Consequences of the radiation accident at the Mayak production association in 1957 (the 'Kyshtym Accident').

This paper presents an overview of the nuclear accident that occurred at the Mayak Production Association (PA) in the Russian Federation on 29 September 1957, often referred to as 'Kyshtym Accident', when 20 MCi (740 PBq) of radionuclides were released by a chemical explosion in a radioactive waste storage tank. 2 MCi (74 PBq) spread beyond the Mayak PA site to form the East Urals Radioactive Trace (EURT). The paper describes the accident and gives brief characteristics of the efficacy of the implemented protective measures that made it possible to considerably reduce doses to the exposed population. The paper also provides retrospective dosimetry estimates for the members of the EURT Cohort (EURTC) which comprises approximately 21 400 people. During the first two years after the accident a decrease in the group average leukocyte (mainly due to neutrophils and lymphocytes) and thrombocyte count was observed in the population. At later dates an increased excess relative risk of solid cancer incidence and mortality was found in the EURTC.