Prospective lifetime radiation risk of cancer among Russian cleanup workers in Chernobyl

As stated in the Basic sanitary rules of radiation safety, radiation risk is one of the main characteristics of radiation safety. Before the work persons involved in cleanup operations after radiation accidents should be informed about subsequent risks to their health. However, mathematical models for radiation risk prediction and methods for its calculation are currently at the stage of scientific research and have not yet been standardized for solving practical problems of risk prediction. At the international level, UNSCEAR, ICRP and WHO developed radiation risk models on the basis of radiation-epidemiological data on survivors of Hiroshima and Nagasaki atomic bombings in August 1945. In recent decades, data on radiation-epidemiological follow-up of cohorts contained people exposed to radiation after the Chernobyl accident in 1986, in particular NRER data, have been used to identify and assess radiation risks. The radiation risk models identified from the Chernobyl cohorts of exposed individuals differ from the models identified from the Japanese cohort, which leads, respectively, to different projections of lifetime radiation risk. The purpose of this work is to compare quantitatively the possible lifetime radiation risks of cancer for a cohort of Russian liquidators of the Chernobyl accident, evaluated with radiation risk models developed by UNSCEAR, WHO and NRER. It is shown that after 2020, 1297 cases of cancer are expected in the cohort of Russian liquidators, this figure is 2.4 times higher than estimates obtained with the international models. The radiation risk model of leukemia, built on the basis of NRER follow-up data, predicts 145 cases of leukemia in the observed cohort of liquidators, which is 8 times higher than the values estimated with the use of international models. Since the liquidators of the considered cohort are generally over 50 years old, the results obtained may indicate the need to adjust the dose limits established by the current radiation safety standards based on ICRP risk models for people over 50 years old.