Data on the transfer of artificial radionuclides from the environment to the food supply is necessary for internal dose assessment. There is a necessity for expanding and improving the available information on these factors in order to make better dose models for specific scenarios. This paper describes the results of a field experiment with broiler chickens on the transfer factor (F f) and concentration ratio (C R) for the long-term intake of 241 Am and 137 Cs with grass meal and soil. The broilers were divided into two groups, each group had nine subgroups and each subgroup had three broilers. The radionuclide concentrations in the feed and the thigh muscle, thigh bone, and liver of 54 broilers divided between the grass meal and soil groups were evaluated by gamma spectrometry for 241Am and 137Cs. The duration of feeding with "contaminated" sources ranged between 1-70 days. The equilibrium stage of 241 Am in muscle and bone occurs on the 1 st and 40 th day, respectively; for 137 Cs in muscle-30 th days of intake and for liver and bone-7 th days. For 241 Am, the liver did not reach equilibrium stage during the 70 days of intake. F f of 137 Cs in the "forage-muscle" and "soil-muscle" systems were determined as 1.9±0.3 and 0.18±0.05; F f of 241 Am in the "soil-muscle" system was-7.5×10 −5 .
Kazakhstan is known as a country with a complex radioecological situation resulting from different sources such as a natural radiation background, extensive activities of the industrial system of the former Soviet Union and a well-known testing of nuclear power weapons occurred in the Semipalatinsk Test Site (STS) area. The present study focuses on the assessment of the background of dicentric chromosomes in Kazakhstan’s population, which is the starting point in the dose assessment of irradiated people, since the baseline level of spontaneous dicentrics can vary significantly in different populations. In this context, aiming to determine the background frequency of chromosome aberrations in the population of Kazakhstan, considering the heterogeneity of natural radiation background levels of its large territory, a selection of 40 control subjects living in four cities of North, South, West and East Kazakhstan was performed. The cytogenetic study on the selected groups showed fairly low background frequency values of chromosome aberrations (0.84 ± 0.83 per 1000 cells), comparable with other data in the literature on general populations, reporting background frequency values between 0.54 and 2.99 per 1000 cells. The obtained results should be taken into account when constructing the dose–effect calibration curve used in cytogenetic biodosimetry, as a “zero” dose point, which will reduce the uncertainty in quantifying the individual absorbed dose in emergency radiological situations.
Although numerous epidemiological studies have demonstrated an increased risk of cancer and non-cancer diseases associated with acute exposures to high doses of radiation, possible effects of protracted exposures to low-to-moderate doses of radiation remain to be investigated. Several epidemiological studies have been conducted for residents living near the Semipalatinsk Test Site in the former Soviet Union who were exposed to protracted low-to-moderate doses of both external and internal radiations. However, small population size and other limitations of the previous studies preclude a precise evaluation of the health effects. An international joint study of Kazakhstan and Japan was initiated in 2001 to investigate the health effects among residents of the exposed areas based on a new large-scale cohort of the Semipalatinsk populations. In the joint study, information was obtained on the name, date of birth, sex, residential history and vital status of individuals living in the former collected, among which the vital status of 41,128 residents (30.7%) was ascertained. The completeness of the ascertainment depended on the place of residence with lower completeness for control areas mainly because of emigration. Although any analysis based on retrospective follow-up data is limited because of potential selection bias, the sub-population of our established cohort will be a useful resource for future prospective studies.
A study on radiation health effects for residents around the Semipalatinsk Nuclear Test Site has been conducted by REA of Japan and NNC of the Republic of Kazakhstan. In this study, we established a new cohort. The present paper describes the method for individual dose estimation relevant to the consequences of nuclear tests for residents in 10 villages around the test site and presents part of the results. External doses were calculated based on air dose rates reported in the literature soon after the nuclear tests. Internal doses due to inhalation were estimated based on the air concentration of radionuclides calculated from the air dose rate. Internal doses due to ingestion were estimated based on the ground deposition of radionuclides calculated based on the air dose rate. The external dose was much higher than the internal dose. The total dose varied by village, with the highest dose observed in Chermushki followed by Dolon, Sarjal, Karaul, and Akubulak. These results are in reasonable agreement with doses reported by others so far.
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