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PubMed2000

The Chernobyl accident and its consequences: update at the millennium.

A marked increase in the incidence of papillary thyroid cancer in children has been documented in regions of the former Soviet Union most heavily contaminated by radioactive fallout from the Chernobyl nuclear power plant accident in April 1986. Accumulation of radioactive iodines by normal iodine trapping mechanisms resulted in significant radiation doses to the thyroid gland. Although it has long been known that thyroidal radiation resulted in nuclear and chromosomal abnormalities visible by light microscopy, modern molecular biology techniques are beginning to identify much smaller alterations in chromosomal coding sequences that are associated with malignant transformation. Although stable chromosomal abnormalities can be detected in Chernobyl-associated thyroid cancers, they are much less prevalent than in thyroid cancers developing after external beam irradiation. However, several unique chromosomal breakpoints have been described in radiation-associated thyroid cancers that are not commonly found in spontaneously occurring thyroid cancer. Furthermore, activation of specific subtypes of the ret/PTC tyrosine kinase oncogene appears to be more common in radiation-associated thyroid cancers than in spontaneous thyroid cancers. In summary, thyroid cancers developing in the aftermath of the Chernobyl accident provide a unique opportunity to search for chromosomal abnormalities that may be specific for radiation-induced thyroid cancer.

Chromosome Aberrations↗
PubMed1987

Iodine-131 thyroid uptake results in travelers returning from Europe after the Chernobyl accident.

Thyroid screening measurements for 131I were performed on 58 travelers returning from Eastern and Western Europe to Boston after the Chernobyl reactor accident on April 26, 1986. The travelers consisted of both Americans arriving home after business or vacation and European nationals visiting relatives in the Boston area. For purposes of dosimetry the population was divided into three subpopulations--adult (greater than 18 yr old), children (less than or equal to 18 yr old), and two individuals, 17 and 26 wk pregnant. Seventy-four percent of the population had detectable quantities of 131I thyroid burdens, ranging from 1 nCi (37 Bq) to 900 nCi (33,300 Bq). The highest adult radiation dose equivalent was 5.18 mrem (51.8 mSv). The children, however, had considerably higher dose equivalents with one infant receiving 37 rem (370 mSv). Several other children were above 1 rem (10 mSv). The fetal dose equivalents were less than 14 mrem (140 mu Sv). The presence of rain dominated those testing positive for 131I. Radioactive fallout from the Chernobyl accident contaminated a wide range of Europe and a large population subsequently ingested radioactivity. The children exhibited the highest thyroid radiation dose equivalents of the individuals monitored in the present study. The significance of this is presently unknown.

Accidents↗
PubMedDate not supplied

Cesium ions influence cultured cell behavior by modifying specific subcellular components: the role of membranes and of the cytoskeleton.

The exposure of the epidermoid cell line A431 to different concentrations of CsCl was assessed using different methodological approaches. Two different effects were detected depending upon the concentration of the agent: at low concentrations, cell modification was represented mainly by a very pronounced cell flattening and an alteration of the cell-to-cell contacts, interpreted as an increase in cell adhesion. At higher concentrations, a clear pathogenic effect was observed that allowed the formulation of the hypothesis that specific mechanisms of toxicity at the subcellular level involving mitochondrial and cytoskeletal function can exist. In addition, membrane order parameters, as detected by electron paramagnetic resonance (EPR) spectroscopy, displayed a dose-dependent increase in membrane rigidity. Results reported here seem to suggest that cesium ions can enter the cell, modify plasma membrane integrity and alter some specific cytoplasmic components, e.g. the cytoskeleton. Considering that environmental contamination by cesium as a result of radioactive fallout is of major importance and that few data are available thus far on this matter, this study provides evidence for the possible mechanisms of action of the non-radioactive form of this ion in cells.

Cell Adhesion↗
PubMed2001

The fate of 137Cs in coniferous forests following the application of wood-ash.

