Identification of group of radiation risk on mortality from diseases of circulatory system among Russian recovery operation workers of the Chernobyl accident

The circulatory system diseases (CSD) are the leading cause of peoples’ death globally. Therefore the assessment of radiation risk of mortality for CSD is the most important task for radiation epidemiology, especially in low dose range (below 1 Gy). The main purpose of the study is identification of the group of potential radiation risk of death from CSD among Russian Chernobyl recovery operation workers (liquidators). The object under study is the cohort of liquidators with known individual doses of external gamma exposure of whole body. The group of potential risk is identified by values of excess relative risk (ERR) and relative risk (RR) estimated in the cohort of 134 thousand people, the average radiation dose is 0.11 Gy, maximum individual dose is about 1 Gy. For the period of follow up from 1986 through 2012 12400 deaths were caused by CSD. The group of potential radiation risk comprises of the liquidators with accumulated doses 0.15 Gy and above, they arrived in the Chernobyl exclusion zone in the first year after the accident and stayed there less than 6 weeks. The total size of the identified group was 9.5 thousand people (7% of the cohort members). In the group of potential radiation risk the statistically significant value of RR is 1.44 (95% CI: 1.25; 1.66), average accumulated dose is 0.23 Gy. In this risk group 31% of deaths from CSD should be considered as associated with radiation. In the beginning of 2013 the size of the group of potential radiation risk was 6155 liquidators. For remained life about 950 radiation induced deaths from CSD are expected. Adherence of liquidators of the risk group to prevention and control of circulatory system diseases would significantly decrease years of life lost due to radiation exposure in this cohort.