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PubMedDate not supplied

[Ecological consequences of radioactive pollution for soil bacteria within the 10-km region around the Chernobyl Atomic Energy Station].

The diversity of aerobic chemoorganotrophic (capable of growing on nutrient agar) bacteria in radioactive soil (0.3-17.0 microCi/kg soil) sampled in the 10-km zone around the Chernobyl Nuclear Power Plant (CNPP) was found to be lower than that observed in control, uncontaminated soil with a radioactivity of 0.002-0.006 microCi/kg soil. All the radioactive soil samples contained the bacteria Bacillus cereus and Methylobacterium extorquens or M. mesophillicum, which exhibited a high tolerance to 0.3-1.0 M hydrogen peroxide, whose action can to a certain extent simulate the effect of ionizing radiation. Some of the contaminated soil samples contained other species of chemoorganotrophic bacteria with a low tolerance to H2O2. The survival of bacteria in the Chernobyl accident zone is probably due to the functioning of mechanisms efficiently neutralizing peroxide compounds and repairing radiation-damaged DNA. The population of cellulolytic, nitrifying, and sulfate-reducing bacteria in contaminated soil was found to be 1-2 orders of magnitude less than in control soil, indicating the unfavorable effect of anthropogenic radiation on the abundance and diversity of soil bacteria.

Bacillus cereus↗
PubMedDate not supplied

[Genomic disorders in the mononuclear blood cells of those who worked in the cleanup of the accident at the Chernobyl Atomic Electric Power Station].

The results of molecular investigations of blood mononuclears from 120 clean-up workers after 7-9 years of Chernobyl accident with the total exposure radiation doses ranging from 5 to 76 cGr are presented. Structural polymorphism of the leukemia associated bcr and ribosomal RNA (rRNA) genes were studied using Southern blot hybridization. Allelic polymorphism of bcr gene with characteristic for leukemia allele distribution was detected in 16.6%. Rearrangements of rRNA genes were observed in 13% of Chernobyl accident clean-up workers.

Alleles↗
PubMed1998

[The morphogenic characteristics of human transitional-cell bladder tumors in Ukraine after the accident at the Chernobyl Atomic Electric Power Station].

A study made into the morphogenesis of transitional cell tumors of human urinary bladder in 226 patients before the Chernobyl Nuclear Power Plant breakdown (I period of investigation) and 608 patients and majority of whom have been living in those regions of Ukraine affected by contamination with radionuclides as a result of the Chernobyl accident (II period of investigation) revealed decline in the prevalence of transitional cell papillomas, younger age of patients, greater incidence of invasive varieties of moderately differentiated, poorly differentiated (high-grade) transitional cell carcinoma, an unusual frequency of transitional cell carcinoma presenting with foci of multilayer planocellular metaplasia, lymphoidocellular infiltration, recurrent inflammation, foci of necrosis and hemorrhages.

Adult↗
PubMedDate not supplied

[A dynamic assessment of the reaction of the human brain to radiation exposure (the aftermath of the accident at the Chernobyl Atomic Electric Power Station)].

The present study was aimed at the comparative assessment of electrophysiological and clinical data in persons (155 right-handed men) who took part in the Chernobyl clean-up in different periods after radiation. Dynamic evaluation of psychoneurological disorders revealed the growth of incidence and severity of cerebrovascular disturbances accompanied by the signs of organic symptoms' aggravation and encephalopathy in longer periods after radiation. The results of neuropsychological examination also showed the deterioration of patients' state manifested as growth of fatigue, cognitive defects, and emotional impairments. Analysis of the EEG parameters, including power and coherence mapping and 3-d dipole source localization analysis demonstrated the increasing number of patients with the most severe forms of EEG pathology: the "plane" type in combination with fast paroxysmal (beta-band) and slow forms of activity from 45% in 1990-92 to 63% in 1997. The "hypersynchronization" type of EEG activity was typical for the earlier period accompanied by the dominance of the pathological forms of EEG activity in mediobasal structures of the left hemisphere, and brainstem zones vs. diencephalon and the right hemisphere. The later period was characterized by decreasing coherence in symmetrical frontal and front-temporal areas of the left hemisphere, while in the early period the hypersynchronization prevailed in symmetrical central areas and in the right hemisphere. The evidence were obtained to a disconnection between the brain hemispheres. We suppose that the progressive involvement of structures of the limbic-reticular complex (especially, brainstem, mediobasal structures, and white matter) into the pathological process occurs with time in participants of clean-up of the Chernobyl disaster consequences.