In the future, it may become common practice in Swedish forestry to recycle wood-ash, a waste product of the combustion of bio-fuel. As a consequence of the Chernobyl radioactive fallout in 1986, large areas of central Sweden were contaminated. Application of recycled wood-ash, originating from contaminated areas, to a previously uncontaminated forest, risks an increase in the concentration of radioactive 137Cs. We measured 137Cs radioactivity in different parts of coniferous forests in seven field experiments. Measurements of radioactivity were made 5-8 years after an application of wood-ash equivalent to 3000 kg ha(-1). The sites, in a north-south transect across Sweden, have a background radioactivity ranging from 0 to 40 kBq m(-2), the higher levels are mainly a result of the Chernobyl fall-out. Depending on its origin, the radioactivity of the applied wood-ash ranged from 0.0 to 4.8 kBq kg(-1), corresponding to 0.0-1.44 kBq m(-2). In autumn 1999, samples were taken from the soil, field vegetation, needles and twigs and the levels of 137Cs determined. In addition, soil samples were analysed for extractable K. The highest 137Cs concentration was found in the soil. At six of the seven sites there were no statistically significant effects of wood-ash application on 137Cs activity. This was despite the fact that the wood-ash had, in one case, added the same amount of radioactivity as the background. However, at one site with intermediate 137Cs deposition (10-20 kBq m(-2)), there was a statistically significant decrease in 137Cs radioactivity in the soil, needles and twigs from the plots treated with wood-ash. The decrease in radioactivity was partly due to the fact that one of the main constituents of wood-ash is K, which is antagonistic to 137Cs. Based on our results, it appears that application of wood-ash containing 137Cs does not necessarily increase the 137Cs radioactivity in plants and soil. However, some of the observed effects could be a result of the low number of replicates used in this study.

Cesium Radioisotopes↗
PubMed1998

A dosimetric determination of 137Cs ingestion from global fallout and the related risks to Japanese.

137Cs released from atmospheric nuclear detonation tests has been transported worldwide in the environment and finally taken up by humans through various pathways. In particular, ingestion pathways are important for evaluating the human health risks caused by the chronic global low-level radioactive contamination. In this research, the mathematical model for the evaluation of the dietary intake of 137Cs and the related risks to Japanese are proposed by coupling the previously published global 137Cs distribution model with the regional models such as various food ingestion models and the model of the domestic and international supply. Predictions from the proposed model were compared with the monitoring data of 137Cs in Japanese total diet as an attempt at validation. The major findings obtained in this research include that the proposed model is promising for evaluating the risk to Japanese health caused by the dietary intake of global radioactive fallout 137Cs, the 137Cs is taken up by Japanese mostly through farm products, the ingestion of 137Cs through imported foods is increasing, the risk to the Japanese health of inducing cancer by 137Cs internal exposure reached a maximum in 1963, gradually decreasing to the lowest present level, and the risk to infants is the highest.

Animals↗
PubMed2003

Long-term genetic effects of radiation exposure.

To date, there has been little experimental knowledge on the genetic risks of human exposure to ionising radiation for humans. Recent data suggest that hypervariable tandem repeat minisatellite loci provide a useful and sensitive experimental approach for monitoring radiation-induced germline mutation in humans. Here, I review the results of studies on minisatellite mutation rates in human populations exposed to radioactive fallout after the Chernobyl accident and nuclear weapon tests in Kazakhstan.

Environmental Exposure↗
PubMed1997

The ecosystem study on Rongelap Atoll.

During the 1950's and 1960's, the Laboratory of Radiation Biology at the University of Washington carried out an intensive study of this Atoll, which was contaminated with radioactive fallout from the "Bravo shot" in 1954. This study involved many aspects of the environment and the plant and animal life: soils, land plants, marine life, birds, geology and hydrology, and human diets as well. In much of the research, the fortuitiously present radioactive isotopes, especially 137Cs and 90Sr, were tracers. Although the term "ecosystem study" was not in vogue at that time, it is clear that this was an early use of the ecosystem approach. Soil types and their development, the distribution of mineral elements in plants and soils, including predominant radionuclides, distribution and growth of native terrestrial plants in relation to topography and salinity, some aspects of the human diets, micronutrient nutrition of the coconut palm, island and islet development and stability, were given attention in the studies. Some of the findings in the various areas of study will be presented and discussed.

Animals↗
PubMed1997

A comparison of independently conducted dose assessments to determine compliance and resettlement options for the people of Rongelap Atoll.

