The effects of non-human species irradiation after the Chernobyl nuclear accident

Data are presented on the effects of irradiation of different biota species after the Chernobyl accident.     

Response of the glutathione system to chronic irradiation of human population after the Chernobyl accident

A complex relationship between glutathione level in plasma in human population (children living in radionuclide-contaminated regions and the Chernobyl liquidators) exposed to chronic low-level radiation after the Chernobyl accident was demonstrated. The obtained experimental data indicate different responses of the human glutathione system to low (from 0.1 to 20 cSv) and high (from 20 to 150 cSv) doses of ionizing radiation.Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 1, 2005, pp. 9–17.Original Russian Text Copyright © 2005 by Ivanenko, Burlakova.     

Infant leukemia in Belarus after the Chernobyl accident

Petridou et al. [1] have reported an increase in infant leukemia in Greek children born between 1/7/86 and 31/12/87 and have linked this increase to in utero radiation exposure due to the Chernobyl accident. Subsequently, Michaelis et al. [2] have reported a similar trend for Germany but found that it was not correlated to the levels of contamination. For Belarus, which was much more severely affected, a similar but much weaker trend is found. Received: 2 January 1998 / Accepted in revised form: 23 January 1998     

The effect of Chernobyl accident on the development of malignant diseases--situation after 20 years

The accident that occurred at the Chernobyl Nuclear Power Plant in 1986, released large quantities of radionuclides--among them radioiodine--into the atmosphere, thereby raising public concerns about its influence on thyroid structure and function, especially the development of malignancy. There were even reports about 700 deaths due to thyroid carcinoma in Russian Federation, Ukraine and Belarus, resulting from the accident. In this review we discussed the incidence of thyroid cancer in different parts of the world, especially in heavily contaminated countries, as Ukraine and Belarus, and the possible link between radioisotope activity in the thyroid and the development of malignancy. The study carried out in Minsk showed 40-fold increase of the incidence of thyroid cancer in the years 1986-1994, in comparison to the period 1977-1985. An increase of the incidence of thyroid cancer has generally been observed in many countries after the Chernobyl accident. We focused on the factors that may have an influence on this phenomenon, especially diagnostic tests, health care, social and environmental factors, like iodine level in water and soil. The results of molecular biology studies, e.g. RET translocation in carcinoma type RET/PTC1 in elderly and RET/PTC3 in children, and expression Ax1 and Gas6 in children were reviewed as well. We also mentioned other thyroid diseases, like nodular goitre, cysts, the disturbance of thyroid function and autoimmunity, possibly linked to the radiation after Chernobyl accident. Data obtained from the regions near Chernobyl showed no increased risk of other types of malignancy (leukaemia, Hodgkin's and non Hodgkin's lymphoma) in 1986-1996. In this article the epidemiology of thyroid diseases in Poland was also reviewed.     

Peculiarities of human lung prenatal morphogenesis at the first trimester of pregnancy in different periods after Chernobyl accident

The comparative histological and morphometric analysis of the bronchial structures of human fetal lungs was performed. Fetal lungs were taken from pregnant women living in radionuclide polluted zones (Novozibcov, Bryansk region) or in control regions (Moscow) in different periods after Chernobyl accident. Relative areas of the bronchial epithelial tubes and mesenchyme, quantity of bronchial branches and buds (end sections) of epithelial tubes on cut area unit were determined. The dates received in 1992-1993 showed the delay of fetal bronchial growth and branching in comparison with control. It can be estimated as tissue dysplasia of lungs from fetuses of mothers living in Novozibcov. The material received in 1995 showed the more intensive growth of bronchial branches in human fetal lungs than the material from Novozibcov and of the Moscow control, taken in 1992-1993. These date suggest the heterogenous character of lung prenatal morphogenesis reactions of offspring from pregnant women lived in different periods on controllable territories of Bryansk region.     

The effect of low doses of radiation on the glutathione status in children and adults after the Chernobyl Atomic Electric Power Station accident

A level of glutathione in the blood plasma of human population exposed to low-dose radiation after the Chernobyl accident was studied; a complicated character of dose dependence was shown. The response of the glutathione system to low and high radiation doses is different in the children living in the radionuclide-contaminated areas and in the participants of the elimination works.     

Autoimmune disorders in liqvidators 11 years after the Chernobyl accident

We studied long-lasting consequences of the low-doses irradiation on the immune system of 71 clean-up workers who participated in the emergency work after the Chernobyl Plant accident in 1986 and 25 healthy donors from Belarus. In sera of the workers the level of autoantibodies to thyroid gland antigens (thyroglobulin and microsomal fraction of thyroid gland) was increased in 48% of cases, the level of autoantibodies to lens oculis antigen was increased in 44% of cases; the level of circulating immune complexes was elevated in 55%, and the serum level of thyroglobulin in 60% of people. Immunological disorders were found without any definite clinical evidences of diseases and this allows us to consider the examined contingent as a group of risk for the development of autoimmune pathology in the future.     

