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.     

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.     

Provision of residents of the city of Kiev with vitamins C and B1. Effectiveness of a complex vitamin-mineral preparation in preventing spring vitamin deficiencies

The investigation was conducted on provision with vitamins C and B1 of Kyiv inhabitants limited contingent at spring period and efficiency of complex vitamin-mineral preparations in normalisation of the vitamins level in blood of human-subjects. The deficit of vitamin C in 54% and vitamin B1 in 18.5% of the investigated people was revealed. Supradin gave the best results among rest preparations ("Centrum", "Vitrum", "Duovit", "Multi-Tabs") in the normalization of the level of vitamin C and biologically-active form of thiamine (thiamindiphosphate) in the blood of investigated people.     

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,...     

Selenium status of pregnant women and newborns in the former Soviet Union

The estimation of the selenium status during pregnancy is of great importance because of the significance of selenium for fetus growth and antioxidant protection of neonates. This problem is especially urgent for Russia and its neighbors because very little data are available and because data on soil selenium predict low intake levels of selenium. A large epidemiological investigation made in various areas of the former USSR allowed us to obtain the first information concerning the subject. Serum samples were obtained during 1990–1998 from 556 female blood donors aged 20–53 yr and 722 pregnant women (18–33 yr) during different times of gestation. The mean serum selenium concentration of nonpregnant women varied from 0.87 μmol/L (Slavutich, Ukraine) to 1.74 μmol/L (Ioshkar-Ola, Mary-El) and that of women at delivery from 0.66 μmol/L (Zaporozie, Ukraine) to 1.34 μmol/L (Sakhalin, Russia). Compilation of literature and present data on serum selenium showed the following relationships: nonpregnant women versus women at delivery, y=x -0.25, r=0.94; women at delivery versus umbilical serum, log y=log x -0.2, r=0.97. The two relationships were used to predict serum selenium values for pregnant women taking into account the progressive serum selenium decrease during advancing pregnancy. In almost half of the towns (i.e. 22–50%), pregnant women were considered to have relative selenium deficiency.     

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.     

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 effect of Chernobyl accident on the development of non malignant diseases

The early medical complications of Chernobyl accident include post radiation disease, which were diagnosed in 134 subjects affected by ionizing radiation. 28 persons died during the first 100 days after the event. The increase occurrence of coronary heart disease, endocrine, haematological, dermatological and other diseases were observed after disaster in the contaminated territories. We also discussed the impact of ionizing radiation from Chernobyl accident on pregnancy and congenital defects occurrence. Changes following the Chernobyl accident, as the inhabitants migration from contaminated regions, political and economic conversions, led to depression, anxiety, and even to "epidemic" of mental diseases. Increased suicide rate, car accidents, alcohol and drug abuse have been observed in this population. Nowadays vegetative neurosis is more often diagnosed in Ukrainian children. Epidemiological studies were conducted on the ionising radiation effect on the health and on the dose of received radiation after Chernobyl accident face numerous problems as the absence of reliable data regarding diseases in the contaminated territories.     

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.     

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.     

Selenium levels in human plasma and hair in northern poland

The aim of this study was to (1) estimate the concentration of selenium in the plasma of 146 residents (65 men and 81 women) and in the hair of 34 persons from the Gdańsk region in northern Poland, aged 19–70 and (2) compare the obtained results with data corresponding to healthy populations living in different European countries. Selenium in plasma was determined by atomic absorption spectrometry using the hydride generation method. The mean selenium concentration in plasma of the investigated persons was 73.3 ± 14.1 μg/L, 76.7 ± 13.2 μg/L in men, and 70.4 ± 14.7 μg/L in women. No age — dependent differences in plasma selenium were found in the investigated population. In 20% of the investigated persons, the selenium level in plasma was lower than 60 μg/L. The mean selenium concentration in hair was 0.30 ± 0.11 μg/g. A positive, statistically significant correlation between selenium concentrations in the plasma and hair of the investigated persons was found. The obtained results indicate that the selenium level in significant part of this population is suboptimal and should be elevated by supplementation with this element.     

Psychophysiological and personality factors of the accident rate at power plants]

Psychophysiological and personality factors of accident rate are revealed. It is substantiated as inexpedient to professionally train and to employ in operator positions the persons with predisposition to create accident as well as necessary to allow for individual-psychophysiological peculiarities of operators while investigating the causes of accidents.     

Data from the Wroc?aw region about thyroid diseases and use of prophylactic iodine after the reactor accident in Czernobyl]

The radiological contamination of Wroc?aw Region after Czernobyl accident was evaluated as moderate. In the frame of Research Programme MZ-XVII 4310 persons (2012 men and 2298 women) were randomly selected and investigated. Among them were 1525 children up to 16 years old. 925 children and 854 adults took potassium iodide; only minority in April but majority between May 1st and May 5th. Side effects was rare phenomenon seen in about 5% of those who ingested potassium iodide and in majority of cases was very mild (with rash and vomiting as most common clinical symptoms). Only 13 persons with side effects have visited physicians. Among 955 women aged 19-40 years 71 were pregnant in May 1986. 55 of them delivered on time, 3 before time. Average health state of newborns was 9.1 according to Apgar scale. 10 women have had spontaneous abortion and 3 decided to terminate pregnancy in first 6 weeks. The physical examination revealed the presence of diffuse goiter in 384 persons and of nodular goiter in 23 persons. In majority of cases the goiter was small, OB or I. according to WHO classification.     

