[The genetic monitoring of populations of brown frogs inhabiting radionuclide-contaminated regions of the Republic of Byelarus]

Genetic monitoring of brown frog populations inhabiting radiocontaminated areas of Belarus (contamination range: 177-2331 kBq/m2 for 137Cs; 3.7-284 kBq/m2 for 90Sr) has shown that the frequency of aberrant metaphases in bone marrow cells of animals from the contaminated areas is 3 to 10 times as much as that of the control, aberration load of cells being also higher. The aberration spectrum differs from a spontaneous one. There is no strict dependence of the yield of cytogenetic damages on the contamination.

[The cytogenetic effect in the cells of the needles of the common pine from irradiation resulting from the accident at the Chernobyl Atomic Power Station]

The consequences of Pinus sylvestris irradiation were studied since 1987-1990. The chromosome aberrations in needle cells and morphological changes are annually observed at the same level, that confirms the continuous character of mutagenesis and morphogenesis. It is concluded that the big pool of damages is caused by radiation, one part of them is realized in chromosome aberration during the first vegetation after irradiation. The other part of them is transferred by division during the initial cell bud differentiation to the specialized cells and is realized to aberrations during the following vegetative periods.

[Automated classification system (ACS) for detection of high risk groups exposed to radiation]

The paper presents the results of using an experimental version of the automatic classifying system (ACS) based on unstatistical methods of recognizing the images with estimate calculation algorithms. According to 21 blood parameters obtained on an automatic analyser, ACS could divide, at higher than 90% significance, groups of persons living in the polluted areas of the towns of Klintsy and Zlynka who have accumulated mean radiation dose of 15 and 63 mZv, respectively. The results suggest that ACS may be used to divide subjects into risk groups in terms of exposures to unfavorable environmental factors.

[The dose dependence of the induction of chromosome aberrations in those who worked in the cleanup of the Chernobyl accident]

The method of biological dosimetry based on registration of frequency of chromosome aberrations in peripheral lymphocytes was proven to be a valuable technique for estimation of large absorbed doses. In the case of low absorbed doses or low dose rate the suitability of this method is restricted because of deficiency of suitable dose-response curve for yield of chromosome aberrations. In this work chromosome aberration rate was estimated in 31 ameliorators of the Chernobyl accident with the known data of physical dosimetry in the range of 12-30 cGy. Linear dependence of induction of chromosome aberrations was found in this dose range. The coefficients for induction of dicentrics and all unstable aberrations of chromosome type was found to be 1.4 +/- 0.4 and 7.2 +/- 1.2 per 100 cells per 1 Gy, respectively.

[Thyroid anti-membrane antibodies and antithyroglobulin antibodies of children in the city and province of Wrocław]

The purpose of the work was an assessment of thyroid function and determination of the development of antithyroid autoantibodies in children undergoing iodine prophylaxis after Chernobyl disaster. The level of T3 and T4 was determined by the RIA method, that of TSH by th immunoenzymatic method using Abbott kit, while antimembrane and antithyroglobulin antibodies were determined by the immunoenzymatic method using HTL-Plastomed kit. The studies were carried out in 844 children (433 boys and 411 girls) aged from 4 to 16 years, the selection of whom was described in our earlier report (12). Our studies demonstrated an increased level of T3 in 15.6% of the studied children and increased level of T4 in 12.7% of the cases. In most children the levels of hormones and TSH in the serum were normal. The antimembrane antibodies ATMA were present in 1.9% of the children (0.5% of the boys and 3.4% of the girls), while antithyroglobulin antibodies were found in 2.2% of the studied population (0.9% of the boys and 3.4% of the girls). No correlation was found between clinical picture, size of goitre, hormone level and the presence of thyroid autoantibodies. The studies indicate that radioactive contamination and iodine prophylaxis failed to cause permanent thyroid function disturbances in the studied population. The children in whom autoantibodies or abnormalities in hormone levels were found require further observation.

