Cytogenetic biomonitoring carried out in a village (Dolon) adjacent to the Semipalatinsk nuclear weapon test site

The Semipalatinsk region (Kazakhstan Republic) has been affected by extensive radioactive contamination due to more than 450 nuclear tests of which almost 100 were exploded in the atmosphere. The present results refer to cytogenetic assessments in a study cohort of the population of Dolon, a settlement located on the NE boundary of the nuclear weapon test site, which was exposed to elevated doses of ionising radiation primarily due to the first Soviet nuclear test in 1949. Conventional cytogenetic analyses were carried out on 21 blood samples from individuals (more than 50 years old) living in Dolon since the very beginning of nuclear testing. A matched control group included 20 individuals living in non-contaminated areas. Higher frequencies of chromosome aberrations were found in the Dolon cohort compared to the control group, even though they remain within the range of the background levels reported for large normal human population studies on elderly individuals. Received: 24 May 2000 / Accepted: 1 November 2000     

Population dose near the Semipalatinsk test site

To determine the consequences of atmospheric atomic bomb tests for the population in the surroundings of the former nuclear weapons test site near Semipalatinsk in Kazakhstan, a pilot study was performed by an international cooperation between Kazakh, French, Czech and German institutions at two villages, Mostik and Maisk. Together with Kazakh scientists, eight experts from Europe carried out a field mission in September 1995 to assess, within the framework of a NATO supported project, the radiological situation as far as external doses, environmental contamination and body burden of man were concerned. A summary of the results obtained is presented. The actual radiological situation near the test site is characterized by fallout contaminations. Cs was found in upper soil layers in concentrations similar to those of the global fallout. Also Sr, Am and Co were observed. The resulting present dose to the population is low. Mean external doses from soil contamination for Maisk and Mostik (0.60–0.63 mSv/ year) presently correspond to mean external doses in normal environments. Mean values of the annual internal doses observed in these two villages are below 2 μSv/year for ⁹⁰Sr. For other radionuclides the internal doses are also negligible. Received: 12 March 1998 / Accepted in revised form: 1 August 1998     

Analysis of FISH-painted chromosomes in individuals living near the Semipalatinsk nuclear test site

The Semipalatinsk nuclear test site (STS) is located in the Republic of Kazakhstan. A total of 498 nuclear weapons tests were conducted in this area between 1949 and 1989. The radiation exposure to people who lived close to the STS resulted mostly from the above-ground explosions. Blood samples for chromosome analysis were obtained from 10 subjects who were born before the first explosion in August 1949 and lived continuously in the village of Dolon. The individual calculated effective doses were about 3 Sv. Chromosomes 2, 4 and 8 were painted by means of the FISH technique. In total, 22,240 cells were analyzed. The mean frequency of translocations in the subjects who were irradiated during childhood (2.4/1000 cells) did not differ from the control value (3.1 translocations/1000 cells). It is assumed, therefore, that the calculated physical dose is too high. A significantly increased level of complex cells was determined, however, and this was assumed to have been induced in circulating lymphocytes. The reason for this may be the incorporation of radionuclides from fallout which were not distributed homogeneously within the body, but accumulated instead in tissues that were well supplied with peripheral blood.     

Assessment of soil degradation in areas of nuclear explosions at the Semipalatinsk nuclear test site

The degree of the soil cover degradation at the Balapan and Experimental Field test sites was assessed on the basis of the Allium-test of soil toxicity and international guidelines on the radioactive restriction of solid materials (IAEA, 2004) and the environment (Smith, 2005). Large scale soil-cover degradation maps (1: 25000) were made. The main part of the mapped area contains highly contaminated toxic degraded soil. It was found that the relationship between soil toxicity and total radionuclide activity concentration is described by power functions. When the calculated value (413–415 Bq/kg of air-dried soil) increases, the soil becomes toxic to plants. This value is 7.8 times higher than the maximum value for background territories (53 Bq/kg) surrounding the SNTS. The Russian sanitary and hygienic guidelines (Radiation safety standards, 2009; Sanitary regulations of radioactive waste management, 2003) underestimate the degree of soil radioactive contamination for plants.     