Adult↗
PubMedDate not supplied

[The natural resistance of the inhabitants of Kiev 10 years after the accident at the Chernobyl Atomic Electric Power Station].

A study was made of the natural resistance status in inhabitants of Kiev over ten years after the Chernobyl power plant accident. The results obtained showed that small doses of ionizing radiation exert a negative effect on the body inducing morphological changes in leucocytes, lowering the blood absolute content of large granule-containing lymphocytes, causing decline in the level of natural killer activity, changes in leucocyte as well as lymphocyte counts. In inhabitants of Kiev, post-Chernobyl changes in the studied parameters-tend to get more pronounced with time.

Humans↗
PubMed1998

[The morphogenesis of pathological processes in the gastric mucosa in chronic gastritis in servicemen who worked in the cleanup of the aftermath of the accident at the Chernobyl Atomic Electric Power Station].

Results are submitted of a complex structural analysis of 200 gastrobiopsies taken in those subjects with chronic gastritis who took part in the elimination of the aftermath of the Chernobyl accident, as well as in patients of a control nosologic group with no history of a radiation-factor exposure. The liquidators versus control patients demonstrated morphofunctional changes in gastric mucosa as potential manifestations of induced pathomorphosis of the condition. A number of propositions have been stated concerning features of morphogenesis of pathological processes in gastric mucosa under chronic gastritis in liquidators of the effects of the Chernobyl disaster.

Biopsy↗
PubMed1998

Vitamin E and A deficiencies in children correlate with Chernobyl radiation loads of their mothers.

Essential lipid bioantioxidants (BAO) (vitamins E and A) and catabolic products of the lipoperoxide cascade (LPC) (diene conjugates, ketodienes, and carbonyls) were determined in blood plasma of children aged 11 days to three years (n = 123) who are residents of regions contaminated with radionuclides (5-40 Ci/km2 of 137Cs) discharged during the Chernobyl power plant accident. Individual antenatal radiation loads Da of children and total radiation doses of their mothers Dm were also determined as external gamma-radiation loads, which correlate with internal radiation doses for permanent residents of contaminated regions. Before examination, therapy with multivitamins containing BAO determined in this work was administered to groups of pregnant women and their children (group I, n = 48) age-matched to a group that received no therapy (group II, n = 99). In group II, reduced concentrations of vitamins E and A decreased to levels indicating severe vitamin deficiency and displayed inverse correlations with Dm and Da. However, in group I these decreases and inverse correlation were only characteristic of initially normal levels of tocopherol. In group II, increases in Dm and Da caused stress-related increases in blood levels of diene conjugates and ketodienes (which was stronger than in group I with increases in Da) and, because of this, E and A vitamin deficiencies. In group I, LPC levels inversely correlated with Dm. We found nine significant correlations of radioloads of mothers with BAO and LPC pathologies of their children. The total pathogenic effectiveness of Dm in relation to LPC and BAO of children is comparable to the effectiveness of Da, which is the most hazardous radiation load. The possibility of existence of a radiation-induced protective response mobilizing BAO from depots into the blood stream is considered. BAO therapy increased the radiation resistance of children. A hypothesis was formulated that the uptake by children of their mother's radioactive Chernobyl isotopes in amounts adequate to their radiation loads is the mechanism of correlations of Dm with long-term pathogenic effects on BAO and LPC systems of children.

Antioxidants↗
PubMedDate not supplied

[Size distribution of artificial and natural radioactive aerosols in the 30-kilometer zone of the Chernobyl AES in 1986-1996].

During 10 years after the Chernobyl accident the systematical measurings of size distributions of radioactive aerosols were conducted near the block-IV. In the ground level the active median aerodynamic diameters (AMAD) of 137Cs aerosols were ranged from 0.4 up to 1.4 microns in May, 1986. In that time the aerosol carriers of radioactive Te, Ru and I had AMAD 0.3 ... 0.5 micron. During 1987-1996 AMAD of aerosol of fission products of the Chernobyl accident was stable in range 4 ... 7 microns. Simultaneously concentrations and size distributions of natural radioactive aerosols were determined. The cosmogenic 7Be aerosols had AMAD 0.5 ... 0.7 micron. AMAD of the aerosols of daughter products of radon and thoron was found 0.4 ... 0.6 micron.

