Analysis of the contribution of forest pathways to the radiation exposure of different population groups in the Bryansk region of Russia

The experience gained in the aftermath of serious radiation accidents shows that forests are an important source of external and internal exposure of the affected population. This paper presents the results of an assessment of the major radiological consequences for forests of Russia, most heavily contaminated after the Chernobyl nuclear power plant (ChNPP) accident. Illustrated in the Novozybkovsky district of the Russian Federation, the significance of different forest exposure pathways is estimated and the doses resulting from forest pathways are compared with the doses from agricultural products. It has been found that the contribution of mushrooms and berries to the internal doses of the population, relative to the doses from agricultural products, varied from 10–15% in 1987 to 40–45% in 1996. The results indicate large differences in internal exposure of members of the ”critical groups” and ”normal population”, increasing with time after deposition. Data are presented that give information on the contribution of forests to the collective doses of inhabitants of the area under consideration. It has been shown that for 10 years after the accident (1987–1996), the contribution of forest products to the collective dose of the rural population living in contaminated forests of the Novozybkovsky district, amounts to about 20% (213 person Sv) of the total collective dose of internal and external exposures. However, a potential impact of these products including the dose from exported products is much higher and might reach 659 person Sv. It has been found that in the long-term after the ChNPP accident, serious attention should be given to forest countermeasures, and restoration strategies should be selected on the basis of a combined analysis of the effectiveness of forest and agricultural countermeasures. Received: 16 March 2000 / Accepted: 10 September 2000     

To the 20th anniversary of the Chornobyl accident study of vitamin status and provision with micro- and macroelements of limited groups of people at different time periods since the accident at Chornobyl nuclear power plant

Results of the study of the provision with vitamins and some micro- and macroelements of limited groups of people, who suffered from the accident at the Chornobyl nuclear power plant (ChNPP), which have been carried out by Ukrainian and Russian scientists during various periods after the accident, are generalized in the paper. Persons which participated in liquidation of the accident and lived during the accident in the territory, adjoining to Pripyat (the Kyiv region, town of Slavutich), people which worked at the object "Shelter" and ChNPP were involved in the inspection. It was noted, that in 1-4 years after the ChNPP accident in blood of liquidators the biochemical parameters displaying security of their organism by vitamins A and B1, remain lower in comparison with the same parameters in a group of relatively healthy persons which were not affected by the accident (control), that testifies to stable metabolic disturbance in the organism of people under irradiation influence. Selective inspection of the vitamin status of ChNPP and object "Shelter" personnel in 1992 has shown, that provision with vitamins C, B1, B2, B6 of the overwhelming majority of these people (67-91%) are much below the norm. Deficiency of vitamins C, B1, B6, folate and selenium is also revealed in an organism of 50-90% of women and children living in Slavutich. Deficit of vitamins in most of persons was characterized by polyhypovitaminoses, that is a combination of several group B vitamins deficiency at simultaneously low provision with selenium, and in a part of women and children--by low amount of iron. The results of long-term complex studies by groups of authors give evidence on importance and urgency of formulation and execution of International program on optimisation of nutrition, micronutrition status and health among population of affected areas in Ukraine, Bielorus' and Russia.     

Cytogenetic and carcinogenic effects in liquidators of Chernobyl accident

A tendency of the increasing frequency of malignant neoplasms in liquidators at low radiation doses was found. The dose-effect dependence of the frequency of radiation markers (dicentric chromosomes) in lymphocytes of peripheral blood was revealed only in a group of liquidators of the ChNPP accident with malignant neoplasms in remote terms.     

Modelling of 137Cs migration in agroecosystems under safety and rehabilitation measures

Mathematical model describing dynamics of 137Cs transfer in agroecosystems under rehubilitation measures on arable, haylands, pastures and natural meadow ecosystems is presented. Possibilities of the model application for prediction of the radionuclide content in agricultural production and estimation of efficiency of countermeasures in region of the ChNPP accident are shown.     