Analysis of genetico-demographic structure of rural populations living near the Semipalatinsk nuclear test site]

Rural populations neighboring the Semipalatinsk nuclear test site were used as a model to develop and test an integrated population-genetic approach to analysis of the medical genetic situation and environmental conditions in the areas studied. The contributions of individual factors of population dynamics into the formation of the genetic load were also assessed. The informative values of some genetic markers were estimated. Based on these estimates, a mathematical model was constructed that makes it possible to calculate numerical scores for analysis of the genetic loads in populations differing in environmental exposure.     

Reconstruction of local fallout composition and gamma-ray exposure in a village contaminated by the first USSR nuclear test in the Semipalatinsk nuclear test site in Kazakhstan

After the disintegration of the USSR in end of 1991, it became possible for foreign scientists to visit Kazakhstan, in order to investigate the radiological consequences of nuclear explosions that had been conducted at the Semipalatinsk nuclear test site (SNTS). Since the first visit in 1994, our group has been continuing expeditions for soil sampling at various areas around SNTS. The current level of local fallout at SNTS was studied through γ-spectrometry for ¹³⁷Cs as well as α-spectrometry for ^239,240Pu. Average values of soil inventory from wide areas around SNTS were 3,500 and 3,700 Bq m^?2 for ¹³⁷Cs and ^239,240Pu, respectively, as of January 1, 2000. The average level of ¹³⁷Cs is comparable to that in Japan due to global fallout, while the level of ^239,240Pu is several tens of times larger than that in Japan. Areas of strong contamination were found along the trajectories of radioactive fallout, information on which was declassified after the collapse of the USSR. Our recent efforts of soil sampling were concentrated on the area around the Dolon village heavily affected by the radioactive plume from the first USSR atomic bomb test in 1949 and located 110 km east from ground zero of the explosion. Using soil inventory data, retrospective dosimetry was attempted by reconstructing γ-ray exposure from fission product nuclides deposited on the ground. Adopting representative parameters for the initial ¹³⁷Cs deposition (13 kBq m^?2), the refractory/volatile deposition ratio (3.8) and the plume arrival time after explosion (2.5 h), an absorbed dose in air of 600 mGy was obtained for the 1-year cumulative dose in Dolon village, due to the first bomb test in 1949. Considering possible ranges of the parameters, 350 and 910 mGy were estimated for high and low cases of γ-ray dose in air, respectively. It was encouraging that the deduced value was consistent with other estimations using thermal luminescence and archived monitoring data. The present method can be applied to other settlements affected by local fallout from SNTS.     

Radiostrontium contamination of soil and vegetation within the Semipalatinsk test site

The Semipalatinsk nuclear test site (STS) in the Republic of Kazakhstan was an important site for testing atomic bombs and other civil and military nuclear devices of the former Soviet Union. Results are presented from investigations on the extent of radiostrontium contamination in soils and vegetation at the technical areas of the STS, where the tests were conducted and in pastures used by farmers for grazing animals or for hay production. Our data are compared with those reported largely in the recent Russian language literature that has been reviewed. The extent of ⁹⁰Sr contamination of soil is highly variable over the STS with the highest values associated with the technical areas, particularly the Degelen mountains. Recently measured values in both the present data and the Russian language literature confirm the relatively high current contamination of soil and vegetation in the vicinity of tunnels and associated watercourses in the Degelen area. The proportion of ⁹⁰Sr in soil which could not be extracted with 6 M HCl was only an average of 20%, which is low compared to other test site areas and possibly indicates a relatively high mobility in this area, because the ⁹⁰Sr is derived from leakage from explosion tunnels along watercourses rather than being associated with fused silicates. A comparison of relative activity concentrations in soil and vegetation suggests that the transfer of ⁹⁰Sr to vegetation on the STS is high compared to that of ¹³⁷Cs and plutonium.     

