Dynamics of the cytogenetic effect in re-examined individuals who have participated in eliminating the emergency at the Chernobyl Atomic Power Plant in various periods after irradiation]

The repeat cytogenetic examination of 22 persons who were exposed to acute radiation while eliminating emergency at the Chernobyl Atomic Power Plant has revealed interindividual variability in the rate of elimination of radiation-induced chromosome mutations. The data obtained have confirmed complexity to reconstruct individual radiation doses by the results of cytogenetic analysis carried out 1-3 years after the ionizing radiation effect.     

Genetics of cattails in radioactively contaminated areas around Chornobyl

Research on populations from radioactively contaminated areas around Chornobyl has produced ambiguous results for the presence of radiation effects. More studies are needed to provide information on whether radiation exposure at Chornobyl significantly affected genetic diversity in natural populations of various taxa. Eleven and nine variable microsatellite loci were used to test for differences in genetic diversity between reference and Chornobyl populations of two cattail species (Typha angustifolia and Typha latifolia, respectively) from Ukraine. Our purpose was to determine whether radiation had a significant impact on genetic diversities of the Chornobyl Typha populations, or if their genetic composition might be better explained by species demography and/or changes in population dynamics, mainly in sexual and asexual reproduction. Populations closest to the reactor had increased genetic diversities and high number of genets, which likely were due to factors other than radiation including increased gene flow among Chornobyl populations, enhanced sexual reproduction within populations, and/or origin of the genets from seed bank. Both Typha species also demonstrated small but significant effects associated with latitude, geographical regions, and watersheds. Typha's demography in Ukraine possibly varies with these three factors, and the small difference between Chornobyl and reference populations of T. latifolia detected after partitioning the total genetic variance between them is probably due primarily to these factors. However, the positive correlations of several genetic characteristics with radionuclide concentrations suggest that radiation may have also affected genetics of Chornobyl Typha populations but much less than was expected considering massive contamination of the Chornobyl area.     

The intestinal microflora of persons subjected to a radiation lesion]

The content of large intestine has been studied in persons exposed to radiation injury in consequence of the accident at the Chernobyl Atomic Power Plant. It is stated that bifidobacteria (10(7)-10(10) cells in 1 g of feces) prevailed (as in healthy people), Bifidobacterium indicum being a dominating species. Amount of lactic-acid bacteria in 1 g of defecations of examined patients was within the range of 10(6)-10(9) cells and in certain persons it reached 10(10) cells (primarily fecal Enterococci). A considerable amount of patients with acute radiation sickness of the 3d degree had in their intestine 10(9)/g of lactic-acid bacteria, Lactobacillus casei and L. plantarum prevailing there. The frequency of yeast isolation from defecations of patients constituted 83%, while the number of cells in 1 g of feces--from 10 to 10(4). Yeast of the Candida genus, mainly Candida parapsilosis, prevailed. The species composition of isolated microorganisms has no substantial differences from microcenosis of healthy people. The content of intestine of persons suffered from radiation is characterized only by greater amount of lactic-acid bacteria and enterococci as compared with healthy adults.     

Post-Chernobyl thyroid cancers in Ukraine. Report 2: risk analysis

On April 26, 1986, the worst nuclear reactor accident to date occurred at the Chornobyl (Chernobyl) power plant in Ukraine. Millions of people in Ukraine, Belarus and Russia were exposed to radioactive nuclides, especially (131)I. Since then, research has been conducted on various subgroups of the exposed population, and it has been demonstrated that the large increase in thyroid cancer is related to the (131)I exposure. However, because of study limitations, quantified risk estimates are limited, and there remains a need for additional information. We conducted an ecological study to investigate the relationship between (131)I thyroid dose and the diagnosis of thyroid cancer in three highly contaminated oblasts in Northern Ukraine. The study population is comprised of 301,907 persons who were between the ages of 1 and 18 at the time of the Chornobyl accident and were living in 1,293 rural settlements in the three study oblasts. Twenty-four percent of the study population had individual thyroid dose estimates and the other 76% had "individualized" estimates of thyroid dose based on direct thyroid measurements taken from a person of the same age and gender living in the same or nearby settlement. Cases include 232 thyroid cancers diagnosed from January 1990 through December 2001, and all were confirmed histologically. Dose-response analyses took into account differences in the rate of ultrasound examinations conducted in the three study oblasts. The estimated excess relative risk per gray was 8.0 (95% CI = 4.6-15) and the excess absolute risk per 10,000 person-year gray was estimated to be 1.5 (95% CI = 1.2-1.9). In broad terms, these estimates are compatible with results of other studies from the contaminated areas, as well as studies of external radiation exposure.     