A comparative analysis of the impact on biota and man in the 30 km zone of the Chernobyl NPP

A methodological approach is described for a comparative assessment of ionizing radiation effects on man and biota, based on the use of indices of radiation impact--ratios of actual exposure doses to environmental objects (including humans) and critical ones. As such doses, standards limiting radiation exposure and doses at which phenotypical effects were absent after the Chernobyl accident were employed, respectively for man and biota. For the test site chosen within the 30 km ChNPP zone (region of the Borshchovka settlement), dose burdens to reference biota species and the population (with and without evacuation) and the corresponding radiation impact indices were calculated. For the long term period after the accident radiation safety standards for man are shown to ensure radiation safety for biota as well. At the same time in the early period after the accident the emergency regulations do not guarantee adequate protection of nature, some species of which can be subject to irradiation more than man, even if countermeasures like evacuation are not applied. A conclusion has been made on the necessity of a more detailed and comprehensive analysis of situations when the anthropocentric principle "if radiation standards protect man then biota are also adequately protected" is violated.     

Dynamic study of the cytogenetic effects in blood lymphocytes from humans living in the Chernobyl Atomic Energy Station exclusion zone without permission

The cytogenetic examination of a group of people, self-residing in ChNPP Exclusion Zone with soil contamination density 137Cs 74-477 kBq/m2, 90Sr 33-289 kBq/m2, 238, 239 + 240Pu 1.5-10.0 kBq/m2, was conducted in 1998-1999 and also 2001. It is shown, that after 12-15 years of the accident the level of chromosome damages in Zone self-residents' lymphocytes detected by a routine analysis is higher then at the residents of control Yagotin district, Kiev region and comes to a plateau. Lymphocytes with multiple chromosome damages are detected. The probability of its transuranium elements induction which are present in the Zone is discussed at present.     

The role of cytogenetic examination for prognosis of remote consequences of irradiation

Correlation between the level of somatic pathology and cytogenetic characteristics of blood was analyzed in a group of liquidators of the accident at the Chernobyl Nuclear Power Plant (ChNPP). A statistically significant correlation was found between the occurrence of cardiovascular diseases and the level of chromosome aberrations (total frequency of chromosome aberrations, frequency of dicentrics and centric rings, frequency of chromatid aberrations). The results obtained are of great importance for the substantiated prediction of the development of postradiation pathologies.     

Transgenerational genomic instability in children of liquidators of the accident at the ChNPP (cytogenetic and immunogenetic characteristics)

A complex of cytogenetic and of immunogenetic study of the state of the lymphocyte genomes in the liquidators of the ChNPP accident and their unirradiated children has been carried out for the first time. Increased frequencies of the chromosome aberrations, of gene mutations (TCR mutations) and of predictors of apoptosis (cells with CD95+ immunophenotype) have been revealed in both generations. The analysis of correlations between the parameters under study has demonstrated distinctive features characteristic of induction of genomic instability in the organism of unirradiated children as compared to their fathers--liquidators directly exposed to radiation. Individual variability of genome destabilization were observed by all criteria used and manifested themselves in the diverse spectrum of transgenerational mutational effects and in different levels of their expression. The results obtained demonstrate the necessity of integral evaluation of the state of the genome using several genetic criteria to reveal transgenerational genomic instability in children of a special category--the offsprings of irradiated parents.     

Genetic effects in plant populations in the zone of the Chernobyl accident

During 6 years, starting from 1986, the monitoring of the dynamics of the frequency of embryo lethal and of chlorophyll mutations was carried out in arabidopsis populations in areas with different levels of radioactive contamination by the Muller embryo-test in the 30 km of ChNPP. The dose rate of chronic irradiation in the examined areas varied from 0.014 to 17 nA/Kg. Monitoring of the dynamics of the mutation process in natural arabidopsis populations showed the correlation between the level of the mutation process and the dose rate of chronic irradiation. The genetic effects of different levels of radioactive contamination were estimated by determining the frequency of mutations occurred in this generation and by calculating the dose of irradiation of one was found. That the dependence of the mutation frequency on the dose of irradiation presents a power function with a power index less 1, which suggests a higher efficiency of low radiation doses per unit dose. Possible explanations of this phenomenon are considered in the work. The studies of cytogenetic effects in chronically exposed Crepis tectorum populations in the zones of the Chernobyl accident showed that starting from the second year after the Chernobyl disaster there appeared plants with an altered karyotype and their frequency of chromosome aberrations correlates in root meristem cells.     

Substantiation of radio-ecological monitoring of forest ecosystems at various stages after the accident radioactive fallout

This study analyzes the long-term dynamics of distribution ofradionuclides in forest ecosystems. Three stages in the formation of radio-ecological situation in the forests are distinguished. Proposals for optimization of sampling for radio-ecological monitoring of forest ecosystems at various periods after a radiation accident are formulated.     