Rongelap Island was the home of Marshallese people numbering less than 120 in 1954; 67 were on the island and severely exposed to radioactive fallout from an atomic weapons test in March of that year. Those resident on Rongelap were evacuated 50 h after the test, returned 3 y later, then voluntarily left their home island in 1985 due to their ongoing fear of radiation exposure from residual radioactive contamination. Following international negotiations in 1991, a Memorandum of Understanding (MOU) was signed in early 1992 between the Republic of the Marshall Islands Government, the Rongelap Atoll Local Government, the U.S. Department of Energy, and the U.S. Department of the Interior. In this MOU it was agreed that the Republic of the Marshall Islands, with the aid of the U.S. Department of Energy, would carry out independent dose assessments for the purpose of assisting and advising the Rongelap community on radiological issues related to a safe resettlement of Rongelap. The MOU enacted two action levels which were agreed to be used to establish whether mitigation should be considered as a condition for resettlement of Rongelap Island: (1) no individual should receive an annual dose in the future of 1 mSv or more, above that from natural background radiation, assuming that his/her diet consists of only locally produced foods, and (2) the total surface soil concentration of plutonium and other transuranic elements must be less than 629 Bq kg(-1) (averaged over the top 5 cm). Environmental radiological data and dietary information were collected over two years (1992-1993) for the purpose of predicting future potential doses to Rongelapese who might resettle. In 1994, four independent assessments were reported, including one from each of the following entities: Marshall Islands Nationwide Radiological Study; Lawrence Livermore National Laboratory; an independent advisor from the United Kingdom (MCT); and a committee of the National Research Council. All four assessments concluded that possibly more than 25% of the adult population could exceed the 1 mSv y(-1) dose level based on strict utilization of a local food diet. The purpose of this report is to summarize the methodology, assumptions, and findings from each of four assessments; to summarize the recommendations related to mitigation and resettlement options; to discuss unique programmatic aspects of the study; and to consider the implications of the findings to the future of the Rongelap people.

Adult↗
PubMedDate not supplied

[Regularities of changes in 137Cs content in milk in the long term after the Chernobyl nuclear reactor accident].

Regularities of changes in 137Cs content in cattle milk in the long term after the Chernobyl accident have been analyzed. Contamination levels of haylands and pastures, soil properties, specific features of agricultural production and time after the fallout play a crucial role in 137Cs concentration changes in animal products. Trends have been studied that reflect the influence of these factors and their significance assessed. The half-life periods of 137Cs decay in milk vary over the period of 1994 to 2000 between 7.1 and 14.8 years and approach similar periods calculated for the long term after global radioactive fallout from nuclear weapons tests.

Animals↗
PubMed1966

Lead-210 and polonium-210 in biological samples from Alaska.

The naturally occurring concentrations of lead-210 and polonium-210 in certain biological samples from Alaska are unusually high. The concentration processes are similar to those observed for artificially produced radioactive fallout. Concentrations of these nuclides are greater in Alaskan natives than they are in other United States residents.

Alaska↗
PubMed1995

Childhood thyroid diseases around Chernobyl evaluated by ultrasound examination and fine needle aspiration cytology.

Screening by ultrasound examination and fine-needle aspiration cytological biopsy (FNA) was conducted in five regions in Belarus, Ukraine, and Russia to investigate the prevalence of childhood thyroid diseases around Chernobyl. Gomel, Zhitomir, Kiev, and the western area of Bryansk are the administrative regions where severe radioactive contamination occurred. The subjects from Mogilev, where contamination was relatively low, served as controls. Among 55,054 subjects (26,406 boys and 28,648 girls), the prevalence of ultrasonographic thyroid abnormalities such as nodule, cyst, and abnormal echogenity was significantly higher in the regions with severe contamination than in Mogilev. Of the 1,396 children showing echographic thyroid abnormalities 197 were selected for FNA, and a sample was successfully obtained for diagnosis from 171 (51 boys and 120 girls) of the 197 subjects. The aspirate was insufficient for diagnosis in the remaining 26 subjects. Thyroid cancer was encountered in four children (2.3%) from the contaminated regions, two children being from Gomel. The other thyroid diseases were follicular neoplasm, 6.4%; adenomatous goiter, 18.7%; chronic thyroiditis, 31.0%; and cyst, 24.0%, suggesting that a major cause of thyroid nodularity is nonneoplastic changes, mainly chronic thyroiditis and cysts. These results will serve as an important data base for further analyses and suggest that childhood thyroid diseases, including both neoplasms and immunological disorders, are consequences of radioactive fallout.

Adenocarcinoma, Follicular↗
PubMed1990

Outcome of pregnancy in one Norwegian county 3 years prior to and 3 years subsequent to the Chernobyl accident.