The natural anti-Pseudomonas aeruginosa and anti-Proteus immunity of the suitable donor population]

The natural anti-pyocyanic and anti-Proteus immunity of donorable population of Kiev before the accident at Chernobyl Atomic Power Plant has been studied. Blood serums of 3024 deliberately non-immunized persons have been studied. It is determined that there are natural anti-pyocyanic and anti-Proteus antibodies in blood serum of people with different group belonging during the all periods of a year (by ABO system). The anti-pyocyanic and anti-Proteus antibodies of high titers in blood serum are found in summer most frequently.     

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.     

Bipolarization of Risk Perception about the Health Effects of Radiation in Residents after the Accident at Fukushima Nuclear Power Plant

The late health effects of low-dose rate radiation exposure are still a serious public concern in the Fukushima area even four years after the accident at Fukushima Daiichi Nuclear Power Plant (FNPP). To clarify the factors associated with residents’ risk perception of radiation exposure and consequent health effects, we conducted a survey among residents of Kawauchi village in May and June 2014, which is located within 30 km of FNPP. 85 of 285 residents (29.8%) answered that acute radiation syndrome might develop in residents after the accident, 154 (54.0%) residents responded that they had anxieties about the health effects of radiation on children, and 140 (49.1%) residents indicated that they had anxieties about the health effects of radiation on offspring. Furthermore, 107 (37.5%) residents answered that they had concerns about health effects that would appear in the general population simply by living in an environment with a 0.23 μSv per hour ambient dose for one year, 149 (52.2%) residents reported that they were reluctant to eat locally produced foods, and 164 (57.5%) residents believed that adverse health effects would occur in the general population by eating 100 Bq per kg of mushrooms every day for one year. The present study shows that a marked bipolarization of the risk perception about the health effects of radiation among residents could have a major impact on social well-being after the accident at FNPP.     

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.     

Measurements of gamma (γ)-emitting radionuclides with a high-purity germanium detector: the methods and reliability of our environmental assessments on the Fukushima 1 Nuclear Power Plant accident

The severe accident of Fukushima 1 Nuclear Power Plant due to the Tohoku Region Pacific Coast Earthquake in 11 March 2011 caused wide contamination and pollution by radionuclides in Fukushima and surrounding prefectures. In the current JPR symposium, a group of plant scientists attempted to examine the impact of the radioactive contamination on wild and cultivated plants. Measurements of gamma (γ) radiation from radionuclides in “Fukushima samples”, which we called and collected from natural and agricultural areas in Fukushima prefecture were mostly done with a high-purity Ge detector in the Graduate School of Maritime Sciences, Kobe University. In this technical note, we describe the methods of sample preparation and measurements of radioactivity of the samples and discuss the reliability of our data in regards to the International Atomic Energy Agency (IAEA) Interlaboratory comparisons and proficiency test (IAEA proficiency test).     

Long-term effects of low-dose irradiation on human health.

The effects caused by low-dose irradiation differ from those caused by high-dose irradiation. At present only little is known about the long-term effects of chronical exposure of individuals and whole populations to low-dose irradiation. This problem particularly concerns people living in territories heavily contaminated with radioactive material due to Chernobyl Nuclear Power Plant accident. We investigated different parameters of the peripheral blood from 124 men, working at the "Shelter" object (demolished block IV of the nuclear power plant). In many cases the accumulated radiation dose (gamma-rays) was more than 50 rem. As control group we examinated 302 male donors (of the same age) from the Kiev blood-transfusion station. The studies revealed the following effects in the "Shelter" object workers: an increased manifestation of signs of common-inflammatory reactions, such as an increased number of leukocytes and absolute number of white blood cells, an unproportionally high number of monocytes and band neutrophiles, and an increase in plasma cytokine levels (interferon-alpha, tumor necrosis factor-beta but not interleukin-1beta). Ongoing studies are targeted to develop and introduce new methods and techniques to measure the frequency of DNA strand breaks in peripheral blood lymphocytes for the surveillance of persons working and/or living in a radioactively contaminated environment after Chemobyl accident.     

