The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 5. Longevity and the carcinogenic effects]

Remote effects in laboratory animals living in conditions of exposure to a mixture of external and internal radiation resulted from the Chernobyl A.P.S. disaster have been investigated. It has been found that the rate of deaths from non-tumor illnesses grows, the incidence of neoplasms increases and their latency time decreases. The redistribution within the spectrum of benign and malignant tumors and the increase in the multiplicity coefficient have been revealed. It is concluded that chronic exposure of animals to low-level radiation from the radionuclides, resulted from the accident, brings about a much larger number of negative stochastic and nonstochastic remote effects as compared to those expected from the extrapolation of the effects produced by high radiation doses.     

The biological effects in animals related to the accident at the Chernobyl Atomic Electric Power Station. 2. The state of bone marrow hematopoiesis in rats]

It has been shown that rats born during the first months after the Chernobyl A.P.S. disaster exhibit essential changes in the peripheral blood and bone marrow haemopoiesis throughout the entire lifetime. Rats brought up in Chernobyl from the age of three months on display even more pronounced changes. It is assumed that the changes in the haemopoiesis develop due to the continuous influence of low-level radiation of different quality and are attributed to the effect of the incorporated radionuclides.     

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.     

Complexes of soil micromycetes in the area of the influence of the Chernobyl Atomic Electric Power Station]

Complexes of soil micromycetes in the Chernobyl 30-km zone of the Ukrainian Polesye were studied for 1986-1989 with regard for such ecological parameters as the level of radiation contamination, a particular observation site, depth of soil horizon and season. As a result of the study correlation pleiads of soil micromycete complexes have been revealed with their structure and fungal genera characteristic of such complexes determined. The overwhelming majority of correlation pleiads of fungal complexes are attributed to complex-organized ones and this indicated high radioresistance of mycobiota in the studied, soils. Melanine-containing genera of fungi rank among the first in formation of correlation pleiads of soil micromycete complexes.     

Species richness and abundance of forest birds in relation to radiation at Chernobyl

The effects of low-level radiation on the abundance of animals are poorly known, as are the effects on ecosystems and their functioning. Recent conclusions from the UN Chernobyl forum and reports in the popular media concerning the effects of radiation from Chernobyl on animals have left the impression that the Chernobyl exclusion zone is a thriving ecosystem, filled with an increasing number of rare species. Surprisingly, there are no standardized censuses of common animals in relation to radiation, leaving the question about the ecological effects of radiation unresolved. We conducted standardized point counts of breeding birds at forest sites around Chernobyl differing in level of background radiation by over three orders of magnitude. Species richness, abundance and population density of breeding birds decreased with increasing level of radiation, even after controlling statistically for the effects of potentially confounding factors such as soil type, habitat and height of the vegetation. This effect was differential for birds eating soil invertebrates living in the most contaminated top soil layer. These results imply that the ecological effects of Chernobyl on animals are considerably greater than previously assumed.     

The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 10. Cooperative immune reactions in different generations of mice]

The immune status of mice has been assessed by the whole complex of data. The permanent action of low-level radiation has been shown to suppress considerably the rate of reactions of the delayed-type hypersensitivity and "graft versus host" disease, as well as NK and specific cytolytic T-lymphocyte activity. The dynamics of accumulation and the levels of antiviral antibodies in the serum, lung and trachea extracts are virtually invariable. The resistance of experimental animals to influenza is lower than that of non-irradiated mice of the same line and age. The data obtained indicate that the immune disturbances revealed are connected not only with the alteration of lymphoid cell populations, but also with the alteration of the immune regulation mechanisms.     

The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 9. The morphofunctional indices of the immunocompetent organs in mice]

The permanent action of small doses of low-intensity radiation on the immune status of 2.5-3.5 month CC57W mice has been investigated. Total doses of internal and external irradiation were about few cGy. The permanent action of low-level radiation on the experimental animals of the first and fourth generations was shown to change spleen and lymph nodes weights and the count of lymphocytes isolated from these organs. Cellularity and DNA synthesis in the lymph-node lymphocytes and their proliferative response to polyclonal mitogens also changed. The alterations in the parameters that characterized T-lymphocyte population were statistically significant.     

The biological effects in animals related to the accident at the Chernobyl Atomic Electric Power Station. 6. The physiological development and cytogenetic indices of the progeny of rats]

Certain alterations have been revealed in the postnatal ontogenesis parameters of albino mongrel rats and their descendants constantly kept within the thirty-kilometer zone of the Chernobyl A.P.S. Structural disturbances have been found in bone marrow cell chromosomes.     