Pregnancy outcome was studied in a county in Norway 3 years prior to and 3 years subsequent to the Chernobyl nuclear plant accident on 26th April 1986. More detailed analyses have been performed for the 12 months prior to and subsequent to the accident. A significant increase in the spontaneous abortion rate the first year after the accident was followed by a slight decrease during the second and third years, but figures were still higher than the period prior to the accident. The rate of legal abortions was unchanged. During the entire observation period the number of births increased continuously, with the exception of a decrease in the last 2 months of 1986 and the first month of 1987. A higher incidence of spontaneous abortions was found for pregnancies conceived during the first 3 months after the accident. This increase in the spontaneous abortion rate is noteworthy, and more especially its long-term persistence, which cannot be the result of external radiation. The internal radiation from food polluted by radioactive fallout is a possible explanation. Changes in nutrition in order to avoid polluted food may also be of importance.

Abortion, Legal↗
PubMedDate not supplied

[Analysis of the strategy for the use of protective measures in agriculture after the accident at the Chernobyl power plant].

Justification of the methodological approach to evaluating effectiveness of the countermeasure strategies in agricultural production on contaminated territories is provided. The results from a comparative analysis of strategies for protective measures in agriculture after the Chernobyl NPP accident are presented. The time between radioactive fallout and application of countermeasures is shown to be one of the main factors responsible for effectiveness of countermeasures applied.

Agriculture↗
PubMed1999

Familial occurrence of chronic neutrophilic leukaemia.

A father and son who both developed chronic neutrophilic leukaemia (CNL) are reported. The father, aged 63, had been exposed to radioactive fallout after the atomic bomb attack on Hiroshima; he presented with hepatosplenomegaly and neutrophilic leucocytosis, and died of intracerebral haemorrhage 1 month after diagnosis. 4 years later his son, then aged 44, presented with neutrophilic leucocytosis. Leukaemic transformation to acute myelogenous leukaemia (AML-M1) occurred, and he died of refractory leukaemia 4 months after the diagnosis of CNL. This is the first report of this rare disease occurring in family members; genetic effect due to radioactive poisoning was suspected in the development of CNL in these two cases.

Adult↗
PubMed1994

Inconsistencies and open questions regarding low-dose health effects of ionizing radiation.

The effects on human health of exposures to ionizing radiation at low doses have long been the subject of dispute. In this paper we focus on open questions regarding the health effects of low-dose exposures that require further investigations. Seemingly contradictory findings of radiation health effects have been reported for the same exposed populations, or inconsistent estimates of radiation risks were found when different populations and exposure conditions were compared. Such discrepancies may be indicative of differences in sensitivities among the applied methods of epidemiological analysis or indicative of significant discrepancies in health consequences after comparable total exposures of different populations under varying conditions. We focus first on inconsistencies and contradictions in presentations of the state of knowledge by different authoritative experts. We then review studies that found positive associations between exposure and risks in dose ranges where traditional notions (generalized primarily from high-dose studies of A-bomb survivors or exposed animals) would have predicted negligible effects. One persistent notion in many reviews of low-dose effects is the hypothesis of reduced biological effectiveness of fractionated low-dose exposures, compared to that of the same acute dose. This assumption is not supported by data on human populations. From studies of populations that live in contaminated areas, more and more evidence is accumulating on unusual rates of various diseases other than radiation-induced malignancies, health effects that are suspected to be associated with relatively low levels of internal exposures originating from radioactive fallout. Such effects include congenital defects, neonatal mortality, stillbirths, and possibly genetically transmitted disease. A range of open questions challenges scientists to test imaginative hypotheses about induction of disease by radiation with novel research strategies.

Animals↗
PubMed2001

Migration ability of radionuclides in soil-vegetation cover of Belarus after Chernobyl accident.

This article illustrates the experimental experience achieved in the research of the self-restoration of radioactive-contaminated natural ecosystems. The main directions of studies were: the content and geochemical stability of "hot" particles in radioactive fallout from Chernobyl accident; the physicochemical forms (water-soluble, exchangeable, mobile and fixed) of Cs-137, Sr-90, Pu-239, 240 and Am-241 in the wide varieties of soils; the biological accessibility of radionuclides and their contents in soil pore solutions; and the dynamics and migration parameters of radionuclides vertical redistribution in different landscape conditions.

Americium↗
PubMed2001

Relationships between sea-bed radionuclide activities and some sedimentological variables.

Natural radionuclides (232Th, 226Ra, 40K) and 137Cs, coming from atmospheric radioactive fallout, have been measured in sea-bed sediments of the Bay of Cádiz (South Western Spain). In this report, multivariate analysis methods have been employed to study the relationships between the activities of the radionuclides and some sedimentological variables like granulometric facies, organic content and apparent density. The correlation functions found show that it is possible to determine, with a satisfactory degree of approximation, the granulometric facies of the sediments using only radiometric information.

Geologic Sediments↗