Radiological health effects 20 years after the Chernobyl accident: Data of the National Radiation and Epidemiological Registry

This paper discusses results of the analysis of cancer incidence during 11 years of follow-up (1991–2001) for Chernobyl emergency workers residing in Russia and thyroid cancer incidence among persons living in the Bryansk oblast and exposed as children (0–17 years). The analysis for emergency workers was based on using data about the cohort of emergency workers (males) including 55,718 persons with documented external doses who worked in the 30-km zone in 1986–1987. The mean age at exposure for these persons was 34.8 years and the mean external radiation dose was 0.13 Gy. In the cohort 1370 cases of solid cancer were diagnosed. The estimated standardized incidence ratio (SIR) conforms with the control (Russia). The values of excess relative risk per 1 Gy for solid malignant neoplasms were estimated to be 0.33 (95% confidence interval: − 0.39, 1.22) (internal control). According to the census of 1989 the population of the Bryansk oblast was 375,000 people. A total of 199 thyroid cancer cases were diagnosed at cancer centers. Diagnoses were confirmed histologically for 95% of the cases. The analysis has revealed statistically significant radiation risk only for those exposed as children of 0–9 years old. It has been shown that the lower the age the higher the risk. For girls whose age at exposure was 0–4 years the excess relative risk per 1 Gy (with internal control) for the period 1991–2001 was 45.3 (95% confidence interval: 5.2, 9953).