An Effective Microscopic Index Associated with Cell Survival and DNA Lesions for Estimating Radiation Risk

Biological radiation effects are usually estimated by epidemiological data, while the statistical effectiveness of epidemiological analysis for low dose radiation is limited. This is the reason why cellular and molecular biology data have also been employed to estimate radiation effects. However, the relationship of the adverse effects at the human scale with microscopic phenomena has rarely been investigated. Finding a microscopic index which corresponds directly to the impact of radiation on health risk would thus provide a better basis for the estimation of radiation effects. In this study, we explore to find such a microscopic index. We notice that dead cells, even if they have a number of DNA lesions, will not induce delayed effects, while survival cells that have DNA lesions would do. Therefore, we consider two indices concerning both cell survival and DNA lesions. In order to analyze the data of atomic bomb survivor, we have used four indices including two new ones proposed in the present study as well as two conventional ones, which are associated with the cell survival and the number of DNA double strand breaks (DSBs). By comparing them with the cancer incidence rate from the data of atomic bomb survivor, we find that a good correlation has been achieved for the index of the total number of DSBs in survival cells among the four indices, suggesting that this index is the best indicator of radiation effects. This new microscopic index will thus provide a good measure for estimating radiation risks and an insight into radiation effects.