Aerosols↗
PubMed2006

Chernobyl and thyroid cancer.

The most dramatic effect of exposure to fallout from the Chernobyl accident on physical health has been the increase in thyroid cancer. When this was first reported 1,2, there was scepticism in Europe and the US, as it was not thought plausible that exposure to radio-isotopes of iodine in fallout could lead to such an increase in thyroid cancer with such a short latency. This review will discuss the lessons to be learnt from a re-examination of the reasons for the original scepticism, together with what is currently known about the factors that have influenced the development of excess thyroid cancers in those exposed, the number and type of cancers that have occurred, and the interaction between tumor morphology, molecular pathology, clinical behavior, and latent period.

Adult↗
PubMed2004

Solid cancer incidence among the Chernobyl emergency workers residing in Russia: estimation of radiation risks.

An analysis is presented of solid cancer incidence during 11 years of follow-up (1991-2001) of Chernobyl emergency workers residing in Russia. The analysis is based on data from the cohort of male emergency workers from 6 regions in Russia including 55718 persons with documented external radiation doses in the range of 0.001-0.3 Gy who worked within the 30 -km zone in 1986-1987. The mean age at exposure for these persons was 34.8 years and the mean external radiation dose 0.13 Gy. In the cohort 1370 cases of solid cancer were diagnosed and 3 follow-up periods were considered: 1991-1995, 1996-2001 and 1991-2001. The second follow-up period was chosen to allow for a minimum latency period of 10 years being characteristic of solid cancers. For risk assessment two control groups have been introduced, the first 'external' one representing incidence rates for corresponding ages in Russia in general, the second 'internal' one consisting of emergency workers. The risk estimates were based on spontaneous incidence rates of solid cancer. The estimated standardized incidence ratio (SIR) is in good agreement (95% CI) with that of the control. The values of excess relative risk per unit dose (ERR/Gy) for solid malignant neoplasms have been estimated to be 0.33 (95% CI: -0.39, 1.22) (internal control) for the follow-up period 1991-2001 and 0.19 (95% CI: -0.66, 1.27) for 1996-2001.

Chernobyl Nuclear Accident↗
PubMed2004

Solubility of airborne radioactive fuel particles from the Chernobyl reactor and implication to dose.

Airborne particles of nuclear fuel from the Chernobyl reactor that had been collected on air filters and stored, were characterised using in vitro dissolution tests to assess effective doses after their inhalation. As solvent, the Gamble biological fluid was used to simulate lung fluid. The solubility of the measured radionuclides decreased in the order (137)Cs>(90)Sr>>(241)Am>or=(239+240)Pu in the simulated lung fluid. The dissolution rate constant of e.g. (239+249)Pu ranged from 0.72 to 5.4 x 10(-6) g x cm(-2) d(-1) and decreased (for all nuclides) with increasing particle size as predicted from theoretical considerations. Considering the inhalation dose, decreasing dose with size and increasing doses with lower solubility may partly counterbalance each other for (137)Cs and (90)Sr. On the other hand, for (239)Pu and (241)Am larger particles and associated lower solubility both change the resulting dose in the same direction towards lower values. The comparison of the experimentally determined dose coefficients with ICRP values indicates that nuclear fuel particles closely resemble type M material characteristics for (137)Cs and (90)Sr and type S material characteristics for (239)Pu and (241)Am.

Aerosols↗
PubMed2004

Micronucleus formation in lymphocytes of children from the vicinity of Chernobyl after (131)I therapy.

After the Chernobyl accident a statistically significant increase in the number of children with thyroid tumours was observed. In this study 166 children with and 75 without thyroid tumours were analysed for micronucleus formation in peripheral blood lymphocytes using the cytochalasin B approach. The following factors did not significantly affect micronucleus formation: gender, age at the time of the first (131)I treatment, tumour stage, tumour type, or metastases; a statistically significant increase in the number of micronuclei, however, was observed for the residents of Gomel compared to other locations, such as Brest, Grodno, and Minsk. The children with tumours received (131)I treatment after surgical resection of the tumours. This gave us the opportunity to systematically follow the effect of (131)I on micronucleus formation. A marked increase was observed 5 days after the (131)I treatment followed by a decrease within a 4-7 months interval up to the next application, but the pre-treatment levels were not achieved. Up to 10 therapy cycles were followed each including an analysis of micronucleus formation before and 5 days after (131)I application. The response of the children was characterised by clear individual differences and the increase/decrease pattern of micronucleus frequencies induced by iodine-131 was correlated with a decrease/increase pattern in the number of lymphocytes.

