RESUMEN
BACKGROUND: Previous studies showed an increased risk of thyroid cancer among children and adolescents exposed to radioactive iodines released after the Chornobyl (Chernobyl) accident, but the effects of screening, iodine deficiency, age at exposure and other factors on the dose-response are poorly understood. METHODS: We screened 11 970 individuals in Belarus aged 18 years or younger at the time of the accident who had estimated (131)I thyroid doses based on individual thyroid activity measurements and dosimetric data from questionnaires. The excess odds ratio per gray (EOR/Gy) was modelled using linear and linear-exponential functions. RESULTS: For thyroid doses <5 Gy, the dose-response was linear (n=85; EOR/Gy=2.15, 95% confidence interval: 0.81-5.47), but at higher doses the excess risk fell. The EOR/Gy was significantly increased among those with prior or screening-detected diffuse goiter, and larger for men than women, and for persons exposed before age 5 than those exposed between 5 and 18 years, although not statistically significant. A somewhat higher EOR/Gy was estimated for validated pre-screening cases. CONCLUSION: 10-15 years after the Chornobyl accident, thyroid cancer risk was significantly increased among individuals exposed to fallout as children or adolescents, but the risk appeared to be lower than in other Chornobyl studies and studies of childhood external irradiation.
Asunto(s)
Accidente Nuclear de Chernóbil , Radioisótopos de Yodo/efectos adversos , Neoplasias Inducidas por Radiación/diagnóstico , Neoplasias de la Tiroides/etiología , Adolescente , Adulto , Niño , Estudios de Cohortes , Relación Dosis-Respuesta en la Radiación , Femenino , Estudios de Seguimiento , Humanos , Incidencia , Masculino , Factores de Riesgo , Neoplasias de la Tiroides/patología , Adulto JovenRESUMEN
A region between Chelyabinsk and Ekaterinburg in the Southern Urals has been heavily contaminated due to operational and accidental releases from the first Soviet plutonium production facility Mayak. In 1992 and 1993, the German Federal Office for Radiation Protection organized a measuring campaign involving two Russian institutes to assist with the validation of former Soviet measurement data. The results of this measuring campaign are reported here. Environmental samples were collected from areas affected by significant radioactive releases into the Techa river, which started in 1948, and by fallout from the explosion of a fission product storage tank in 1957. Soil, sediment, water, milk and food samples were independently analysed for 90Sr, 137Cs and plutonium by the three institutes involved. This paper presents data on the present levels of environmental radioactivity. The highest contamination of areas accessible to the local population was found in the vicinity of the Techa river around Muslumovo. Activity concentration of floodplain samples reached up to 37,000 Bq.kg-1 137Cs, 5,600 Bq.kg-1 90Sr and 9.9 Bq.kg-1 Pu. Milk and potatoes from private farms in Muslumovo showed low activity in the range from 0.7 Bq.kg-1 to 25 Bq.kg-1 90Sr. The results of the three independent measurement teams showed sufficient agreement. One Russian laboratory obtained plutonium activities that exceeded the results of the other laboratories by about 20%. Contrary to the International Chernobyl Project, there was no overestimation of 90Sr activities in the Russian analyses. Therefore, the validity of earlier data sets acquired with same methodology and quality control can be considered a valuable basis for further assessments and for dose reconstruction in epidemiological projects.
Asunto(s)
Radioisótopos de Cesio/análisis , Monitoreo de Radiación , Protección Radiológica/legislación & jurisprudencia , Estroncio/análisis , Animales , Contaminación Radiactiva de Alimentos/análisis , Humanos , Leche/química , Monitoreo de Radiación/métodos , Reproducibilidad de los Resultados , Federación de Rusia , Contaminantes Radiactivos del Suelo/análisis , Contaminantes Radiactivos del Agua/análisisRESUMEN
The Southern Urals in Russia was contaminated by radioactive discharges into the Techa River (1949-1956), the Kyshtym accident (1957), and the current releases and discharges from the Mayak Nuclear Materials Production Complex. In this paper, the consequences of radioactive contamination of the Ural region are analyzed. The current content of 90Sr in the components of food chains is as follows (Bq kg(-1) wet weight): potatoes, 0.2-6.7; grain, 0.5-12.6; milk, 0.2-6.3; beef, 0.2-1.7; lake water, 0.12-1.0; river water, 0.2-8.5; fish, 7-480; mushrooms, 400-1,100; and berries, 700-16,000. The content of 137Cs is as follows: potatoes, 0.5-3.8; grain, 0.3-2.9; milk, 0.2-4.5; beef, 0.3-2.6; lake and river water, 0.002-0.019; fish, 2-32; mushrooms, 110-1,600; and berries, 150. A major fraction of the dose to humans comes from the consumption of local food products, including natural ones, which have higher contamination levels than agricultural products. The average annual dose rates in contaminated areas are (0.5-4) x 10(-4) Sv y(-1), which is lower by a factor of 10(2)-10(4) than in the periods of "acute" exposure (1950-1951 and 1957-1958). Natural organisms received very high doses up to 200-800 Gy resulting from radioactive discharges into the Techa River and the radiation accident in 1957. In all cases, including the "acute" exposure followed by the chronic irradiation, the doses to biota were by a factor of 10-10(3) higher than those to humans.
Asunto(s)
Contaminación Ambiental , Contaminación Radiactiva de Alimentos/análisis , Dosis de Radiación , Liberación de Radiactividad Peligrosa , Radioisótopos/análisis , Contaminación Radiactiva del Agua/análisis , Animales , Radioisótopos de Cesio/análisis , Peces , Agua Dulce , Geografía , Humanos , Leche , Moluscos , Federación de Rusia , Estroncio/análisis , VertebradosRESUMEN
A brief overview of the radioactive waste inventory of the 'Mayak' PA reprocessing plant, Chelyabinsk Region, Russia is given together with a description of the environmental contamination caused by its activities and the origins of contamination. The joint Russian-Norwegian field work in 1994 is described, together with the major analytical results. The field work was of a limited extent, and was not designed to include a complete mapping of the environmental contamination around the plant. The results are, however, in good agreement with the very extensive previous Russian investigations. The highest concentrations of radioactivity were found in Reservoirs 10 and 11 and at the floodplain of the upper Techa River (Asanov Swamp). Also high concentrations are found in biota, especially fish from Reservoir 10.
Asunto(s)
Guerra Nuclear , Residuos Radiactivos , Contaminantes Radiactivos del Agua/análisis , Contaminación Radiactiva del Agua/análisis , Regiones Árticas , Agua Dulce/química , Cooperación Internacional , Noruega , Liberación de Radiactividad Peligrosa , Radioisótopos/análisis , Federación de Rusia , Abastecimiento de Agua/análisisRESUMEN
In bone marrow cells of common voles living within the Eastern Urals radioactive track (EURT) and adjacent area, the frequency of chromosomal aberrations was higher than in cells of control animals. In several animals, the proportion of aberrant cells was significantly higher; cells with multiple chromosomal lesions prevailed among the aberrant cells. Frequency of chromosomal aberrations did not depend on the absorbed dose of beta-radiation. Taking into account the radiation background in trapping sites, the level of cytogenetic damage in the animals studies should be considered unexpectedly high. Outside the EURT, two voles with mutant karyotypes were caught. It was hypothesized that carriers of hereditary chromosome instability appeared in the population studies as a result of exposure to ionizing radiation.