Radiation Exposure and Cancer Mortality in Populations Living Around the Semipalatinsk Nuclear Test Site in Kazakhstan.

Introduction. Mortality rates from malignant neoplasms can be considered a key marker of adverse environmental impacts. The aim of this study was to assess the association between exposure to ionizing radiation and the risk of mortality from malignant neoplasms among the population of Kazakhstan living in areas adjacent to the Semipalatinsk Nuclear Test Site (SNTS). Materials and Methods. The main source of data used in this study was the mortality sub-register of the population living in territories adjacent to the Semipalatinsk Nuclear Test Site (SNTS). The main study group included residents of the Abay District (n = 1300) and Beskaragay District (n = 414). In total, 478 residents of the Kokpekty District, where the radiation dose was minimal, were included in the control group. The median effective radiation dose was 864 mSv for the population of the exposed group, whereas in the control group, it was 67 mSv. Results. The highest RR values were observed in the periods 1965-1969 (RR = 6.14; 95% CI: 4.04-9.34) and 1970-1974 (RR = 6.14; 95% CI: 4.19-8.99). Age-standardized mortality rates (ASMR) in the study group were significantly higher than those in the control group. A dose-response relationship was established: with each 10.0 mSv increase in radiation dose, the risk of cancer mortality increased by 0.9% (OR = 1.009; 95% CI: 1.008-1.010; p < 0.001). Conclusions. The obtained results indicate a significant association between long-term exposure to ionizing radiation due to testing at the Semipalatinsk Nuclear Test Site and increased cancer mortality among the population of adjacent territories.