Adolescent↗
PubMed2005

Long-term development of the radionuclide exposure of murine rodent populations in Belarus after the Chernobyl accident.

As a determinant of the associated health risks, the behavior of radionuclides in natural ecosystems needs to be better understood. Therefore, the activity concentration of various long-lived radionuclides released due to the Chernobyl accident, and the corresponding contributions to the whole-body dose rate, was studied as a function of time in mammalian indicator species inhabiting the natural forest ecosystems of Belarus, the bank vole (Clethrionomys glareolus) and the yellow-necked mouse (Apodemus flavicollus). The activity concentrations of 137Cs, 134Cs, 90Sr, 238Pu, 239,240Pu, 241Pu and 241Am in soil and in animals were measured at five monitoring sites with different ground deposition of radionuclides at different distances from the destroyed reactor. The observed temporal pattern of the radionuclide activity concentration in the studied animal populations reflects the changes in biological availability of these isotopes for biota, mostly due to fuel particle destruction and appearance of dissolved and exchangeable forms of radionuclides. The time course of 134+137Cs activity concentrations in animal populations appeared as a sequence of increase, peak and decrease. Maximal levels of radiocesium occurred 1-2 years after deposition, followed by an exponential decrease. Concentrations of incorporated 90Sr increased up to the tenth year after deposition. The activity concentrations of transuranic elements (238Pu, 239,240Pu, 241Pu and 241Am) were much lower than those of the other radionuclides, in the studied animals. A considerable activity of 241Am in animals from areas with high levels of contamination was firstly detected 5 years after deposition, it increased up to the tenth year and is expected to increase further in the future. Maximal values of the whole-body absorbed dose rates occurred during the year of deposition, followed by a decrease in the subsequent period. Generally, this decrease was monotonic, mainly determined by the decrease of the external gamma-ray dose rate, but there were exceptions due to the delayed maximum of internal exposure. The inter-individual distributions of radionuclide concentrations and lifetime whole-body absorbed doses were asymmetric and close to log-normal, including concentrations and doses considerably higher than the population mean values.

Animals↗
PubMed2006

Transgenerational accumulation of radiation damage in small mammals chronically exposed to Chernobyl fallout.

The purpose of this investigation has been the analysis of the long-term development of biological damage in natural populations of a model mammalian species, the bank vole (Clethrionomys glareolus, Schreber), which were chronically exposed to low doses of ionizing radiation over 22 animal generations within 10 years following the Chernobyl accident. The time course of the biological end-points (chromosome aberrations in bone marrow cells and embryonic lethality) was compared with the time course of the whole-body absorbed dose rate from external and internal exposure in the studied populations inhabiting monitoring sites in Belarus with different ground deposition of radionuclides. The yield of chromosome aberrations and, in lesser degree, embryonic lethality was associated with the radionuclide contamination of the monitoring areas in a dose-dependent manner. As a main feature of the long-term development of biological damage under low dose rate irradiation, permanently elevated levels of chromosome aberrations and an increasing frequency of embryonic lethality have developed over 22 animal generations. This contrasts with the assumption that the biological damage would gradually disappear since in the same period of time the whole-body absorbed dose rate decreased exponentially with a half-value time of about 2.5-3 years. Furthermore, gravid females were captured, and their offspring, born and grown up under contamination-free laboratory conditions, showed the same enhanced level of chromosome aberrations. Therefore the authors suggest that, along with the biological damage attributable to the individual exposure of each animal, the observed cellular and systemic effects reflect the transgenerational transmission and accumulation, via genetic and/or epigenetic pathways, of damage attributable to the chronic low-dose rate exposure of the preceding generations of animals. They also suggest that the level of the accumulated transmissible damage in the investigated populations will decrease in future due to the further recession of the chronic exposure and as a consequence of selection processes.

Animals↗
PubMed2005

Ecological lessons from the Chernobyl accident.

