[A computing laboratory-clinical system in the screening of malignant tumors: study of the state of the antioxidant system and level of cellular proliferation markers among the population from the Chernobyl AES accident area]
The author bases and describes the computing laboratory and clinical system for screening groups at a higher risk for malignant neoplasms whose incidence is likely to increase due to irradiation. Two years after the disaster the detected group at a higher risk was 2-2.4 times larger than the control group among persons who received the total irradiation dose 5 rem and over as well as among persons who are to be removed from the area polluted with radionuclides whatever the dose. As the time elapsed since the disaster increases, the number of subjects with a higher level of biomarkers also grows. It is advisable that this system be introduced in all fields of the practical health care in the polluted and control areas to carry out goal-oriented treatment and diagnostic measures in the selected population groups.
Current doses arising from external and internal pathways have been estimated for the residents of two villages, Muslumovo and Brodokalmak, alongside the Techa River, which was contaminated by radioactive releases from the Mayak production facility. The dose estimates are based on numerous environmental measurements supplemented by further human whole body measurements and studies on occupational and dietary habits of Slavic and Turkish ethnic groups. Estimated doses arise mainly from use of the contaminated floodplains alongside the Techa River. The current average annual effective dose attributable to Cs and Sr in the environment, under conditions where restrictions on some river-related activities are in place, may exceed the Russian national action level of 1 mSv only in the hypothetical critical group of herdsmen in Muslumovo. The dose to this critical group in Brodokalmak is assessed to be 3 times less than that in Muslumovo and 2 fold below the action level. The external and internal exposures give comparable contributions to the total dose in both settlements and population groups: 47% and 53% in Muslumovo and 40% and 60% in Brodokalmak, respectively. About one quarter to one half of the internal dose in adults arises from the intake of Sr. In order to avoid substantial increases in the dose received by Muslumovo residents, it is expedient to prolong the current policy of restriction of some river-related population activities in this village.
The paper deals with one of the most urgent aspects of irradiation hygiene, namely assessment of risk for irradiation-induced cancers of the thyroid. A model is described to predict high mortality rates of thyroidal cancer in the population due to the catastrophe at the Chernobyl Atomic Power Station. With the model, life-time risk rates involving sex and age at the moment of irradiation, as well as an irradiation mode.
The authors provide the results of long-term investigations of the consequences of environmental pollution from the military nuclear plant in the Southern Urals. Altogether 28,100 individuals who received substantial doses of external and internal radiation in the Techa riverside in the early fifties were entered into the study. The increase in the leukemia incidence as compared with unexposed controls has been confirmed on a statistical basis. The majority of excess cases of leukemia were recorded within the 5th to the 20th year after irradiation and may be attributed to the acute and chronic granulocytic types. The level of leukemia risk on the basis of the Techa river data is evaluated as 0.48-1.10 per 10(4) persons/years/Gy.
Because of their well-documented exposures to repeated low doses of ionizing radiation, nuclear reactor workers offer an opportunity to assess cancer risk from low-dose radiation. A cohort of all 15,619 Finnish nuclear reactor workers was established through dose-monitoring records. A questionnaire survey revealed no substantial differences in consumption of tobacco or alcohol between different exposure groups nor between nuclear power company employees and contract workers. In the follow-up for cancer incidence, no clear excess in cancer incidence was observed overall, nor was any observed in any of the specific cancer types studied. There was little evidence for an association between cancer incidence and cumulative radiation dose, but the statistical power was limited. More precise estimates will be available from an international collaborative study of nuclear industry workers, including our cohort.
Incidence of and mortality from cardiovascular diseases have been studied in a cohort of 12,210 workers first employed at one of the main plants of the Mayak nuclear facility during 1948-1958 and followed up to 31 December 2000. Information on external gamma-ray doses is available for virtually all of these workers (99.9%); the mean total gamma-ray dose (+/-SD) was 0.91 +/- 0.95 Gy (99% percentile 3.9 Gy) for men and 0.65 +/- 0.75 Gy (99% percentile 2.99 Gy) for women. In contrast, plutonium body burden was measured for only 30.0% of workers; among those monitored, the mean cumulative liver dose from plutonium alpha exposure (+/- SD) was 0.40 +/- 1.15 Gy (99% percentile 5.88 Gy) for men and 0.81 +/- 4.60 Gy (99% percentile 15.95 Gy) for women. A total of 3751 cases of ischemic heart disease (IHD), including 683 cases of acute myocardial infarction (AMI), and 1495 IHD deaths, including 338 AMI deaths, were identified in the study cohort during the follow-up period. Having adjusted for non-radiation factors, there were statistically significant increasing trends with both total external gamma-ray dose and internal liver dose in IHD incidence. The trend with internal dose was weaker and was not statistically significant after adjusting for external dose, whereas the external dose trend was little changed after adjusting for internal dose. The trend with external dose in IHD mortality was not statistically significantly greater than zero but was consistent with the corresponding trend in IHD incidence. The estimated trend in IHD mortality with internal dose was lower and was not statistically significant once adjustment was made for external dose. There was a statistically significantly increasing trend in AMI incidence but not AMI incidence with external dose. The risk estimates for IHD in relation to external radiation are generally compatible with those from other large occupational studies and the Japanese A-bomb survivors.
The nuclear explosion at Chernobyl nuclear reactor on April 26, 1986, continues to have wide political, social, and medical ramifications. Hot debris from the Chernobyl reactor covered an area of more than 5,000 square kilometers with nearly 20 million curies of radionuclides. Eleven regions with a population of nearly 17 million people, of whom 2.5 million were children below the age of 5 years, suffered some degree of radioactive contamination. These children are currently of elementary school age. One of the tragedies of the explosion is that thousands of these children are at high risk for mental retardation and learning disorders.
The Chernobyl nuclear accident on 26th April, 1986, led to a massive release of radionuclides into the environment. Although vast areas of Europe were affected by Chernobyl-related ionising radiation, the accident had the greatest impact in Belarus, Ukraine, and the Russian Federation. Epidemiological studies that have investigated the link between the Chernobyl accident and cancer have largely focused on malignant diseases in children, specifically thyroid cancer and leukaemia. There is good evidence to suggest that rates of thyroid cancer in children from the countries that were formally part of the Soviet Union have risen as a consequence of the Chernobyl accident. The findings for childhood leukaemia are less conclusive. Overall rates for this disease do not seem to have been affected by the Chernobyl-related ionising radiation, but there may be a larger risk of infant leukaemia in contaminated areas of Europe. Among adult populations, there is no strong evidence to suggest that risk of thyroid cancer, leukaemia, or other malignant disease has increased as a result of the Chernobyl accident.
Overall 806 children evacuated from the city of Pripyat were examined for the thyroid condition. The children who received a dose of more than 30 rad for the thyroid manifested primary response in the form of euthyroid hyperthyroxinemia, a high risk of the development in future of autoimmune diseases in the lack of hypothyrosis.