentally revealed form of the empirical curve with results obtained for other objects (human lymphocytes, fibroblasts of Chinese hamster, seedlings of horse beans, etc.) allows a conclusion to be made that the relationship between the yield of radiation induced cytogenetic disturbances and dose is non-linear and universal in character, varying for different objects only in dose values at which changes in the relationship nature occur. So, the observed genetic effects in the region of low doses result from peculiarities in the cellular response to weak external action rather than damaging impact of ionising radiation or other factors of physical or chemical nature