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.     

Multiaberrant cell formation caused by exposure to internal densely-ionizing irradiation

The origin of multiaberrant cells (MACs) was studied by comparing the structure and intensity of chromosome damage in peripheral blood lymphocytes of two groups of people: workers of Siberian Chemical Plant differing in the content of plutonium-239 in their bodies, and inhabitants of a non-polluted settlement (control group). Plutonium-239 is known to be a long-lived densely-ionizing source of alpha-radiation with high linear energy delivery; therefore, it has a stronger effect on cell hereditary structures than gamma-rays. In persons with the content of plutonium-239 higher than 13 nCu, the frequency of MAC was 0.105% which at least tenfold exceeds the spontaneous level. The chromosome-type aberrations that are usually induced by ionizing radiation predominated in MACs. Our results suggest that MAC formation may be caused by internal body irradiation with the incorporated sources of densely-ionizing radiation.     

A cohort study of thyroid cancer and other thyroid diseases after the Chornobyl accident: objectives, design and methods

The thyroid gland in children is one of the organs that is most sensitive to external exposure to X and gamma rays. However, data on the risk of thyroid cancer in children after exposure to radioactive iodines are sparse. The Chornobyl accident in Ukraine in 1986 led to the exposure of large populations to radioactive iodines, particularly (131)I. This paper describes an ongoing cohort study being conducted in Belarus and Ukraine that includes 25,161 subjects under the age of 18 years in 1986 who are being screened for thyroid diseases every 2 years. Individual thyroid doses are being estimated for all study subjects based on measurement of the radioactivity of the thyroid gland made in 1986 together with a radioecological model and interview data. Approximately 100 histologically confirmed thyroid cancers were detected as a consequence of the first round of screening. The data will enable fitting appropriate dose-response models, which are important in both radiation epidemiology and public health for prediction of risks from exposure to radioactive iodines from medical sources and any future nuclear accidents. Plans are to continue to follow-up the cohort for at least three screening cycles, which will lead to more precise estimates of risk.     

Ultraviolet irradiation of soil samples as a model of the effect of stress factors on bacterial diversity in soil ecosystem

UV irradiation is proposed for use in studying the effect of radioactive irradiation, since radioresistant bacteria are, as a rule, resistant to UV, and the mechanisms of repair of cell damage induced by UV and ionizing radiation are similar. It was found that the total number of bacteria and the number of dominant species in soil samples exposed to UV radiation decreased, indicating the unfavorable effect of UV radiation on bacterial diversity in soil ecosystems. The percentage of cells of bacteria belonging to dominant species varied significantly depending on the intensity of UV irradiation. It can be inferred that long-term irradiation of soils must impair the stability of soil ecosystems, a phenomenon that was indeed observed in the zone around the Chernobyl Nuclear Power Plant. At the same time, the UV irradiation of soil samples made it possible to reveal minor species, primarily UV-resistant pigmented bacteria. UV irradiation can probably be used as a selective factor for the isolation of radioresistant species.     

The effect of gamma-radiation and desiccation on the viability of the soil bacteria isolated from the alienated zone around the Chernobyl Nuclear Power Plant

Methylobacterium extorquens, M. mesophilicum, and Bacillus subtilis strains were found to be resistant to gamma-radiation, irrespective of whether they were isolated from the alienated zone around the Chernobyl Nuclear Power Plant or outside this zone. The LD90 of Methylobacterium and B. subtilis strains with respect to gamma-radiation was 2.0-3.4 and 3.7-4.4 kGy, respectively, whereas their LD99.99 values were 4.5-6.9 and more than 10 kGy, respectively. The high threshold levels of gamma-radiation for Methylobacterium and B. subtilis imply the efficient functioning of DNA repair systems in these bacteria. Unlike Bacillus polymyxa cells, the cells of M. extorquens, M. mesophilicum, and B. subtilis were also resistant to desiccation. Pseudomonas sp., Nocardia sp., and nocardioform actinomycetes were sensitive to both gamma-radiation and desiccation. Similar results were obtained when the bacteria studied were exposed to hydrogen peroxide and ultraviolet radiation. The results obtained indicate that the bacteria that are resistant to gamma-radiation are also resistant to desiccation, UV radiation, and hydrogen peroxide. The possibility of using simple laboratory tests (such as the determination of bacterial resistance to UV light and desiccation) for the evaluation of bacterial resistance to gamma-radiation is discussed.     