Chromosomal instability parameters in the population affected by nuclear explosions at the Semipalatinsk nuclear test site

A population genetic survey of 149 persons who were born and have permanently lived in the contaminated zones of the Semipalatinsk region has been performed. A cytogenetic study has demonstrated that the frequency of aberrant cells is 1.7-3 times higher than control parameters. The total frequencies of chromosome aberrations are 3.43 +/- 0.48, 3.1 +/- 0.3, 1.8 +/- 0.2, and 1.15 +/- 0.17 aberrations per 100 cells in the populations of the extreme radiation risk (ERR), maximum radiation risk (MaxRR), minimum radiation risk (MinRR), and control zones, respectively. The high chromosome aberration rate in all three zones of radiation risk has been detected mainly due to radiation-induced chromosome markers, including paired fragments (1.2 +/- 0.2, 0.94 +/- 0.13, and 0.43 +/- 0.06 per 100 cells, respectively), dicentric and ring chromosomes (0.44 +/- 0.04, 0.45 +/- 0.07, and 0.11 +/- 0.02 per 100 cells, respectively), and stable chromosome aberrations (0.74 +/- 0.16, 0.8 +/- 0.1, and 0.63 +/- 0.13 per 100 cells, respectively). The qualitative spectra of the cytogenetic lesions observed in these groups indicate a mutagenic effect of ionizing radiation on chromosomes in the populations studied.     

A registry for exposure and population health in the Altai region affected by fallout from the Semipalatinsk nuclear test site

A registry of the rural population in the Altai region exposed to fallout from nuclear tests at the Semipalatinsk test site (STS) was established more than four decades after the first Soviet nuclear explosion on August 29, 1949. Information about individuals living in an exposed and a control area was collected using all available local sources, such as kolkhoz documentation, school registries, medical treatment records and interviews with residents. As a result, a database comprising an exposed group of 39 179 individuals from 53 Altai region villages, 6769 external and 3303 internal controls was compiled. For several settlements, effective dose estimates reached the level of 1.5 Sv, while the average effective dose estimate in the exposed group was 340 mSv. Dosimetric data, vital status information and health records gathered at rayon and village medical facilities are held in the registry. Cause-of-death information for deceased residents is obtained from death registration forms archived at the Altai region vital statistics office. At present, a follow-up of approximately 40% of the population exposed in 1949 has been done. More will be added by searching for migrants to the larger towns of the Altai region, i.e. Barnaul, Rubtsovsk and Biisk. In order to assess the influence of radiation exposure, analytical studies with a case-control design for stomach and lung cancer are currently being prepared. The number of known cases is sufficient to detect an odds ratio of 1.5 at the 95% confidence level. Epidemiological studies in populations affected by fallout from STS may be equally important to the atomic bomb survivors’ study for the direct quantification of radiation effects. The range of exposure rates experienced will extend the acute high-dose-rate findings from Hiroshima/Nagasaki towards acute and protracted lower exposures, which are more relevant for radiation protection issues. Received: 3 March 1999 / Accepted in revised form: 8 June 1999     

Glycophorin A somatic cell mutations in a population living in the proximity of the Semipalatinsk nuclear test site

The glycophorin A (GPA) somatic mutation assay was performed to evaluate the magnitude of exposure to ionizing radiation among the human population living in the vicinity of the Semipalatinsk nuclear test site in Kazakhstan. All together, 113 blood samples were analyzed from three generations of people living in villages that were under the trail of the radioactive cloud from the first Soviet surface nuclear test performed in August 1949 and from later tests. The oldest generation (P0) lived in the area at the time of testing, whereas the younger generations (F1, F2) were exposed to smaller doses from the residual fallout and later tests. The GPA assay did not reveal significant differences in the variant cell frequencies for all subjects selected from the Semipalatinsk area compared with 74 matched controls living in a noncontaminated area. However, a significant increase (P < 0.05) in the mean allele-loss ON variant frequency was observed among the exposed P0 generation (12 x 10(-6)) in comparison to controls (7 x 10(-6)). Considering the sensitivity of the GPA assay, the results suggest that the mean dose to the P0 generation of the affected villages was relatively low, a finding which is in accordance to the conclusions obtained from other biological assays performed on the same population.     