The criteria of identification of "critical" populations in aquatic radiochemoecology

Data on chromosome mutagenesis levels in populations of aquatic organisms in the Black and the Aegean Seas, the Danube and the Dnieper Rivers, the 30-km zone of ChNPP are presented. The highest level of mutagenesis was observed in hydrobionts populations in the 10-km zone of the ChNPP. The obvious damaged effects of ionizing radiation were noted only in these populations. The comparison of the adaptation rate of aquatic crustaceans and worms populations with different reproduction modes was made. It is found that the studied species with sexual reproduction have higher rate of adaptation to the pollution in comparison with species with prevalent asexual reproduction. Hypothetic mechanisms of population adaptation are discussed. On the basis of species and populations characteristics, the criteria for the identification of "critical" populations (species) and an algoritm of ecological risk assessment for them are proposed.     

Genotype dependence of cytogenetic and epidemiological characteristics in the liquidators of the accident at the ChNPP

The dependence of the level of unstable chromosome aberrations and nononcological diseases on the genotype in 57 liquidators of the ChNPP accident was studied. Candidate genes presumably affecting radiosensitivity were highly polymorphic loci of xenobiotic detoxication genes (glutathione-S-transferases GSTM1, GSTT1, GSTP1) and the 5,10-methylenetetrahydrofolate reductase gene (MTHFR) involved in DNA methylation and synthesis. An increased frequency (0.014 +/- 0.001 per cell) of unstable chromosome aberrations, including radiation-specific dicentrics and centric rings (0.0015 +/- 0.0002 per cell), has been found to be preserved in the group of liquidators examined in 2006-2007. No associations of polymorphism for each of the studied genes with cytogenetic parameters were revealed. Increased frequencies of chromosome aberrations were recorded in homozygous carriers of a deletion at the GSTM1 locus in combination with homozygosity for minor alleles at the MTHFR and GSTP1 loci (p = 0.00002 and p = 0.0233, respectively). The number of homozygous carriers of the minor allele GSTP1 was increased among patients with chronic obstructive pulmonary disease and in liquidators with acute circulation disturbances (p = 0.014 and p = 0.04, respectively). Double homozygotes for GSTM1 and GSTT1 deletions were significantly more frequent among subjects with benign tumors (cysts, polyps, p = 0.015) and with benign thyroid tumors (p = 0.017). This genotype has proved to be protective for patients with severe cardiovascular diseases (acute circulation disturbances, p = 0.027).     

The epidemiological analysis of monitoring of the immune status in liquidators of consequences of the Chernobyl accident for early identification of risk groups and diagnostics of oncological diseases. Report 2. Dependence of frequency and changes in the immune status on risk factors of radiation accident

Malignant neoplasms (MN) have been found to develop most frequently in the liquidators of entry into the ChNPP zones in 1986 (43.75%), as well as among the liquidators who worked for long, one quarter of whom participated in liquidation of the consequences of failure (LCF) in 1986. Specific features of the immune status depending on the timing of participation in LCF and the year of entry into the ChN PP zone have been established. Changes in the immune system in the persons with a confirmed diagnosis of MN who took both a non-permanent and permanent part in liquidating the consequences of the ChNPP failure in 1986 had the same character of deviations and differed in the magnitudes of deviations of immunological parameters. Continuous participation in the period of extreme conditions and a greater exposure to the radiation factor led to the increased content of CD8(+)-T-cells, CD16(+)-lymphocytes and activated T-lymphocytes, as well as to the reduced index of immune regulation, decreased content ofCD3-16/56+(NK)-cells (%) and the total IgE and to a greater deficiency of B-lymphocytes. Distinctions in the groups of liquidators who participated in LCF in 1986 and 1987 have been revealed. The greatest deviations in the IS indicators were found in liquidators-87. A similar effect came to light in case of a continuance in the ChNPP zones in 1986 and 1987; however, the degree of deviation of the content of CD4(+)-T-lymphocytes (41), CD8(+)-T-lymphocytes (1) and the immune regulation index (41) were remarkably higher in liquidators-87. A continuous stay in the ChNPP zones in 1987 led to the deficiency of CD4(+)-T-lymphocytes, increased values of CD8(+)-T-lymphocytes, a decreased index of CD4+/CD8+, as well as to the change in the ratio between NK-T and NK cells, increased numbers of CD95+, HLA-DR+ and activated T-lymphocytes, and a lower level of the total IgE. Long-term participation in LCF didn't cause any enhanced expression of cellular activation markers in liquidators-86. Specific features of changes in IS depending on a dose of external gamma-irradiation have been established. Increase in the frequency of MN among liquidators, in relation to the number of examinees in each age group, with age has been revealed. Distinctions in the age dynamics of IS in liquidators in the presence and in the absence of MN manifested themselves in a stable level of values of CD3+, CD4+, CD8(+)-T-lymphocytes, immune regulation index, CD95+, serum IgA at the age between 40 and 70 years old with a subsequent reduction in indicators and increase in the content of CD8(+)-T-lymphocytes with age in the absence of MN; continuous increase of CD3-16/56(+)-NK-cells in the presence of MN and decrease in the values after 70 in the absence of MN. Also revealed in IS of the both age groups of liquidators over 70 with and without MN was the deficiency of the T-cell component (CD3+, CD4(+)-T-lymphocytes, CD4+/CD8+ index) and the increase in absolute values of CD8(+)-T-lymphocytes. The growing deficiency of CD4(+)-T-lymphocytes during monitoring against the background of ever rising values of CD8(+)-T-lymphocytes leading to the weakening of the immune regulation due to progressing disorders of the T-lymphocyte regulatory subpopulation distribution can serve an indicator for the adverse prognosis of the life expectancy in the presence of MN.     