[The microbiocenosis of the large intestine in animals with constant radiation exposure in the area of the Chernobyl Atomic Electric Power Station]

State of microbiocenosis of large intestine in rats and furo subjected to constant combined irradiation has been studied in full-scale experiments in the emergency rooms of the Chernobyl NPP and in the nearest zone of its effect. The higher diversity of microflora (as compared to initial one), sharp increase of the amount of Candida genus fungi, a decrease of the number of bifidobacteria and increase of the amount of conditionally pathogenic flora were observed in rats with the dose of external irradiation of 1.43 Gr absorbed for 14 days. The expressed associative character of disbioses is distinctly traced. In furo affected by the radion exceeding the background level feeding with products contaminated by radionuclides leads to changes whose individual character corresponds to the picture of disbiosis under radiation injury.

[The micronucleus frequency in the somatic cells of murine rodents residing in a 30-kilometer area of the Chernobyl Atomic Electric Power Station]

The chromosome aberration frequency in murine somatic cells was studied. Animals from natural populations as well as laboratory mice exposed within the ten-kilometers zone of the Chernobyl accident were examined. Increase in micronuclei rate in bone marrow cells, erythrocytes of peripheral blood and hepatocytes was found in animals exposed to more high background radiation. Under chronic exposure the pattern of effect dependence on dose rate was similar both in somatic and sex cells.

[The reactions of the upper respiratory pathways to low doses of ionizing radiation]

The state of upper respiratory tract, non-specific cell resistance and immune status were studied in persons who participated in liquidation of the Chernobyl APS disaster consequences. The prolonged influence of factors caused by small doses of ionizing irradiation leads to mucosa affection of upper respiratory tract, considerable reduction of phagocytic and antiviral activity of monocytes and worsening of the immune status of organism. The data obtained during researches explains the considerable increase of ARD among these persons.

[The results of a cytogenetic examination performed in different years on those who worked in the cleanup of the aftermath of the accident at the Chernobyl Atomic Electric Power Station]

Persons participated in the Chernobyl accident amelioration in the years of 1986-1987 were examined cytogenetically either in 1987 (group 1) or in 1990-1992 (group 2). The frequency of chromosome aberrations in cultured peripheral lymphocytes is found to be significantly lower in group 2 in comparison with group 1, being increased in both exposed groups as compared to the control one. The data are obtained in favour of hypothesis on chromosome instability of exposed individuals. On the base of cytogenetic data the collective dose received by amelioraters was calculated.

[Management of accidental internal exposure]

Radionucleides can penetrate into the body via the lung, the digestive tract, wounds and sometimes through healthy skin. Once they have penetrated the body, they can either remain localized at the site of entry or be rapidly metabolized. The risk is late effects. Radioelements must be eliminated as rapidly as possible decreasing the exposure proportionally. The effectiveness of the treatment depends on early institution. Nevertheless, emergency intensive care or surgery may be required. As soon as possible, explorations must be carried out to evaluate the level of contamination (human spectrometry, radiotoxicological examinations) and to start treatment. Modalities include non-specific techniques (lavage, insolubilization, laxatives) and specific techniques such as complexation or isotopic dilution (iodine for iodine, Prussian blue for cesium, DTPA for plutonium, Diamox or sodium bicarbonate for uranium). Surgical cleaning of wounds and burns is an excellent means of decontamination. External contamination is often associated. Further contamination must be prevented immediately.

Pregnancy outcome in Sweden after the Chernobyl accident

OBJECTIVE

To study pregnancy outcome including development of childhood cancer in areas within Sweden with the highest radioactive fallout after the Chernobyl accident in 1986.

METHODS

Various Swedish health registries were used in order to identify all pregnancies and their outcome in Sweden according to the measured radioactive fallout.

RESULTS

A reduction in conception rate occurred after the accident, as well as possible increase in induced abortion rate during the fall after the accident. No changes in the rate of spontaneous abortions or congenital malformations occurred in pregnancies exposed at the time of the accident. There was a temporary increase in low birth weight which could well be random. Among infants conceived after the accident, a slight excess of Down syndrome infants was found in the most exposed areas but this observation is based on small numbers. No certain excess of childhood cancer was seen in the most exposed areas, but three infants, in utero at the time of the accident, developed leukemia.