Stable chromosome aberrations in the lymphocytes of a population living in the vicinity of the Semipalatinsk nuclear test site

SalomaTranslocation analysis using FISH (fluorescence in situ hybridization) chromosome painting was performed to evaluate the magnitude of exposure to ionizing radiation among the human population living close to the Semipalatinsk nuclear test site in Kazakhstan. We studied two generations of people living in villages that were in the path of the radioactive cloud from the first Soviet surface nuclear test performed in August 1949 and from later tests. The older generation (P(0)) lived in the area at the time of testing, and the younger generation (F(1)) was exposed to smaller doses from the residual fallout and later tests. In both P(0) and F(1) generations, similar translocation frequencies were observed in persons living in either the Semipalatinsk area or a noncontaminated area. Assuming translocation stability in peripheral blood lymphocytes over several decades, these findings suggest that on average, the magnitude of exposure of this cohort in the Semipalatinsk area has been considerably smaller than that reported in the literature. Previously reported doses of the order of 1-4.5 Gy (mean 2.9 Gy in the P(0) generation) cannot be confirmed by the present data.     

The Semipalatinsk nuclear test site: a first assessment of the radiological situation and the test-related radiation doses in the surrounding territories

As a result of atmospheric nuclear tests at the Semipalatinsk test site `Polygon', adjacent territories were contaminated by radionuclide fallout. The population of some districts in the Semipalatinsk oblast were exposed to elevated levels of radiation. Contamination and exposure mostly resulted from early atmospheric tests. The radiological situation of the Semipalatinsk oblast is described. Effective dose estimates due to external and internal exposure attributable to the 1949 and 1953 tests in villages near the Polygon range from 70 mSv to 4470 mSv. Received: 13 February 1997 / Accepted in revised form: 1 July 1997     

Prediction of 137Cs accumulation in animal products in the territory of Semipalatinsk test site

The paper describes mathematical models for 137Cs behavior in the organism of horses and sheep pasturing on the bording area to the testing area "Ground Zero" of the Semipalatinsk Test Site. The models are parameterized on the base of the data from an experiment with the breeds of animals now commonly encountered within the Semipalatinsk Test Site. The predictive calculations with the models devised have shown that 137Cs concentrations in milk of horses and sheep pasturingon the testing area to "Ground Zero" can exceed the adopted standards during a long period of time.     

Prediction of 137Cs behaviour in the soil-plant system in the territory of Semipalatinsk test site

A mathematical model of 137Cs behaviour in the soil-plant system is presented. The model has been parameterized for the area adjacent to the testing area Ground Zero of the Semipalatinsk Test Site. The model describes the main processes responsible for the changes in 137Cs content in the soil solution and, thereby, dynamics of the radionuclide uptake by vegetation. The results are taken from predictive and retrospective calculations that reflect the dynamics of 137Cs distribution by species in soil after nuclear explosions. The importance of factors governing 137Cs accumulation in plants within the STS area is assessed. The analysis of sensitivity of the output model variable to changes in its parameters revealed that the key soil properties significantly influence the results of prediction of 137Cs content in plants.     

The Semipalatinsk nuclear test site: a first analysis of solid cancer incidence (selected sites) due to test-related radiation

Since 1956, cancer incidences have been analysed in several rayons of the Semipalatinsk oblast, with cross-sectional analyses being conducted every 5 years. Data on different tumor localizations were recorded within a heavily contaminated so-called main area of nine villages (estimated average effective equivalent dose about 2000 mSv) and a so-called control area (estimated average effective equivalent dose about 70 mSv), each including approximately 10 000 persons. Up to 1970, the excess cancer incidence in the exposed villages was observed to have increased; after 1970, a decrease was noted, followed by a second increase in the late 1980s. The main sites of excess cancer included the esophagus, stomach, and liver. Up to 1970, the esophagus cancer incidence was predominant, but it decreased thereafter, while the incidence of stomach and liver cancers increased. The second peak of excess cancer rates was mainly due to lung, breast, and thyroid carcinomas.     