Sensitivity of soil bacteria isolated from the alienated zone around the Chernobyl Nuclear Power Plant to various stress factors

Seventy strains of chemoorganotrophic bacteria isolated by our group in 1993-1994 from soil sampled in the zone around the Chernobyl Nuclear Power Plant (ChNPP) were studied with respect to their sensitivity to various stress factors damaging DNA. Bacillus subtilis, B. cereus (both spores and vegetative cells), Methylobacterium extorquens, M. mesophilicum, and unidentified pigmented bacteria were found to be the most resistant to ultraviolet (UV) radiation, exhibiting LD90 values of 40 to more than 211 J/m2. The same bacteria, as well as Bacillus polymyxa, were tolerant to hydrogen peroxide (lethal concentrations of H2O2 ranged from 0.3 to 1.0 M); i.e., UV-resistant strains were also tolerant to hydrogen peroxide and vice versa. Fluorescent pseudomonads were the most sensitive to both UV radiation and H2O2, showing LD90 from 6 to 18 J/m2 and a lethal concentration of H2O2 lower than 0.1 M. All of the soil samples collected in the alienated zone around the ChNPP, where the radioactivity of the soil had decreased from 1000 to 2 microCi/kg soil over the period from 1987 to 1995, contained not only resistant bacteria but also a small number of bacteria sensitive to UV radiation and H2O2.     

The concentration and distribution of 137Cs in soils of forest and agricultural ecosystems of Tula Region

The paper deals with a comparative study of 137Cs contamination in forest, old arable and cultivated soils of Tula Region. Initial interception of Chernobyl derived 137Cs is higher in forest ecosystems: oak-forest > birch-forest > pine-forest > agricultural ecosystems. Vertical migration of 137Cs in deeper layers of soils was intensive in agricultural ecosystems: cultivated soils > old arable soils > birch-forest soils > oak-forest soils > pine-forest soils. In study have been evaluated spatial variability of 137Cs in soil and asymmetrical distribution, that is a skew to the right. Spatial heterogeneity of 137Cs in agricultural soils is much lower than in forest soils. For cultivated soil are determined the rate of resuspension, which equal to 6.1 x 10(-4) day(-1). For forest soils are described the 137Cs concentration in litter of different ecosystems. The role of main accumulation and barrier of 137Cs retain higher layers of soils (horizon A1(A1E) in forest, horizon Ap in agricultural ecosystems) in long-term forecast after Chernobyl accident.     

The epidemiological analysis of monitoring of the immune status in liquidators of consequences of the Chernobyl accident for early identification of risk groups and diagnostics of oncological diseases. Report 1