Genetic effects of bystander factors from the blood sera of people irradiated as the result of the Chernobyl accident

The purpose of this work was the analysis of the effects of bystander factors from blood sera of people affected by the Chernobyl accident on human keratinocyte cell culture (HPV-G cells). A new method was developed for evaluation of the bystander factor presence in vivo in blood of the people irradiated by the Chernobyl accident. Affected population groups included liquidators of the Chernobyl accident and people living and working in areas of the Gomel region contaminated by radionuclides. The analysis has shown that bystander factors persist in Chernobyl liquidator blood samples for more than 20 years since irradiation. The data suggest that blood sera contain bystander factors, which are able to induce micronuclei and decrease the metabolic activity of HPV-G cells.     

Content of free amino acids in blood plasma of the clean-up personnel at the Chernobyl nuclear power plant accident

In two groups of the persons participating in liquidation of the Chornobyl Power Plant Catastrophe (individuals which suffered from acute radiation sickness and those ones who were exposed to irradiation at doses 0.25-1.0 Gy) in a year after medical treatment the free amino acids, their derivatives, glucose, sodium lactate and pyruvate homeostasis changed in comparison with the control. The causes and possible mechanisms of these substances exchange regulation disorders in the key biochemical reactions ensuring the body organs and systems functioning were estimated. The experimental findings received can be used at planning the further examination and treatment-and-prophylactic measures for the persons which have been affected by ionizing radiation consequently the accident at the Chornobyl Nuclear Power Plant.     

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.     

Karyopathological traits of thyrocytes and exposure to radioiodines in Belarusian children and adolescents following the accident at the Chernobyl nuclear power plant

The Belarus-American (BelAm) thyroid study cohort consists of persons who were 0-18 years of age at the time of exposure to radioactive iodine fallout from the 1986 Chernobyl nuclear power plant accident and who have undergone serial thyroid screenings with referral for fine-needle aspiration biopsy (FNAB) using standardized criteria. We investigated thyrocyte nuclear abnormalities in cytological samples from FNABs in 75 BelAm subjects with single and multiple thyroid nodules and 47 nodular goiter patients from Leningrad, Russia, unexposed to Chernobyl fallout. Nuclear abnormalities examined included internuclear chromosome bridges and derivative nuclei with broken bridges (i.e., "tailed" nuclei), which are formed from dicentric and ring chromosomes and thus may be cellular markers of radiation exposure. Among subjects with single-nodular goiter, thyrocytes with bridges were present in 86.8% of the exposed BelAm cohort compared with 27.0% of unexposed controls. The average frequency of thyrocytes with bridges and with tailed nuclei was also significantly higher in the BelAm subjects than in controls. Among subjects with multinodular goiters, thyrocytes with bridges were present in 75.7% of exposed BelAm patients compared with 16.7% of unexposed controls; thyrocytes with tailed nuclei were observed in all of the BelAm subjects but in only 40% of controls, and the mean frequencies of bridges and tailed nuclei were significantly higher in the exposed group. Unusually, long bridges were detected in 29% of BelAm patients with single-nodular goiters and 35% of those with multinodular goiters, while no such abnormalities were observed among patients from the Leningrad region. In the exposed subjects from BelAm, we also found positive correlations between their estimated dose of Iodine-131 from Chernobyl fallout and the frequency of tailed nuclei (p = 0.008) and bridges (p = 0.09). Further study is needed to confirm that these phenomena represent consequences of radiation exposure in the human organism.     

The accident at Chernobyl and outcome of pregnancy in Finland.

OBJECTIVE--To evaluate the outcome of pregnancy in Finnish women after the accident at the Chernobyl nuclear power plant on 26 April 1986. DESIGN--Geographic and temporal cohort study. SETTING--Finland divided into three zones according to amount of radioactive fallout. SUBJECTS--All children who were exposed to radiation during their fetal development. Children born before any effects of the accident could be postulated--that is, between 1 January 1984 and 30 June 1986--served as controls. INTERVENTIONS--Children were divided into three temporal groups: controls, children who were expected to be born in August to December 1986, and children who were expected to be born in February to December 1987. They were also divided, separately, into three groups according to the three geographic zones. END POINT--Incidence of congenital malformations, preterm births, and perinatal deaths. MEASUREMENTS AND MAIN RESULTS--There were no significant differences in the incidence of malformations or perinatal deaths among the three temporal and three geographic groups. A significant increase in preterm births occurred among children who were exposed to radiation during the first trimester whose mothers lived in zones 2 and 3, where the external dose rate and estimated surface activity of caesium-137 were highest. CONCLUSIONS--The results suggest that the amount of radioactive fallout that Finnish people were exposed to after the accident at Chernobyl was not high enough to cause fetal damage in children born at term. The higher incidence of premature births among malformed children in the most heavily polluted areas, however, remains unexplained.     

15 years after the accident at the Chernobyl Nuclear Power Plant

Health effects as a result of the accident at the Chernobyl nuclear power plant occurred in 1986 are considered in the paper. Wrong prognosis of the health effects with respect to mortality and morbidity among the population exposed to low radiation doses is shown. Proven increase in thyroid cancer cases among people who were children aged from 0 to 18 at the time of the accident is shown. Linear relationship between thyroid cancer cases and dose to thyroid ranged from 0.2 to 4.0 Gy is considered. An additional absolute risk of thyroid cancer in children varies in the range 1.9-2.6 cases per 10(4) person-year Gy. During the fifteen years following the accident no cases of acute and chronic radiation sickness have been revealed because the population living in contaminated areas received low radiation doses. Also, exposures to low radiation doses did not result in excess of malignant tumors among population. In some cases the outcomes of acute radiation sickness were as follows: radiation damages to the skin, cancer cataracts, development of oncopathology.     

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.