Problem of thyroid cancer incidence in Russia after the Chernobyl accident: assessment of radiation risks, 1991-2008 follow-up period

«Radiation and Risk», 2010, vol. 19, no. 3, pp.33-58

Authors

Ivanov V.K. – Chairman of RSCRP, Deputy Director, Corr. Member of RAMS. Medical Radiological Research Center of the Russian Ministry of Health and Social Development, Obninsk. Contacts: 4 Korolyov str., Obninsk, Kaluga region, Russia, 249036. Tel.: (495) 956-94-12, (48439) 9-33-90; e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. .
Tsyb A.F. – Director, Academician of RAMS. Medical Radiological Research Center of the Russian Ministry of Health and Social Development, Obninsk.
Maksioutov M.A. – Head of Laboratory, Cand. Sc., Tech. Medical Radiological Research Center of the Russian Ministry of Health and Social Development, Obninsk.
Tumanov K.A. – Research Assistant. Medical Radiological Research Center of the Russian Ministry of Health and Social Development, Obninsk.
Chekin S.Yu. – Senior Researcher. Medical Radiological Research Center of the Russian Ministry of Health and Social Development, Obninsk.
Kashcheev V.V. – Senior Researcher, Cand. Sc., Biol. Medical Radiological Research Center of the Russian Ministry of Health and Social Development, Obninsk.
Korelo A.M. – Lead. Programmer; Vlasov O.K. – Head of Laboratory, D. Sc., Tech. Medical Radiological Research Center of the Russian Ministry of Health and Social Development, Obninsk.
Shchukina N.V. – Research Assistant. Medical Radiological Research Center of the Russian Ministry of Health and Social Development, Obninsk.

Abstract

Joint analysis of thyroid cancer incidence in Bryansk, Kaluga, Oryol and Tula oblasts from 1981 through 2008 was made for the first time. The average size of population of the oblasts in those years was 5.1 million people. According to data of the National Radiation and Epidemiological Registry 9120 thyroid cancer cases were detected for that period. Mean-rayon thyroid doses were used for the analysis. Affected rayons of Bryansk, Kaluga, Oryol and Tula oblasts were arranged into 4 groups in accordance with radiation dose: <10 mGy; [10, 20) mGy; [20, 50) mGy; 50 mGy and above. Crude and age-adjusted incidence rates, as well as standardized incidence ratio (SIR) were used for the analysis. For the follow-up period the number of annually detected new thyroid cancer cases in the affected oblasts increased by about 6 times, despite the reduction of the size of population. Dynamic of changes in a crude incidence rate in the oblasts within the follow-up period showed linear character. Increase in a crude incidence rate for the whole period of follow-up was shown in nearly all age groups. In most age groups resided in territories with mean-rayon thyroid doses of 50 mGy and more the crude incidence rate was higher than that in age groups in other territories. In all groups arranged in relation to sex and age at the time of the accident the SIR value from 1991 through 2008 was statistically significant and exceeded 1, population of Russia was considered as control. The SIR was 6.2 in groups of boys and 3.1 in girls groups in the period of 1991-2000. In adolescent and adult groups SIRs ranged between 0.9 and 1.9 in the same period. With the use of individual data of the Russian National Medical and Dosimetric Registry statistically significant relationship between dose and thyroid cancer incidence in those exposed as children and adolescents (0-17 years of age) was showed (ERR/Gy=3.22; 95% CI (1.56; 5.81)). It was established that the excess relative risk per unit dose (ERR/Gy) for boys is 2.9 times higher than for girls.

Key words
Chernobyl accident, territory contaminated with radionuclides, population, thyroid cancer, incidence of disease, crude incidence rate, standardized incidence ratio, excess relative risk.

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