The Chernobyl nuclear accident in 1986 not only caused serious ecological problems in both the Ukraine and Belarus, which continue to the present day, but also contaminated a large part of the higher latitudes of the northern hemisphere. In this paper an overview is given of the latter problems in upland UK, where ecological problems still remain some 17 years after initial contamination. Following deposition of radiocaesium and radioiodine in May 1986, measurements of radioactivity in grass and soil indicated a rapidly declining problem as the radioiodine decayed and the radiocaesium became immobilised by attachment to clay particles. However, these studies, as well as the advice received by the Ministry of Agriculture, Fisheries and Food, were based on lowland agricultural soils, with high clay and low organic matter contents. The behaviour of radiocaesium in upland UK turned out to be dominated by high and persistent levels of mobility and bioavailability. This resulted in the free passage of radiocaesium through the food chain and into sheep. Consequently the Ministry banned the sale and movement of sheep over large areas of upland Britain, with bans remaining on some farms to the present day. Present day predictions suggest that these bans will continue in some cases for some years to come. The causes of radiocaesium mobility in upland areas have subsequently been the subject of intense investigation centred around vegetation and, in particular, soil characteristics. Soil types were identified which were particularly vulnerable in this respect and, where these coincided with high levels of deposition, sheep bans tended to be imposed. While much of the earlier work suggested that a low clay content was the main reason for continuing mobility, a very high organic matter content is now also believed to play a major role, this being a characteristic of wet and acidic upland UK soils. The overall message from this affair is the importance of a fundamental understanding of biogeochemical pathways in different ecosystems when attempting to predict the impacts of large-scale contamination.

Animals↗
PubMed2005

A prognostic estimation of the area contaminated with alpha-emitting transuranium isotopes in Belarus following the Chernobyl accident.

As a result of the Chernobyl accident, some regions of Belarus have been contaminated with the plutonium isotopes (238,239,240,241)Pu. Considering the importance of the environmental impact of the alpha-emitting radionuclides we have carried out a prognostic estimation of the area contaminated with (238,239,240)Pu and (241)Am (the latter being a decay product of (241)Pu) in Belarus. The calculations were made using measurements of (238,239,240)Pu activity concentrations in soil samples from about 600 settlements in the affected region, together with the estimated activity ratio A((241)Am)/A((238,239,240)Pu). The area contaminated with alpha-emitting transuranium isotopes predicted for the year 2006 has been compared with that estimated for 1986. The results show that by 2006, the area of inhabited districts where contamination with (238,239,240)Pu and (241)Am exceeds the threshold level of 740 Bq/m(2), will be 3.7 times larger, reaching approximately 3.5 x10(3)km(2). Of this, almost 20% will have a contamination level of 1850--3700 Bq/m(2).

Americium↗
PubMed2005

Comparative radiation impact on biota and man in the area affected by the accident at the Chernobyl nuclear power plant.

A methodological approach for a comparative assessment of ionising radiation effects on man and non-human species, based on the use of Radiation Impact Factor (RIF) - ratios of actual exposure doses to biota species and man to critical dose is described. As such doses, radiation safety standards limiting radiation exposure of man and doses at which radiobiological effects in non-human species were not observed after the Chernobyl accident, were employed. For the study area within the 30km ChNPP zone dose burdens to 10 reference biota groups and the population (with and without evacuation) and the corresponding RIFs were calculated. It has been found that in 1986 (early period after the accident) the emergency radiation standards for man do not guarantee adequate protection of the environment, some species of which could be affected more than man. In 1991 RIFs for man were considerably (by factor of 20.0-1.1 x 10(5)) higher compared with those for selected non-human species. Thus, for the long term after the accident radiation safety standards for man are shown to ensure radiation safety for biota as well.

Animals↗
PubMed2005

Estimation of doses received in a dry-contaminated residential area in the Bryansk region, Russia, since the Chernobyl accident.

In nuclear preparedness, an essential requirement is the ability to adequately predict the likely consequences of a major accident situation. In this context it is very important to evaluate which contributions to dose are important, and which are not likely to have significance. As an example of this type of evaluation, a case study has been conducted to estimate the doses received over the first 17 years after the Chernobyl accident in a dry-contaminated residential area in the Bryansk region in Russia. Methodologies for estimation of doses received through nine different pathways, including contamination of streets, roofs, exterior walls, and landscape, are established, and best estimates are given for each of the dose contributions. Generally, contaminated soil areas were estimated to have given the highest dose contribution, but a number of other contributions to dose, e.g., from contaminated roofs and inhalation of contaminants during the passage of the contaminated plume, were of the same order of magnitude.

Air Pollutants, Radioactive↗