The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 11. The ultrastructure of the bone marrow cells in different generations of rats]

In studying the bone marrow cell ultrastructure in male rats (F0-F2 generations) aged 3 months, which were brought up within the thirty kilometer Chernobyl A.P.S. disaster area, considerable submicroscopic changes have been revealed in the cells at all stages of maturation, including undifferentiated blasts and mature forms of cells of the neutrophilic, eosinophilic, monocytic and erythroid haemopoiesis series, as well as stromal elements of the microenvironment, megakaryocytes and endothelium. The severity of these changes increases, as the number of generations grows, displaying frequently a destructive character.     

The ultrastructural characteristics of the bronchial mucosa in chronic inflammation in participants in the cleanup of the aftermath of the accident at the Chernobyl Atomic Electric Power Station]

Bronchial biopsies from persons exposed to radiation after the Chernobyl accident with clinically verified chronic bronchitis were studied by electron microscopy. The results demonstrate transformed alterative, compensatory-adaptive and inflammatory reactions in bronchial mucosa of contingent. Nevertheless, their integral significance does not alter the nosologic form, and some structural equivalents have dynamic expression.     

The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 8. The status of cellular immunity in different generations of rats]

In studying immunity in laboratory rats of different generations (P, F1 and F2) brought up in Chernobyl in 1989-1990 the authors have revealed the development of leuko- and lymphopenia; decrease in the absolute content of immunocompetent cells bearing Fc receptors to IgG; stable and long-lasting suppression of blood NK cell activity; reduction of antibody-dependent cytotoxicity; and changed ability of blood lymphocytes to interact contactly with allogenic mast cells. The most considerable disorders have been found in 6- and 9-month-old F1 rats and in 3- and 6-month-old F2 rats.     

Reduced abundance of insects and spiders linked to radiation at Chernobyl 20 years after the accident

Effects of low-level radiation on abundance of animals are poorly known. We conducted standardized point counts and line transects of bumble-bees, butterflies, grasshoppers, dragonflies and spider webs at forest sites around Chernobyl differing in background radiation by over four orders of magnitude. Abundance of invertebrates decreased with increasing radiation, even after controlling for factors such as soil type, habitat and height of vegetation. These effects were stronger when comparing plots differing in radiation within rather than among sites, implying that the ecological effects of radiation from Chernobyl on animals are greater than previously assumed.     

The biological effects in animals related to the accident at the Chernobyl Atomic Electric Power Station. 4. The morphological and ultrastructural changes in the liver of rats]

A study was made of the morphological and ultrastructural changes in hepatic tissue of rats lived within the Chernobyl accident zone during the period of 6 to 25 months. Considerable nonspecific changes in hepatocytes (fatty, vacuolar and parenchymatous degeneration, and hepatocyte necrobiosis) were seen throughout the entire period of observation. Coagulation necrosis of certain hepatocytes, Kupffer and endothelial cells, and the development of microcholangiomas by the end of the second year were the most characteristic alterations.     

Predicting radionuclide transfer to wild animals: an application of a proposed environmental impact assessment framework to the Chernobyl exclusion zone

A number of assessment frameworks have been proposed to provide a mechanism to demonstrate protection of the environment from ionising radiation. Whilst some of these are being used for assessment purposes they have largely not been validated against field measurements. In this paper we compare the predictions of transfer parameters recommended by one of these frameworks (FASSET) with observed whole-body 90Sr and radiocaesium activity concentrations in a range of mammal and invertebrate species sampled within the Chernobyl exclusion zone. Predicted activity concentrations were generally within the observed ranges and mean predictions for reference organisms were similar to, or circa one order of magnitude higher than, the observed means. However, some predictions were more than one order of magnitude lower than observed values. No data were available to test predictions for the other radionuclides released by the Chernobyl accident. In a separate paper the outputs of this assessment will be used to estimate doses to reference organisms and compare these to observed radiation induced effects reported within the Chernobyl zone.     

The dose estimation of woody plants in the long-term after the Chernobyl NPP accident

Dosimetric models have been developed to estimate the exposure doses of woody plants growing in the area contaminated by long-lived radionuclides. The models are parameterized based on the data obtained from the experimental plots in the south-west districts of the Bryansk region affected by radioactive fallout of the Chernobyl NPP accident. Doses are estimated to generative organs of pine trees from these plots. The contribution from various sources and types of ionizing radiation to the absorbed dose formation for these objects is determined.     