Childhood leukemia in Belarus before and after the Chernobyl accident

Childhood leukemia (ICD 204–208 [1]) incidence rates in the different regions of Belarus are reported for a period before and after the Chernobyl accident (1982–1994). There are, at this point, no recognizable trends towards higher rates.     

The assessment of accumulated internal irradiation doses of the inhabitants of the populated areas in Republik Belarus after Chernobyl accident

A new system of evaluation methods has been developed for the assessment of the accumulated internal irradiation doses in the inhabitants of the populated areas of the Republic of Belarus that were contaminated by the Chernobyl radionuclides. The system is based on the results of WBC measurements. The model is based on the WBC-results of the State Dosimetric Register for the period of 1987-2010. The dose assessment model is based on the classification of the populated areas, on the regional features of the soils through which 137Cs can enter into the locally grown and produced foods. The model is also based on building the regressive correlations of accumulated internal doses to the contamination density of the territory of a populated area. Such regressive correlations are made for each region. The influence of indirect factors of dose forming was taken into consideration in the dose assessment. Among these factors are the population of the area, and the amount of forested territory around it, which were taken as correction coefficients. The coefficients were determined from the regressive correlation of the correction coefficients to a specific area of forest for each region. So called "countermeasure factor" was used for specification of other model results.     

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.     

Mini-and microsatellite mutations in children from Chernobyl accident cleanup workers

Knowledge about possible genotoxic effects of low-dose radiation on the human germline is limited and relies primarily on extrapolations from high-dose exposures. To test whether ionizing radiation can cause paternal genetic mutations that are transmitted to offspring, we enrolled families of 88 Chernobyl cleanup workers exposed to ionizing radiation. We analyzed DNA isolated from lymphocytes for mutations via DNA blotting with the multi-locus minisatellite probes 33.6 and 33.15 and via PCR in a panel of six tetranucleotide repeats. Children conceived before and children conceived after their father's exposure showed no statistically significant differences in mutation frequencies. We saw an increase in germline microsatellite mutations after radiation exposure that was not statistically significant. We found no dependence of mutation rate on increasing exposure. A novel finding was that the tetranucleotide marker D7S1482 demonstrated germline hypermutability. In conclusion, our results do not support an increased level of germline minisatellite mutations but suggest a modest increase in germline mutations in tetranucleotide repeats. Small sample size, however, limited statistical power.     

Chromosome instability revealed in children of fathers irradiated during Chernobyl accident

Four children groups with and without thyroid pathology born to fathers exposed to ionizing irradiation in 1986 during Chernobyl accident as liquidators as well as residents of territory with radioactive contamination have been cytogenetically observed. The frequency and spectrum of chromosome aberrations in peripheral blood lymphocytes have been studied using two-termed cultivation (during 48 and 144 hours). Under the short-term incubation the observed groups did not significantly differ on the mean-group integral cytogenetic parameters which corresponded to age norm, but in progeny of parents from radionuclide contaminated territory the increased level of chromosome type exchanges has been revealed. In long-termed lymphocyte cultures of children with chronic thyroiditis the significantly increased cytogenetic effects of both chromatid (single fragments) and chromosome types (abnormal monocentrics, centric rings) have been established. The data received testified the reality of the transmissible chromosome instability phenomenon in progeny of irradiated parents and confirmed the possibility of its expression in consequent mitoses.     

Chromosome alterations in cleanup workers sampled years after the Chernobyl accident

Cytogenetic analysis performed 4-13 years after the Chernobyl accident showed an elevated frequency of acentrics, chromatid exchanges, dicentrics and rings in Chernobyl cleanup workers compared to the control group. Cytogenetic data were analyzed according to the information on exposure to radiation (the year when the cleanup workers worked at the Chernobyl station, doses rates, time elapsed since exposure to radiation, and cytogenetic examination) and some lifestyle factors. The data obtained suggested that some types of chromosome aberrations could be influenced by the action of different environmental factors or lifestyle factors. The frequency of acentrics was correlated with the age of the cleanup workers, and the increased chromatid exchange frequency was attributed to smoking. The numbers of dicentrics and rings suggested a genotoxic effect of ionizing radiation that is still present over 13 years after the exposure.     

Delayed medical consequences of the Chernobyl accident in Armenia. Assessment of life quality and accelerated biological aging of accident liquidators

In this paper, some final results of 25-year investigations carried out in Scientific Centre for Radiation Medicine and Burns MH RA (SCRMB) on the Armenian cohort of the Chernobyl accident consequences liquidators are shown. These results show that health conditions of the liquidators became worse during the whole observation period. A considerable development of both pathological states atypical of radiation damages and diseases, which may be considered as radiation-induced ones, was determined. Rise of the sickness rate of almost all organism systems, first of all, nervous, cardiovascular, respiratory and digestive ones, was observed. In 70% of liquidators the main disease was primarily detected after working on CNPP. In the intervening years, the average number of diagnoses per 1 liquidator increased from 1.5 in 1987 to 7-8 in the recent time. In addition to the detected diseases, particular functional shifts in neuropsychological and vegetative status of the liquidators were observed. The overwhelming majority of them have increased tonicity of the sympathetic vegetative nervous system, asthenic and depressive syndromes occurring in the form of weakness, somnolence, mood instability, mental capacity decrease, and memory defects. In the paper, the results of investigations aimed at clarification of changes in biological aging processes of the liquidators and assessment of their "life quality" features in terms of physical, psychical and social welfare are considered. Biological aged-related passportization in a definite part of liquidators elucidated an accelerated aging rate. The studies were performed with the help of SF-36 inquirer and indicated that health status aggravation of the liquidators also affected their life satisfaction. The "life quality" indices of the liquidators significantly concede the overall average standards by both physical health and psychical and social welfare scales.     