CONCLUSIONS

No major effects on pregnancy outcome were seen but the indicated increase in Down syndrome and childhood leukemia--if not random--could be a result of radioactive exposure.

[Disorders of interferon status in bronchopulmonary diseases in children living under conditions of elevated background radiation]

Impairments in the interferon status of children with chronic and recurring diseases of the respiratory organs were investigated and its correction was shown possible with the use of alpha 2-interferon (reaferon). Suppression of the interferon-producing capacity of the immunocytes was observed in all the cases of the disease aggravation. The level of the suppression correlated with the severity of the infection. In the patients affected by radiation the suppression of the interferonogenesis was more marked. However, in these cases no dependence of the detected impairments in the interferon status on the level of the radiation pollution of the territory of the children residence was shown. The inclusion of reaferon to the basal therapy resulted in a significant increase of the alpha-interferon production in the cases of bronchial asthma and asthmatic bronchitis as well as its recovery to the normal in the cases of recurring bronchitis and chronic pneumonia. In all the cases of bronchopulmonary diseases only a tendency towards normalization of the alpha-interferon indices was recorded.

[The formation of an adaptive response in children exposed to the effect of low doses of radiation as a result of the accident at the Chernobyl Atomic Electric Power Station]

The ability of lymphocytes to form an adaptive response in cells of the children which were exposed to small radiation doses during the Chernobyl accident was studied by hydroxyapatite chromatography of cell lysates. Ten children living in the area with high radiation level (Bryansk region) and seventeen children living in the area with natural radiation level (Bryansk region too) were examined. No difference in cell ability to form adaptive response was found in both children group.

[An ecological and geographical test of the seed offspring of Viola matutina Klok. from a 30-kilometer area of the accident at the Chernobyl Atomic Electric Power Station]

The generation of seeds of two populations of Viola matutina Klok. sampled from plants growing within the thirty-kilometers zone of the Chernobyl accident (the reproduction of seeds in 1988) was investigated in the north nursery in Syktyvkar. The decrease of sterile pollen and embryonic lethality among the plants from the strongly contaminated site (exposure rate (1075-1434) pC/(kg.s) May 1987) was registered. It is suggested that this phenomenon is the result of the elimination of genetic damages in the course of seed forming in this population under radiation stress.

Radionuclides in domestic and imported foods in the United States, 1987-1992

Findings from the U.S. Food and Drug Administration's Radionuclides in Foods program are summarized for foods collected between October 1, 1986, and September 30, 1992. Concentrations of radionuclide activity in the Total Diet Study and reactor-survey foods were in Range 1 or low in Range II of the surveillance and control recommendations of the Federal Radiation Council; no control actions were suggested. Dietary intake of 90Sr continued the general decline observed since 1961. Approximately 2600 test portions of imported foods were analyzed for contamination associated with the Chernobyl nuclear accident. Concentrations of radionuclide activity were below limits of detection for the vast majority of the imported food test portions but were above the levels of concern for 23 portions. Since 1986, the fraction of imported food test portions having measurable amounts of contamination has steadily declined, as have the average concentrations of radionuclide activity; however, contamination is still occasionally found. Continued monitoring of both domestic and imported foods is planned.

[The possibilities of using biological dosimetry methods for the retrospective assessment of dosages in relation to the sequelae of the accident at the Chernobyl Atomic Electric Power Station. An assessment of the dosages based on an analysis of unstable chromosome aberrations]

The problem of retrospective dose assessment in connection with the Chernobyl accident is discussed. Existing methods of dose quantification based on the analysis of unstable aberrations in blood lymphocytes are discussed in details. Starting from the own data it is concluded that unstable aberration technique could not be applied to verify individual doses for ameliorators as well as for inhabitants of contaminated areas.

