Incidence and mortality from cerebrovascular diseases (CVD) (430-438 ICD-9 codes) have been studied in a cohort of 18,763 workers first employed at the Mayak Production Association (Mayak PA) in 1948-1972 and followed up to the end of 2005. Some of the workers were exposed to external gamma-rays only while others were exposed to a mixture of external gamma-rays and internal alpha-particle radiation due to incorporated 239Pu. After adjusting for non-radiation factors, there were significantly increasing trends in CVD incidence with total absorbed dose from external gamma-rays and total absorbed dose to liver from internal alpha radiation. The CVD incidence was statistically significantly higher among workers with total absorbed external gamma-ray doses greater than 0.20 Gy compared to those exposed to lower doses; the data were consistent with a linear trend in risk with external dose. The CVD incidence was statistically significantly higher among workers with total absorbed internal alpha-radiation doses to liver from incorporated 239Pu greater than 0.025 Gy compared to those exposed to lower doses. There was no statistically significant trend in CVD mortality risk with either external gamma-ray dose or internal alpha-radiation dose to liver. The risk estimates obtained are generally compatible with those from other large occupational studies, although the incidence data point to higher risk estimates compared to those from the Japanese A-bomb survivors. Further studies of the unique cohort of Mayak workers chronically exposed to external and internal radiation will allow improving the reliability and validating the radiation safety standards for occupational and public exposure.
Bibliographical noteFunding Information:
Acknowledgments This study was conducted with support from the Federal Medical Biological Agency (FMBA Russia) and the European Commission (EC)’s Euratom Nuclear Fission and Radiation Protection Programme, through contract FP6-516478 ‘‘Southern Urals Radiation Risk Research’’ (SOUL), State Contract No. 11.309.06.0 ‘‘Clinical Epidemiological Assessment of Radiation Risks of Somatic (Non-Cancer) and Genetic Effects of Chronic Exposure’’, and State Contract No. 11.311.09.0 ‘‘Effects of Chronic Exposure in the Mayak Workers Cohort’’. The authors also would like to express their thanks and acknowledgements to the Mayak PA Radiation Safety Department headed by Mr. E.K. Vasilenko and to the SUBI Internal Dosimetry Department headed by Dr. V.V. Khokhryakov for access to the Mayak Doses-2005 database established in the framework of the Russian-American cooperation, to the SUBI Laboratory of Epidemiology headed by Dr. M.E. Sokolnikov and personally to Dr. N.A. Koshurnikova for access to the Medical Dosimetry Registry for Mayak PA workers, and to the SUBI Occupational Health Laboratory headed by Dr. F.D. Tretyakov for access to the Cause of Death Registry for Ozyorsk residents.