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.     

Screening effects in risk studies of thyroid cancer after the Chernobyl accident

In this article scenarios have been developed, which simulate screening effects in ecological and cohort studies of thyroid cancer incidence among Ukrainians, whose thyroids have been exposed to ¹³¹I in the aftermath of the Chernobyl accident. If possible, the scenarios were based on directly observed data, such as the population size, dose distributions and thyroid cancer cases. Two scenarios were considered where the screening effect on baseline cases is either equal to or larger than that of radiation-related thyroid cancer cases. For ecological studies in settlements with more than ten measurements of the ¹³¹I activity in the human thyroid in May–June 1986, the screening bias appeared small (<19%) for all risk quantities. In the cohort studies, the excess absolute risk per dose was larger by a factor of 4 than in the general population. For an equal screening effect on baseline and radiation-related cancer (Scenario 1) the excess relative risk was about the same as in the general population. However, a differential screening effect (Scenario 2) produced a risk smaller by a factor of 2.5. A comparison with first results of the Ukrainian–US-American cohort study did not give any indication that a differential screening effect has a marked influence on the risk estimates. The differences in the risk estimates from ecological studies and cohort studies were explained by the different screening patterns in the general population and in the much smaller cohort. The present investigations are characterized by dose estimates for many settlements which are very weakly correlated with screening, the confounding variable. The results show that under these conditions ecological studies may provide risk estimates with an acceptable bias.     

Perinatal mortality in Bavaria, Germany, after the Chernobyl reactor accident

As has been shown by the authors of a paper recently published in this journal, a deviation from a long-term trend in perinatal mortality within the former Federal Republic of Germany occurred in 1987, i.e. 1 year following the Chernobyl disaster. It is the aim of this study to make a comparison between the areas of the state Bavaria, Germany, with different fallout levels as well as between the observed and expected numbers of perinatal deaths relating to these areas. The expected numbers of perinatal deaths, defined as external standard, were derived from the remainder of the former FRG. Testing an a priori formulated hypothesis revealed no differences in the temporal development of perinatal mortality between the areas with different fallout levels and subsequent exposures. Including May 1986 into the analysis revealed a significant increase during the first 3 months after the accident, which is due to an excess in May alone. Since no elevated radiation risks for the last days in utero are known, the additional Chernobyl radiation exposure is not plausible as a causative agent. Further analyses on stillbirths showed an increase in Southern Bavaria during the first 2 years following the accident. Later on, the rates were comparable to the expected values again. Received: 23 January 1997 / Accepted in revised form: 4 April 1997     

Chromosome aberration frequency in children with chronic thyroiditis born before and after the accident at the Chernobyl nuclear reactor

Children with chronic thyroiditis born before and after Chernobyl accident have been investigated cytogenetically using G-banding staining. It was shown that the chromosome instability and sensitivity to cesium radioisotopes increased and the pathological process in a thyroid gland implemented in persons exposed to 131I in their childhood and living in iodine-deficient territories.     

Thyroid dose reconstruction for the population of Belarus after the Chernobyl accident

An ¹³¹I environmental transfer model – adapted for Belorussian conditions – was applied to estimate thyroid doses for different population groups. For this purpose the available data were analysed and the important radioecological parameters assessed, i.e. (a) the elimination rate of ¹³¹I from grass due to weathering and growth dilution, (b) the initial interception of ¹³¹I by vegetation, (c) the transfer coefficient for ¹³¹I from grass to cow's milk, (d) the yield of pasture grass and (e) the milk consumption rate. Additionally, the influence of applied countermeasures has been taken into account, such as the interruption of locally produced milk consumption, and the appropriate correction factors have been estimated. As a result, the average age-dependent thyroid doses were assessed for the Belorussian population. The highest average doses in children (> 1 Gy) have been estimated for the Bragin, Khoiniki, Narovlia and Vetka raions of the Gomel oblast. The thyroid exposure tends to decrease from the southeastern (closest to the Chernobyl nuclear power plant areas) to the northwestern part of the republic. When comparing the assessed thyroid doses with dose estimates derived from direct ¹³¹I activity measurements in thyroids (for the locations with more than 15 direct measurements), the results agree fairly well. The model calculation may perhaps overestimate thyroid doses of the population residing in the settlements of the central and northern parts of Belarus, distant from the areas with direct measurements of ¹³¹I activities in soil, grass and milk. These thyroid dose estimates may serve as a basis for further epidemiological studies and risk analyses.