Problems of the establishment of the dose-effect relationship for risk assessment under exposure to ionizing radiation and harmful chemical substances

The aim of the study. An analysis of the problems of the development of the dose-effect relationship (DER) in the assessment of the risk under exposure to ionizing radiation (IR) and harmful chemicals (HC) on human health and proposals for improving them.

Material and methods. Problems of the development and application of the methodology for assessing the risk of exposure to IR and HC are in the area of delivering DER based on the results of biological experiments and epidemiological studies (ES). These problems are associated with such properties of the effects of exposure to IR and HCh as nonspecificity and latency, low statistical power, fragmentation of the actual information available on the studied effects, possible dependence on the level of the associated spontaneous morbidity or mortality rate. A number of DER models have been developed by national and international organizations. However, between these models, there are significant differences in the choice both of model parameters and the ratio between the multiplicative and additive dependencies on spontaneous effects. The relevance of improving DER models suitable for reliable predictive risk assessments of exposure to IR and HC remains.

Results. In modern DER models, the ratio between the multiplicative and additive dependencies on spontaneous effects was chosen by an expert way on the basis of the available results of biological experiments and ESs without sufficient rigorous justification. This was reflected in the different choice of this ratio by different developers. For a more reasonable choice of the ratio, it is proposed to consider two possibilities: 1) implementing additional targeted biological research on the molecular-cellular and organismic levels; 2) a joint analysis of the results of two independent ESs on different cohorts affected by exposure to IR or HC. For IR there is a real opportunity to solve the problem according to the second option. A specific possible method of action in the second direction and an algorithm for its implementation are proposed.

Conclusion. Current models of DER for IR and HC require further development, in particular, in terms of the relationship between multiplicative and additive dependencies in DER. A method of justifying the choice of this ratio is proposed and an algorithm for its implementation for IR is described.