V. K. Ivanov, S. Yu. Chekin, V. V. Kashcheev, M. A. Maksioutov, K. A. Tumanov, A. F. Tsyb

Dynamics of the mortality and the mortality radiation risks among liquidators of 1986-1987 years of entrance to the Chernobyl zone is analyzed. The average dose of external gamma exposure for this cohort equals 128 mGy. The size of the cohort at the beginning of the follow-up in 1992 was 47,820 persons. For the follow-up period 1992-2006 statistically significant radiation risks of death rates are estimated: for the mortality from all causes the excess relative risk per Gy (ERR/Gy) equals 0.42 with 95% confidence interval (95% CI) (0.14 – 0.72); for the mortality from solid cancers ERR/Gy = 0.74, 95% CI (0.03 – 1.76); and for the mortality from the circulatory system diseases ERR/Gy = 1.01, 95% CI (0.51 – 1.57). Based on this estimates the risk groups were ranked among all Russian liquidators (160 thousand persons): the group of the potential radiation risk with doses more than 150 mGy (33,488 persons) and the group of high radiation risk with doses more than 240 mGy (6,054 persons).

In Russian

Ivanov V.K., Khait S.E., Kashcheev V.V., Chekin S.Yu., Maksioutov M.A., Tumanov K.A.

Dynamics of the leukaemia incidence in the cohort of 104 thousand Russian emergency accident workers (EAWs), men, over the period from 1986-2007 was examined. The average age of the EAWs at the time of their arrival at the working area was 34 years. Maximal SIR values for leukaemia in the cohort was over the 10-year period, 1990-1999, SIR values close to the unity were observed over the initial (1986-1989) and in the finite (2000-2007) periods. Radiation risk of leukaemia (excluding ChLL) was estimated for 75 thousand EAWs of the cohort with official individual external gamma-radiation doses to a whole body, accumulated over the working period. Mean radiation dose was 108 mGy, the highest dose was 500 mGy. Statistically significant (p=0.05) linear relationship between dose and leukaemia incidence was in the period (1989-1997), ERR/Gy=4.76. Over the period from 1998 to 2007 the radiation risk of leukaemia was not found. Obtained results allow us to conclude that excess leukaemia incidence possibly caused by external gamma-radiation is observed in 3-11 years after the exposure.

In Russian

Ivanov  V.K.,  Tsyb  A.F.,  Maksioutov  M.A.,  Tumanov  K.A.,  Chekin  S.Yu.,  Kashcheev  V.V., Korelo A.M., Vlasov O.K., Shchukina N.V.

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.

In Russian

Vlasov O.K., Shchukina N.V.

New approach to calculation of modified standard internal doses to thyroid and a whole body of residents of contaminated settlements based on radiometry data of 1986 is presented. The approach was used for calculation of modified standard doses for all residents added to the joint data base of the NRER and the Institute of Radiation Hygiene of St.-Petersburg. Power regressions of averaged standard doses with regard to a settlement and density of contamination with ¹³⁷Cs were practically affected neither by a region of residence nor a settlement type. Compound error of calculation of standard doses by regression dependence is 1.6-1.7. Compound error of calculation of standard doses with regard to a settlement is 2.0-2.3.

In Russian

Victor K. Ivanov, Anatoly F. Tsyb, Alexander P. Panfilov, Alexander M. Agapov, Oleg V. Kaidalov, Alexander M. Korelo, Мarat A. Maksioutov, Sergey Y. Chekin, and Polina V. Kashcheyeva

Internationally, the upper limit of acceptable individualized risk from occupational exposure for nuclear industry workers is determined by the death probability 10^-3 y^-1. The same risk value of 10^-3 y^-1 is established by the radiation safety standards currently in force in Russia. The United Nations Scientific Committee on the Effects of Atomic Radiation has proposed the formulas for estimating individualized risk of developing cancer with allowance for radiation dose, age at exposure, attained age, and sex. This methodology is first applied to estimate individualized radiation risk for Russian nuclear industry workers (49,900 persons) who were monitored for radiation exposure through the use of personal dosimeters. The estimates show that in 2006 the threshold of
10^-3 y^-1 for individualized risk is exceeded for 755 persons, which is 1.6% of all workers covered by personal dose monitoring. The excess absolute risk (EAR) and attributable risk (AR) were estimated for all cancers, solid cancers, and leukemias.

V. K. Ivanov, A. I. Gorsky, V. V. Kashcheev, M. A. Maksioutov, K. A. Tumanov

The paper presents estimates for the latent period of the induction of radiogenic solid cancers among Chernobyl emergency workers (males) living in six central regions of Russia. The analysis is based on medical and dosimetry data gathered by the National Radiation and Epidemiological Registry over the time period from 1986 to 2005. The cohort includes 59,770 persons who stayed in the exposure zone (30-km zone around the Chernobyl nuclear power plant) in 1986-1987. There were 2,718 cases of solid tumors identified during the follow-up time in this cohort. The mean radiation dose in the cohort is 0.13 Gy. The radiation risk and latent period were estimated using the method of maximum likelihood. The excess relative risk per unit dose was found to be 0.96 (95% confidence interval (CI): 0.3–1.7) and the minimum latent period for induction of solid tumors is 4.0 years (95% CI: 3.3–4.9).

Ivanov V.K., Gorsky A.I., Maksioutov M.A., Tumanov K.A., Kashcheev V.V.

The paper discusses the results of analysis of radiation risks of thyroid cancers among the Chernobyl emergency workers (living in Russia) resulting from exposure to iodine radioisotopes. Due to the lack of documented doses from this source, the characteristics of the curve of this radionuclide decay were used for analysis. The analysis was performed by two independent methods: the exposed versus unexposed (the exposed are the emergency workers who worked in the 30-km zone during the first 65 days after the accident and the unexposed are those working there later) and the regression analysis based on the maximum likelihood method using the surrogate dose (period and time of stay in the 30-km zone during ¹³¹I decay). By both methods statistically significant estimates were derived for the relative radiation risk – 1.8 (1.2; 2.8 95% CI) and for the excess radiation risk per unit surrogate dose – 2.5 (0.2; 6.5 95% CI). The obtained results indicate that the follow-up of the emergency workers in relation to this issue should be continued.

In Russian

Ivanov V.K., Zamulaeva I.A., Kashcheeva P.V., Saenko A.S., Orlova N.B., Smirnova S.G.,
Korelo A.M., Gorsky A.I., Maksioutov M.А., Vaizer V.I.

In the study forming groups of potential cancer risk from occupational exposure to radiation with molecular and radiation epidemiological approaches is discussed. Frequency of gene mutations at TCR locus was measured in 320 professionals of the State Scientific Center of the Russian Federation Institute for Physics and Power Engineering named after A.I. Leypunsky. Average accumulated dose get by the workers was 100 mSv. Due to the use of radiation epidemiological approaches to defining the workers with the value of attributable radiation risk of 10% and more it was managed to increase the portion of people with increased level of gene mutations in the group. It is noted that the obtained results are preliminary because of limited statistical power of studies.

In Russian

Kashcheev V.V., Chekin S.Y., Maksioutov M.А., Tumanov K.A., Ivanov V.K.

A dependence of radiation risk of cancers in emergency accident workers of the Chernobyl accident on their age at exposure was estimated for the first time. Excess relative risk (ERR/Gy) was found to be 1.07 (95% CI: 0.49; 1.73) in the age group of 36-65 years. The value of ERR/Gy is considerably lower and statistically insignificant in the age group of 18-35 years, it is 0.11 (95% CI: -0.58; 0.95).

In Russian