Determination of increased radiation risk group among Russian Chernobyl cleanup workers

One of the main tasks of the National Radiation Epidemiological Registry (NRER) is monitoring the health status of people exposed to radiation as a result of the Chernobyl accident, and providing them with targeted medical care. To optimize the use of resources dedicated to mitigating health effects of the accident, it is reasonable to identify the people at the higher radiation risk, needing the priority medical care. Radiation risk is directly proportional to radiation dose the individuals received, and also depends on the age, sex of the exposed persons and their baseline (in the absence of radiation) risk rates. Among all the people been registered in the NRER the Chernobyl cleanup workers (liquidators) received the highest radiation doses. To determine the group of higher radiation risk of solid cancer among liquidators, an estimate of the attributable radiation fraction, ARF, was used. Among the all liquidators observed in the NRER in 2020, 709 persons, 1.45%, were at the higher risk group of solid cancer, with ARF values exceeding the critical value of 15%. If the critical value of ARF drops to 10%, the group at the higher risk increases to 28% of the total number of the cohort members. The size of the group at the higher risk can be increased or reduced with the use of critical ARF values, depending on the current social and economic situations. However, according to the international experience and assessment results presented in the paper, the critical ARF value may be selected within the range between 10% and 20%.