Cluster analysis of non-insect macro-invertebrates of the upper potomac river

Summary A series of limnological surveys carried out from 1956 until 1965 were made in the vicinity of the Dickerson Plant of the Potomac Electric Power Company by the Limnology Department of the Academy of Natural Sciences of Philadelphia. These surveys were made at various stages of growth of the power station and at high and low water levels of the river. Cluster analyses were made of the non-insect macro-invertebrates in order to provide a rapid and explicit means of analyzing the data, particularly relationships among aggregations of species. On the basis of the cluster analysis of data on occurrence and distribution of non-insect macro-invertebrates, no changes in the environment of the Upper Potomac River can be ascribed to the operation of the Dickerson Plant of the Potomac Electric Power Company. This conclusion agrees with the other results obtained by analyses of protozoan, algal, fish, and insect species. Jaccard coefficients among aggregates of the invertebrates included in this study are generally higher than those for the other groups of organisms studied except for fish. This may be the result of high tolerance of some of the species to a wide range of environmental conditions.     

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.     

Chernobyl clean-up workers erythrocyte membrane lipid content at the remote period

Chernobyl Nuclear Power Plant accident clean-up workers were exposed to different radiation doses. Realization of remote effects depends on cellular membrane structure and function. We studied lipid composition of erythrocyte ghost and blood plasma in clean-up workers on the 12-th year after the accident. Groups of Chernobyl accident clean-up workers, non-irradiated patients with the same diseases and healthy controls were studied. Phospholipids were analyzed by two dimentional thin layer chromatography on silica gel. To analyse fatty acids and cholesterol gas chromatography was used. Total cholesterol and total phospholipids amounts in clean-up workers erythrocyte ghost were increased. The level of sphingomyelin and phosphatidylethanolamine raised. In some of the studied irradiated patients lysophosphatidylethanolamine appeared. The distribution of (diacyl)- and plasmalogen forms of phosphatidylcholine and phosphatidylethanolamine was not affected. The fatty acid composition changed slightly except 22:5 n-3, which level significantly increased and 22:5 n-6, which quantity lowered. The unsaturation index remains unchanged. No change in lipid composition of blood plasma was detected. All the changes in lipid composition of erythrocyte ghost of irradiated and unexposed patients were very similar. The obtained results confirm the suggestion about non-specific remote effects after exposure to low doses of ionizing irradiation.     

Mortality among the liquidators of the Chernobyl accident: dose dependences and groups of the potential risk

Dynamics of the mortality and the mortality radiation risks among male emergency workers of 1986-1987 years of entrance to the Chernobyl zone is analyzed. The average dose of external gamma-exposure for this cohort equals 128 mGy. The size of the cohort at the beginning of the follow-up in 1992 was 47820 persons. For the follow-up period 1992-2006 statistically significant radiation risks of death rates have been estimated: for the mortality from all causes, the excess relative risk per Gy (ERR/Gy) equals 0.42 with 95% confidence interval (95% CI) (0.14-0.72); for the mortality from solid cancers ERR/Gy = 0.74, 95% CI (0.03-1.76); and for the mortality from the circulatory system diseases ERR/Gy = 1.01, 95% CI (0.51-1.57). Based on these estimates the risk groups were ranked among all Russian emergency workers (160 thousand persons): the group of the potential radiation risk with doses more than 150 mGy (33488 persons) and the group of the high radiation risk with doses more than 240 mGy (6054 persons).     

Childhood leukemia in Ukraine after the Chornobyl accident

Radiation and Environmental Biophysics - This population-based ecological study analyzes the prevalence of childhood leukemia in Ukraine before and after the Chornobyl nuclear power plant accident,...