Radiation reactions and the possibilities for their modification in rats exposed in the area of the Chernobyl Atomic Electric Power Station]

A study was made of some embryological, hematological, cytogenetic and biochemical characteristics in Wistar rats exposed within the Chernobyl NPP zone over a period of 30 days (the average radiation background level, 75, and at the soil surface, 115 mR/h; a cumulative dose, 57 rad/30 days, and for pregnant rats, 36 rad/20 days). The quantity of chromosome aberrations in bone marrow metaphases and the embryonal death rate were invariable; some cases of teratogenesis were, however, observed. The total number of karyocytes in the brain and the leukocyte content in the peripheral blood sometimes decreased. The changes in certain characteristics (such as the content of endogenous amines and thiols in the liver and spleen) of the endogenous radioresistance background (ERB) and the normalization of the ERB by the radioprotective agent MIGI-K were found.     

The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 3. The morphological and ultrastructural changes in the lungs of rats]

The morphological and ultrastructural changes revealed in the lungs of rats kept within the Chernobyl accident zone during the period of 6 to 24 months were shown to be uniform and multicomponent. The changes were found both in the respiratory and the vascular connective tissue. The inflammatory processes occurred with formation of pneumonic foci, hypo- and disatelectasis, emphysematous changes, impairment of interalveolar septa, and connective tissue cell proliferation. In the lung tissue, focal and diffuse lymphoid proliferates and, at later stages, lymphomatous changes were revealed.     

Radiobiology and the lessons of Chernobyl

The Chernobyl accident has marked the beginning of a new stage of radiobiology development and revealed scantiness of old concepts. One should (1) search for effective protectors against the long-term influence of low-level radiation and means of removal of radionuclides using criteria that differ principally from those used previously in selecting among nontoxic antioxidants, immunomodulators, and adaptogens; (2) study systematically the synergism of low doses of harmful agents and review the hygienic standardization system with due regard for the risk from their combinations; (3) consider comprehensively, on the basis of the experimental and clinical experience, the problem of "hot" particles and remote consequences of their influence on the respiratory and digestive systems; (4) study independently the problem of chronic stress as a combination of radiation effects and psycho-emotional consequences of the accident and living in the exposed areas; (5) consider it inadmissible to include in the B category the population of the districts influenced by the accident and to use the concept: "35 rads during the lifetime" in standardizing the radiation load; (6) organize a comprehensive analysis of the Chernobyl accident consequences for public health within the contaminated areas as well as for animals and plants using a single approved methodology and programme, the principle of "other equal conditions" being provided.     

Historical mutation rates predict susceptibility to radiation in Chernobyl birds

Extreme environmental perturbations are rare, but may have important evolutionary consequences. Responses to current perturbations may provide important information about the ability of living organisms to cope with similar conditions in the evolutionary past. Radioactive contamination from Chernobyl constitutes one such extreme perturbation, with significant but highly variable impact on local population density and mutation rates of different species of animals and plants. We explicitly tested the hypothesis that species with strong impacts of radiation on abundance were those with high rates of historical mutation accumulation as reflected by cytochrome b mitochondrial DNA base‐pair substitution rates during past environmental perturbations. Using a dataset of 32 species of birds, we show higher historical mitochondrial substitution rates in species with the strongest negative impact of local levels of radiation on local population density. These effects were robust to different estimates of impact of radiation on abundance, weighting of estimates of abundance by sample size, statistical control for similarity in the response among species because of common phylogenetic descent, and effects of population size and longevity. Therefore, species that respond strongly to the impact of radiation from Chernobyl are also the species that in the past have been most susceptible to factors that have caused high substitution rates in mitochondrial DNA.     

Proteins of the lupin family, binding molybdenum, tungsten, and radionuclide effluents from the Chernobyl Atomic Energy Station

Yellow lupine seeds were found to contain two proteins and a low molecular weight fraction possessing the ability to bind Mo, W and radionuclides from the Chernobyl nuclear power in vivo and the 185W isotope in vitro. These proteins differ in their electrophoretic mobility. The electrophoretically less mobile protein undergoes proteolytic degradation; the proteolytic product retains the ability to accumulate microelements.