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PubMedDate not supplied

EPR-based dosimetry of large dimensional radiation fields (Chernobyl experience and new approaches).

On the basis of EPR signal investigations using irradiated materials as gamma-radiation sensors, the method of dimensionally quasi-continual dosimetric long cords was developed and applied in the investigation of the destroyed Chernobyl Unit-4. The study of irradiated quartz with different initial and post-irradiation defect concentrations is discussed for dosimetric practical use as well as for fundamental understanding.

Electron Spin Resonance Spectroscopy↗
PubMed1999

Distribution pattern of 90Sr and 137Cs in the Nile delta and the adjacent regions after Chernobyl accident.

Strontium and cesium contents in surface soil samples across the Nile Delta and the north coast of Egypt after the Chernobyl accident have been investigated. The concentration of 137Cs and 90Sr was determined using a high resolution gamma spectrometer based on hyperpure germanium detector (HPGe) and a liquid scintillation counter (LSC) respectively. 90Sr was determined through its decay product 90Y using Cerenkov counting. The determination of 90Sr was based on tributylphosphate (TBP) extraction of yttrium from nitric acid extract of ashed samples. The radioactivity of soils ranged between 18.5 and 2175 Bq/m2 with a mean of 652 Bq/m2 and 234 and 3129 Bq/m2 with a mean of 760 Bq/m2 for 137Cs and 90Sr respectively. An estimated absorbed dose equivalent due to the measured deposit of 137Cs was found to be 0.062 murem/h.

Cesium Radioisotopes↗
PubMed2000

The distribution of 137Cs and 90Sr in the biomass of pine trees planted in 1987-1988 in the near zone of the Chernobyl nuclear power plant.

This paper presents the results of a study, carried out in 1996, of the distributions of 137Cs and 90Sr in the biomass of a new pine plantation, planted in 1987-1988, in the near field of the Chernobyl nuclear power plant. The maximum observed concentrations were 4.2 MBq kg(-1) for 137Cs in the youngest needles and 1.1 MBq kg(-1) for 90Sr in the oldest needles. The estimation of the total absorbed doses in the different organs of the pine was also carried out, the observed doses were in the range 2 Gy yr(-1) to 16.8 Gy yr(-1); the lifetime dose for the needles (4 yr) was 44 Gy.

Biomass↗
PubMed1998

Isolation and analysis of UV and radio-resistant bacteria from Chernobyl.

The accident at the Chernobyl nuclear power station in 1986 led to the dispersal of large amounts of a variety of radioactive materials, most importantly uranium, plutonium, 137Cs, 131I and 90Sr, over very large distances estimated to reach as far as Sweden, Norway, Turkey and possibly the USA. As a consequence, the soil on which the radioactive materials fell was contaminated and the degree of contamination varied with distance from the station, the direction and strength of the wind and the amount of atmospheric scavenging by rainfall at that time. Some of the radioactive materials have left a significant impact on mankind in the form of chromosomal aberrations including trisomy, various forms of cancers and death, whilst others are still in the ground where they will remain for a prolonged period to continue to exert their effects. Likewise, microbes living in the soil and exposed to radioactive materials may have been affected in a number of ways; some perished, and others survived due to the acquisition of advantageous mutation. Six years after the accident, soil samples contaminated with different levels of radioactivity were obtained from five regions within a 30 km radius of the nuclear power plant. From these soil samples spore-forming bacilli were isolated, quantified, identified and tested for resistance to X-rays, UVC and 4-nitroquinoline 1-oxide (4NQO). As a control, spore-forming bacilli were obtained from 'Zeleny mys' (an area 50 km south-east of the power station and emitting basal levels of radioactivity). A mutant of Escherichia coli hyper-resistant to a variety of DNA-damaging agents and its parent strain were also included in the study. Analysis of results reveals that a proportion of isolates of the same species from near the power station and the E. coli mutant SA236 were more resistant to X-rays, UVC and 4NQO compared with isolates from the control site and the E. coli parent strain, KL14, respectively.

4-Nitroquinoline-1-oxide↗
PubMedDate not supplied

Evaluation of 137Cs activity in plant drugs and in some phytoderivatives from Chernobyl accident up to present (1986-1994).

The accident to the nuclear power plant of Chernobyl (in April 1986) caused a radioactive contamination in large areas of the majority of European countries. During the first transient time the fall-out phenomenon was the most important method of contamination, particularly from 131I whose relative isotopic abundance with respect to other released radionuclides was very high. Thereafter, 137Cs, owing to its long half-time and its large presence in environmental matrixes and so in the food chain, became the element on which the attention was to be focused. Plant drugs and their derivatives are, at present, of very large alimentary consumption among people. This can cause some problems to human health, so the authors have studied (from 1986 to 1994) the activity of 137Cs in a large number of drugs (about 5000) and in some industrial and home-made officinal products. Some suggestions on the Cs+,K+ ions competition in soil can also be derived.