Ionizing radiation is one of major factors of risk of oncological diseases. A question about the frequency of malignant neoplasms (MN) and their early identification in the liquidators of consequences of the Chernobyl accident remains opened. In the present work, the results of long-term immunological monitoring of the liquidators of consequences of the failure at the Chernobyl Nuclear Power Plant (ChN PP) living in the Northwest region of Russia are analyzed; we also heve made an attempt to reveal the predictors of oncological diseases in this group of individuals. The frequency of the newly revealed MN cases in a cohort of the persons who took part in liquidation of consequences of the ChNPP failure and were followed-up in 1999-2009, has made up 89 cases per 1005 persons (8.856%), which somewhat exceeds general population indicators. Regarding the frequency of separate MN localizations, lung cancer, cancer of stomach and cancer of prostate gland predominated, which corresponds to the world's tendency of MN prevalence. It has been established that as early as 1-3 years before diagnosis of MN is confirmed in liquidators, a number of changes in the immune status comes to light: drop in percentage of CD3+ and CD4(+)-T-lymphocytes, B-lymphocytes to a lesser extent, decrease in the CD4+/CD8+ index, increase of the relative and absolute content of CD16(+)-lymphocytes, increase of absolute content of CD8(+)-T-lymphocytes, prevalence of CD3+16/56+(NK-T) cell over CD3-16/56+(NK) cells, rise of the activity of phagocytes. Patients with the presence of one or several of the above-mentioned signs should be attributed to the MN risk group for determination of tumor markers, thorough examination and dynamic observation.     

Imitation model of 90Sr behaviour in the soil and stand of pine forest

The algorithm of display of 90Sr behaviour mechanisms in forest ecosystems by method of imitating modeling is developed. Distinctive features of algorithm: the 90Sr contents in vegetation is subdivided into two parts (outside and internal pollution), which dynamics is considered separately; dynamics of a radionuclide is considered in connection with dynamics of organic substance; it is supposed, that 90Sr behaviour in plants is similar to Ca behaviour; the biological availability 90Sr contained in a soil, is integrated function of time and physico-chemical properties of the given soil. On the basis of offered algorithm the model is constructed which is used for realization of a number of numerical experiments, including reconstruction of a situation of pollution of forest ecosystem on grey forest soils in result of Kyshtym accident. The quantitative estimations of intensity of 90Sr redistribution between stand components and soil are received. The modern problems of creation of prognostication models of 90Sr dynamics in the forest ecosystems are discussed.     

Cytogenetic characteristics of seed progeny of common oak trees (Quercus robur L.) exposed to the irradiation after the accident at the Chernobyl Nuclear Power Station and growing at the territories with different levels of anthropogenic contamination

The examination of cytogenetic characteristics (the mitotic activity, the time of passing of the mitotic stages by cells, the level and the spectrum of mitosis disturbances, the nucleoli characteristics) of seed progeny of common oak trees, exposed to the radiation exposure after the accident at the Chernobyl Nuclear Power Station and growing at the territories with different levels of anthropogenic contamination was held. In spite of the normalization of the radioactive level at the examined territories the changes of the cytogenetic characteristics of common oak seed progeny in comparison with the control were noticed. Obtained results are explained from the position of the radiation induced genomic instable and of the wave kinetic of the mutation process. The questions of the advisability and of the validity of using of the seed progeny of the common oak trees, exposed to the radiation exposure, in forest restoration measures are discussed.     

The cytogenetic effect in a group of settlers from a 30-kilometer area of right of way

One of the critical human group of potential risk is the group of population from 30-km zone around the Chernobyl nuclear power plant. The cytogenetical examination of 12 persons (8 man, 4 woman, 30-60 years old) from 5 villages situated in north-west and south-east directions from the ChNPP in the frame of this zone was conducted. The data of the conventional analysis showed relatively low cytogenetic effects comparable with the effects in exposed people out of the zone (the mean level of unstable cytogenetic markers in different villages was 0.21-0.35 per 100 cells). The level of stable translocations in one case (woman, 59 years old) determined using FISH (16.62 per 100 cells for the whole genome) exceeded their spontaneous aged frequency and confirmed the high sensitivity of this method for the evaluation of real radiation exposure.     

Characteristics of morphogenesis and growth processes of conifers in the Chernobyl nuclear accident zone

In the article we present data on the study of morphogenesis and of growth processes of Scotch pine (Pinus sylvestris L.) and of Norwey spruce (Picea abies (L.) Karst.) vegetative organs after radiation exposure in the Chernobyl nuclear accident zone. The anomalies in morphogenesis processes at different absorbed doses are described in detail. It is established that the death of pine forest began under absorbed dose 80-100 Gy and more, mass yellowing of needles at 50-60 Gy, and maximal morphosis at 8-12 Gy. Inhibition phenomenon of growth processes under acute irradiation and giantism under durable chronic irradiation were also put under investigation. Features of radiation exposure on pine and fir growth processes at different ontogeny phases were characterized. High radio-sensitivity of Norwey spruce is established.