Assessment of soil degradation in regions of nuclear power explosions at Semipalatinsk Nuclear Test Site

Degree of the soil cover degradation at the "Balapan" and "Experimental field" test sites was assessed based on Allium-test of soil toxicity results and international guidelines on radioactive restriction of solid materials (IAEA, 2004) and environment (Smith, 2005). Soil cover degradation maps of large-scale (1 : 25000) were made. The main part of the area mapped belongs to high-contaminated toxic degraded soil. A relationship between the soil toxicity and the total radionuclide activity concentrations was found to be described by power functions. When the calculated value (equal to 413-415 Bq/kg of air dry soil) increases, the soil becomes toxic for plants. This value is 7.8 times higher than the maximal value for background territories (53 Bq/kg) surrounding SNTS. Russian sanitary and hygienic guidelines (Radiation safety norms, 2009; Sanitary regulations of radioactive waste management, 2003) underestimate the degree of soil radioactive contamination for plants.     

Genetic diversity in three perennial grasses from the Semipalatinsk nuclear testing region of Kazakhstan after long-term radiation exposure

The extent and structure of the genetic diversity of plant populations from the Semipalatinsk region of Kazakhstan, adjacent to a former major nuclear test site, have been studied using RAPD (Random Amplified Polymorphic DNA) marker analyses. The DNAs from three perennial species, Stipa capillata, Hordeum bogdanii, and Agropyron pectinatum, each collected from heavily (HPZ), moderately (MPZ) and lightly polluted zones (LPZ) have been analyzed using RAPDs. The results show a significantly higher level of variability in plants collected from the highest radiation pollution area compared with the moderately and lightly radiation contaminated zones for A. pectinatum and H. bogdanii. Variation was five times as higher in heavily exposed H. bogdanii, and two times higher in A. pectinatum populations compared to their lightly contaminated populations. H. bogdanii appears to be very sensitive to radiation and as such is a good indicator species for mapping radiation pollution at nuclear test sites or nuclear accidents.     

Nitrification and nitrous oxide production potentials in aerobic soil samples from the soil profile of a Finnish coniferous site receiving high ammonium deposition

Abstract Using aerobic soil slurry technique nitrification and nitrous oxide production were studied in samples from a pine site in Western Finland. The site received atmospheric ammonium deposition of 7–33 kg N ha⁻¹ a⁻¹ from a mink farm. The experiments with soil slurries showed that the nitrification potential in the litter layer was higher at pH 6 than at pH 4. However, the nitrification potentials in the samples from the organic and mineral horizons at pH 6 and 4 were almost equal. Also N₂O was produced at a higher rate at pH 6 than at pH 4 in slurries of the litter layer samples. The reverse was true for samples from the organic and mineral horizons. The highest N₂O production and nitrification rates were measured in the suspensions of litter layer samples. Nitrification activity in field-moist soil samples was lower than the activity in the slurries indicating that the availability of ammonium limited nitrification in these soils. Acetylene (2.5 kPa) retarded nitrification activity (70-–100%) and N₂O production (40 – 90%) in soil slurries. Acetylene inhibited the N₂O production by 40–60% during the first 3 days after its addition to field-moist samples incubated in aerobic atmosphere. After 3 days the inhibition became much lower (4–5%). The results indicate that, in soil profiles of boreal coniferous forests receiving ammonium deposition, chemolithotrophic nitrification may have importance in the N₂O production, and that changes in soil pH affect differently nitrification as well as N₂O production in litter and deeper soil layers.