Cesium Radioisotopes↗
PubMed2001

DNA damage evaluated by alkaline single cell gel electrophoresis (SCGE) in children of Chernobyl, 10 years after the disaster.

Using the alkaline single cell gel electrophoresis (Comet) assay, the extent of DNA damage was evaluated in leukocytes of 43 Belarussian children (16 healthy and 27 affected by thyroid cancer). Thirty-nine healthy children from Pisa (Italy) were enrolled in the study as controls. In addition to basal levels of DNA damage, leukocytes were treated in vitro with bleomycin (BLM), a radiomimetic drug, to evaluate a possible adaptive response in different groups of children. Results with the Comet assay indicated an increased level of DNA damage (P=0.037) in leukocytes of Belarussian children compared to the Italian control group. In addition, within the Belarus group, lower basal levels of DNA damage (P<0.001) were found in children with cancer compared to healthy children. Tumor affected children were living in less radiocontaminated areas (P<0.04) than the healthy children and there was a significant relationship (P=0.03) between the amount of environmental radiocontamination and DNA damage in leukocytes. There were no differences in the sensitivity of leukocytes from different groups of children to BLM, indicating the absence of an adaptive response. The lack of an adaptive response may have been due to the use of noncycling cells and/or the bleomycin dose chosen. Tests for the presence of clastogenic factors (CF) in the blood serum of children showed that 39% of the tumor affected children and 19% of the healthy children in the exposed group were positive as compared to the Italian control group (0%) (Chi-square test, P<0.04). The higher levels of genomic damage in children evaluated 10 years after the Chernobyl disaster could be related to the increased incidence of individuals with CF.

Adolescent↗
PubMed1997

Cytogenetic effects in lymphocytes from children exposed to radiation fall-out after the Chernobyl accident.

In a previous paper we reported that a group of children exposed to ionizing radiation following the Chernobyl accident exhibited an appreciable number of chromosome breaks and rearrangements reflecting the persistence of a radiation-induced damage. The results suggested that the children were still exposed to radioactive contamination through consumer foodstuff and life styles. In the present paper, 31 exposed children have been considered together with a control group of 11 children with the aim to confirm previous results. All children underwent whole-body counter (WBC) measures and conventional cytogenetic analysis. The frequency of chromosome aberrations detected by conventional cytogenetics in the group of children chronically exposed to low doses of ionizing radiation resulted in significant differences with respect to the control group. The present work suggests that, for these groups of children, even if the frequency of aberrations is very low and the observation of statistically significant differences is consequently a problem, a persistently abnormal cytogenetic picture is still present several years after the accident.

Child↗
PubMed1998

Comet assay on children's leukocytes 8 years after the Chernobyl disaster.

DNA damage, mainly single strand breaks, was evaluated by single cell gel electrophoresis, in leukocytes of 36 healthy and 14 thyroid cancer-affected children prior to radio-therapy. The children come from the Gomel region, one of the areas most heavily radio-contaminated by the Chernobyl fallout. In addition, leukocytes were treated with a challenge dose of bleomycin (BLM, 1.5 micrograms/ml), to assess the presence of an adaptive response (AR) potentially resulting from chronic exposure to radionuclides. As controls, 13 children living in Pisa (Italy) were enrolled in the study. Children with thyroid cancer show higher (p < 0.001) DNA damage than healthy ones. No difference was found between healthy children from Gomel and from Pisa. A reduction in the response to BLM was significantly linked to low plasma levels of FT4 hormone (p < 0.0001), to the presence of the tumor (p < 0.002), to being female (p < 0.02), and to a higher 137Cs body burden (p < 0.03).

Adolescent↗
PubMed1999

The distribution of chromosome damage, non-reciprocal translocations and clonal aberrations in lymphocytes from Chernobyl clean-up workers.

In this paper we determined whether the frequencies of translocations and insertions are proportional to chromosome size in peripheral blood lymphocytes from Chernobyl nuclear accident clean-up workers and healthy unexposed control subjects. The frequency of aberrations among chromosomes 1, 2 and 4 in both groups was found to be significantly different from the distribution expected on the basis of chromosome size, although the difference was only marginally significant in controls. We also determined whether differences exist in aberration frequencies measured by two scoring systems: the classical method, where reciprocal exchanges are scored as one event, and PAINT, where each break junction is scored as a single event. The two scoring systems gave highly correlated results which yielded an interpretable arithmetic relationship between frequency measurements using the two systems. Approximately 34% of all translocations were observed to be non-reciprocal, and cells bearing clones of abnormal cells were observed in 6 of 198 subjects (3.0%). Our results demonstrate that clones of abnormal cells and the presence of non-reciprocal translocations contribute to the non-proportional distribution of radiation-induced and spontaneous cytogenetic damage.