[The dynamics of the frequency of cytogenetic disorders in micropopulations of murine rodents inhabiting the region of the accident at the Chernobyl Atomic Electric Power Station]

Cytogenetic examination of some species of Muridae from Chernobyl region was carried out in 1986-1993. It was revealed that the dynamic of cytogenetic aberrations in cells of animals from territories with distinct level of radioactive contamination differed.

[The adaptive reaction of the blood lymphocytes in persons subjected to chronic radiation exposure at low doses]

The changes in the PHA-stimulated human blood lymphocytes of the peoples from Moscow and from polluted after Chernobyl disaster Bryansk region were studied. The decrease in lymphocyte mitotic index in residents from polluted regions was revealed. Moscow population was not distinguished from Bryansk region population by the frequency of cells with micronuclei. There was also no difference in frequency of micronuclei after 1 Gy irradiation of the these populations. The adaptive response (irradiation with a dose of 0.05 Gy followed by 1.0 Gy irradiation 5 hours later) was studied. The decrease in the number of individuals with adaptive response and appearance of the individuals with increased radiosensitivity in the population of polluted regions were observed. There was no such subpopulation among the Moscow residents. So, firstly, low dose chronic irradiation is not an adaptive factor; secondly, the determination of adaptive response can be methodological procedure for the revealing the changes which were induced by low dose chronic irradiation (accompanied by other environment agents).

Strontium-90 concentrations in human teeth in south Ukraine, 5 years after the Chernobyl accident

Approximately 1000 human teeth, collected in South Ukraine, in 1990-1991, were measured for 90Sr concentration. The teeth were grouped into 18 samples according to the age and sex of the donors. Measured levels of 90Sr concentrations were lower by a factor of 10 than measurements taken in the mid-1960s and mid-1970s. An interesting feature of the data is a 3-fold enhancement of contamination levels in the 25-45 year-old age group of the male population. A possible explanation for this anomaly is that this age group contains a significant number of men who were mobilized immediately after the Chernobyl accident for clean-up operations within the 30-km zone around the damaged nuclear power plant.

The transfer of cesium-137 and strontium-90 from soil to food crops after the Chernobyl accident

The soil to plant transfer of 137Cs and 90Sr was studied at seven locations in Finland over 4 and 2 years, respectively. The plant/soil concentration ratio of 137Cs for field crops in the southern area (60 degrees-63 degrees N) ranged from 0.001 to 0.26 and in the northern area (64 degrees-67 degrees N) from 0.01 to 2.29, and that of 90 Sr in the whole area from 0.02 to 2.44. The mean concentration ratio of 90Sr was about nine times higher than that of 137Cs in the southern area. The concentration ratio of 137Cs for leaf vegetables fluctuated between years, and that for carrot, potato and especially cereals decreased gradually after the first year. In the fourth year, the mean concentration ratio of 137Cs in the southern area was about 60% of the first year value for coarse mineral soils and 80% of that for clay and silt soils. There was no difference in the average 90Sr ratios between the 2 years studied. The concentration ratio of 137Cs was lower for clay and silt soils than for coarse mineral soils, and the 90Sr ratio was lowest for organic soils. The concentration ratio of 137Cs for vegetables and grain decreased in the order: lettuce, cabbage > carrot, potato > cereals, onion; for fruits in the order: blackcurrant > strawberry > apple, and the concentration ratio of 90Sr decreased in the order: lettuce, cabbage > carrot, onion > cereals > potato.

Cs-137 content in the mushrooms of radioactive contaminated zones of the European part of the CIS

Samples of different species of mushrooms were collected in the forests contaminated by Chernobyl (ChNPP) accident fallout debris. Sampling sites were located at a distance of 5-200 km from Chernobyl NPP. Transfer factors (TF) for Cs-137 from soil to mushrooms varied from 12 to 5060 nCi kg-1/Ci km-2; TF variability depended on the distance from ChNPP, mushroom species and growth conditions. The highest concentrations of Cs-137 were observed in Paxillus involutus and Xerocomus badius. These species are suggested as bioindicators of radioactive contamination.