Chromosome Breakage↗
PubMed1999

Radiation hazard caused by the Chernobyl accident in inhabited areas of Ukraine can be monitored by transgenic plants.

The genetic impact of the 1986 accident at the Ukraine Chernobyl Nuclear Power Plant (NPP) on populations of living organisms has yet to be fully assessed. Monitoring of the genotoxicity of polluted soils is a key element in the disaster management program. We used Arabidopsis thaliana and Nicotiana tabacum plants transgenic for a reporter gene revealing homologous recombination to study the genetic effects of chronic low-dose radiation stemming from the soil in inhabited areas of Ukraine where contamination by the accident ranges from 1 to 40 Ci/km2. We noted a significant dose-dependent increase of homologous recombination in plants cultivated in the affected inhabited areas, proving the persistently high genotoxicity of the radioactively contaminated soils.

Arabidopsis↗
PubMed1999

Chromosome aberrations in lymphocytes and clastogenic factors in plasma detected in Belarus children 10 years after Chernobyl accident.

In 1996, 10 years after Chernobyl accident, a cytogenetic analysis was carried out to assess whether chromosome aberrant cells (CA) were still detectable in the lymphocytes and clastogenic factors (CFs) were present in the plasma of children coming from Gomel (Belarus), one of the most heavily contaminated regions. Furthermore, the possible contribution of plasmatic CFs to the amount of CA was investigated. The presence of CA was examined in the lymphocytes from 29 thyroid tumour-affected children and 41 healthy children (local controls). Thirty healthy children living in Pisa (Italy) were enrolled in the study as additional controls from an uncontaminated area. No significant difference was observed between the two control groups, whereas a significantly increased frequency of CA was found in the tumour-affected children, as compared with Gomel and Pisa controls (chi 2-test, p < 0.001). However, when soil contamination level was taken into account, the chromosome type CA frequency observed in tumour-affected children coming from the more contaminated areas (> 4 Ci/km2) resulted significantly higher than that in other children, either affected or not (p = 0.003). The presence of CFs was analyzed on the plasma ultrafiltrate from 41 children. 7/10 (70%) plasma samples from tumour-affected children and 17/23 (74%) Gomel controls resulted to possess clastogenic activity irrespective of soil contamination levels. No activity was detected in the plasma of eight Pisa controls (0%). The difference between both Gomel groups and Pisa controls was highly significant (p = 0.002). A borderline, but not statistically significant correlation (p = 0.08) was observed between basal CA frequency and CF potency, which became significant (p = 0.03) when only chromosome type of aberrations was considered. We conclude that, although the presence of CFs in the plasma of these children might be partly responsible of the cytogenetic effects observed, the main source of damage has considered to be do to the previous and/or continuous exposure to environmental radiocontaminants. Tumour-affected children may represent a subset of the population either more sensitive to clastogenic damage or exposed to higher levels of contaminants.

Adolescent↗
PubMed2003

[Meteorological data and risk assessment in France after the Chernobyl accident (26 April 1986). Historical update].

The authors indicate the origin of the data used by the French Public Health Authority in 1986 to estimate the risk of the radioactive fall out following the Chernobyl accident. The technical means developed in order to establish this data, and the precedent experience gained, are described. The principal results are given. The terms of the 28 May 1986 note to the Academy of Sciences by R. Latarjet, which concluded that the low level of this fallout did not justify any countermeasure, except the control of the imported food, are confirmed. Rational dispositions are required in order to improve the information of the population, referring to the Swedish model, which involves the intervention of the medical staff specialized in radiotoxicology, radiopathology, nuclear medicine, and especially trained.

Atmosphere↗
PubMed1996

Screening for psychiatric disorders in an area affected by the Chernobyl disaster: the reliability and validity of three psychiatric screening questionnaires in Belarus.

The reliability and criterion validity of Russian versions of three psychiatric screening questionnaire (the General Health Questionnaire, 12-item version; the Goldberg scales for anxiety and depression; and, the Bradford Somatic Inventory) were assessed in the Gomel region (Belarus), one of the most severely contaminated areas that resulted from the nuclear power plant explosion at Chernobyl in 1986. All instruments were found to have good internal reliability indices. Retest reliability of the GHQ, not tested for in the other instruments, was modest. Criterion validity, using a semi-structured interview on the basis of the Munich Diagnostic Checklist for DSM-III-R as external criterion, was good for the Goldberg scales, but modest for the two other instruments.

Adolescent↗
PubMed2003

Reduction of crop contamination by soil resuspension within the 30-km zone of the Chernobyl nuclear power plant.

A field experiment was conducted within the 30-km zone of the Chernobyl Nuclear Power Plant to analyze whether the application of mulching reduced resuspension of 137Cs contaminated soil in oat (Avena sativa) crops. In 1993, we applied a mulch treatment at a dose of 200 g m(-2), and soil resuspension was measured by estimating soil loadings onto plant surfaces from Ti concentrations in plants. In 1994, two mulch doses were applied, 200 and 50 g m(-2), and we estimated the contribution of soil resuspension by using artificial resuspension collection devices (ARC). In the 1993 experiment between 4.6 and 34.4% of the plant's total 137Cs contamination was attributed to external soil contamination. The mean amount of soil-derived 137Cs attached to vegetation was 124.7 Bq kg(-1)(plant) in control plots and 53.7 Bq kg(-1)(plant) in mulched plots. In the 1994 experiment, covering the soil with a mulch layer decreased the radiocesium content in ARC by about 70%. Results obtained in these experiments suggest that soil resuspension was a significant mechanism for plant contamination and that mulching was effective in reducing that contamination.

Agriculture↗
PubMedDate not supplied

Rapid removal of Chernobyl fallout from Mediterranean surface waters by biological activity.

The sinking of particulate organic matter from the euphotic zone is an important pathway for the vertical transport of many elements and organic compounds in the sea. Many natural and artificial radionuclides in surface waters are readily adsorbed onto suspended particles and are presumably scavenged and removed to depth on time scales commensurate with both particle sinking rate and retention time of the radionuclide on the particle. Previously, abyssal benthic organisms from the northeast Pacific were found to contain short-lived fission products which entered the sea surface as fallout from nuclear testing. The presence of these radionuclides at great depth could not be explained by Stokesian settling of small fallout particles and it was hypothesized that zooplankton grazing in the surface layers packaged these particle-reactive radionuclides into large, relatively dense faecal pellets which rapidly sank to depth. We report here data from a time-series sediment trap experiment and concomitant zooplankton collections which show conclusively that Chernobyl radioactivity, in particular the rare earth nuclides 141Ce and 144Ce, entering the Mediterranean as a single pulse, was rapidly removed from surface waters and transported to 200 m in a few days primarily by zooplankton grazing.

Accidents↗
PubMed1996

Human minisatellite mutation rate after the Chernobyl accident.

Germline mutation at human minisatellite loci has been studied among children born in heavily polluted areas of the Mogilev district of Belarus after the Chernobyl accident and in a control population. The frequency of mutation was found to be twice as high in the exposed families as in the control group. Mutation rate in the Mogilev families was correlated with the level of caesium-137 surface contamination, consistent with radiation induction of germline mutation.

Adult↗
PubMed1999

Childhood exposure due to the Chernobyl accident and thyroid cancer risk in contaminated areas of Belarus and Russia.

The thyroid dose due to 131I releases during the Chernobyl accident was reconstructed for children and adolescents in two cities and 2122 settlements in Belarus, and in one city and 607 settlements in the Bryansk district of the Russian Federation. In this area, which covers the two high contamination spots in the two countries following the accident, data on thyroid cancer incidence during the period 1991-1995 were analysed in the light of possible increased thyroid surveillance. Two methods of risk analysis were applied: Poisson regression with results for the single settlements and Monte Carlo (MC) calculations for results in larger areas or sub-populations. Best estimates of both methods agreed well. Poisson regression estimates of 95% confidence intervals (CIs) were considerably smaller than the MC results, which allow for extra-Poisson uncertainties due to reconstructed doses and the background thyroid cancer incidence. The excess absolute risk per unit thyroid dose (EARPD) for the birth cohort 1971-1985 by the MC analysis was 2.1 (95% CI 1.0-4.5) cases per 10(4) person-year Gy. The point estimate is lower by a factor of two than that observed in a pooled study of thyroid cancer risk after external exposures. The excess relative risk per unit thyroid dose was 23 (95% CI 8.6-82) Gy(-1). No significant differences between countries or cities and rural areas were found. In the lowest dose group of the settlements with an average thyroid dose of 0.05 Gy the risk was statistically significantly elevated. Dependencies of risks on age-at-exposure and on gender are consistent with findings after external exposures.

Child↗
PubMed1992

Relationships between deposition of Chernobyl originating caesium and ruthenium radionuclides and rainfall in Ireland.

Deposition data for caesium and ruthenium radionuclides in Ireland as a result of the Chernobyl accident were obtained by high-resolution gamma-ray spectrometry of soil samples taken at 111 locations throughout the country. Investigation of the relationships between deposition and recorded rainfall in relevant periods enabled an assessment to be made of the activity concentration within the plume during the wash-out phase. Detailed surveys in two regions of the country enabled a comparison to be made of the relative deposition of ruthenium and caesium isotopes. No evidence was found to suggest any difference in wash-out ratios for the two ruthenium isotopes.

Accidents↗