Assessment of the radiological impact of gamma and radon dose rates at former U mining sites in Tajikistan.

An assessment of the radiological situation due to exposure to gamma radiation, radon ((222)Rn) and thoron ((220)Rn) was carried out at former uranium (U) mining and processing sites in Taboshar and at Digmai in Tajikistan. Gamma dose rate measurements were made using various field instruments. (222)Rn/(220)Rn measurements were carried out with field instruments for instantaneous measurements and then discriminative (222)Rn/(220)Rn solid state nuclear track detectors (SSNTD) were used for longer representative measurements. The detectors were exposed for an extended period of time in different outdoor and indoor public and residential environments at the selected U legacy sites. The results showed that gamma, (222)Rn and (220)Rn doses were in general low, which consequently implies a low to relatively low radiological risk. The radiation doses deriving from external radiation (gamma dose rate), indoor (222)Rn and (220)Rn with their short-lived progenies did not exceed national or international standards. At none of the sites investigated did the average individual annual effective doses exceed 10 mSv, the recommended threshold value for the general public. A radiation hazard could be associated with exceptional situations, such as elevated exposures to ionizing radiation at the Digmai tailings site and/or in industrial facilities, where gamma and (222)Rn/(220)Rn dose rates could reach values of several 10 mSv/a. Current doses of ionizing radiation do not represent a hazard to the health of the resident public, with the exception of some specific situations. These issues should be adequately addressed to further reduce needless exposure of the resident public to ionizing radiation.

Assessment of the radiological impact of gamma and radon dose rates at former U mining sites in Central Asia.

An assessment of the radiological situation due to exposure to gamma radiation, radon and thoron was carried out at selected former uranium mining and processing sites in the Central Asian countries of Kazakhstan, Kyrgyzstan, Uzbekistan and Tajikistan. Gamma dose rate measurements were made using various field instruments and radon/thoron measurements were carried out using discriminative radon ((222)Rn)/thoron ((220)Rn) solid state nuclear track detectors (SSNTD). The detectors were exposed for an extended period of time, including at least three seasonal periods in a year, in different outdoor and indoor public and residential environments at the selected uranium legacy sites. The results showed that gamma, Rn and Tn doses were in general low, which consequently implies a low/relatively low radiological risk. The major radiation hazard is represented by abandoned radioactive filtration material that was being used as insulation by some Minkush residents (Kyrgyzstan) for a longer period of time. Annual radiation doses of several hundred mSv could be received as a consequence of using this material domestically. In addition, the gamma and Rn/Tn dose rates at Digmai, Tajikistan, could reach values of several 10 mSv/a. The doses of ionizing radiation deriving from external radiation (gamma dose rate), indoor radon and thoron with their short-lived progenies in several cases exceeded the recommended annual effective dose threshold level of 10 mSv. At none of the sites investigated did the individual annual effective doses exceed 30 mSv, the internationally recommended value for considering intervention. Current doses of ionizing radiation do not represent a serious hazard to the health of the resident public, but this issue should be adequately addressed to further reduce needless exposure of the resident public to ionizing radiation.

Assessment of the radiological impact of gamma and radon dose rates at former U mining sites in Kyrgyzstan.

An assessment of the radiological situation due to exposure to gamma radiation, radon and thoron was carried out at the former uranium mining and processing sites in Shekaftar, Minkush and Kadji Sai in Kyrgyzstan. Gamma dose rate measurements were made using various field instruments and radon/thoron measurements were carried out using discriminative radon ((222)Rn)/thoron ((220)Rn) solid state nuclear track detectors (SSNTD). The detectors were exposed for an extended period of time including at least three seasonal periods in a year, in different outdoor and indoor public and residential environments at the selected uranium legacy sites. The results showed that gamma, Rn and Tn doses were in general low, which consequently implies a low/relatively low radiological risk. The major radiation hazard is represented by abandoned radioactive filtration material that was being used as insulation by some Minkush residents for a longer period of time. Annual radiation doses of several hundred mSv could be received as a consequence of using this material in their houses. The radiation doses deriving from external radiation (gamma dose rate), indoor radon and thoron with their short-lived progenies in several cases exceeded national as well as international standards. Current doses of ionizing radiation do not represent any serious hazard to the health of the resident public, but this issue should be adequately addressed to further reduce needless exposure of resident public to ionizing radiation.

Environmental impact assessment of radionuclide and metal contamination at the former U site at Kadji Sai, Kyrgyzstan.

During 1949-1967, a U mine, a coal-fired thermal power plant and a processing plant for the extraction of U from the produced ash were operated at the Kadji Sai U mining site in Tonsk district, Issyk-Kul County, Kyrgyzstan. The Kadji Sai U legacy site represents a source of contamination of the local environment by naturally occurring radionuclides and associated trace elements. To assess the environmental impact of radionuclides and trace metals at the site, field expeditions were performed in 2007 and 2008 by the Joint collaboration between Norway, Kazakhstan, Kyrgyzstan, Tajikistan (JNKKT) project and the NATO SfP RESCA project. In addition to in situ gamma and Rn dose rate measurements, sampling included at site fractionation of water and sampling of water, fish, sediment, soils and vegetation. The concentrations of radionuclides and trace metals in water from Issyk-Kul Lake were in general low, but surprisingly high for As. Uptake of U and As was also observed in fish from the lake with maximum bioconcentration factors for liver of 1.6 and 75, respectively. The concentrations of U in water within the Kadji Sai area varied from 0.01 to 0.05 mg/L, except for downstream from the mining area where U reached a factor of 10 higher, 0.2 mg/L. Uranium concentrations in the drinking water of Kadji Sai village were about the level recommended by the WHO for drinking water. The (234)U/(238)U activity ratio reflected equilibrium conditions in the mining pond, but far from equilibrium outside this area (reaching 2.3 for an artesian well). Uranium, As and Ni were mainly present as low molecular mass (LMM, less than 10 kDa) species in all samples, indicating that these elemental species are mobile and potentially bioavailable. The soils from the mining sites were enriched in U, As and trace metals. Hot spots with elevated radioactivity levels were easily detected in Kadji Sai and radioactive particles were observed. The presence of particles carrying significant amount of radioactivity and toxic trace elements may represent a hazard during strong wind events (wind erosion). Based on sequential extractions, most of the elements were strongly associated with mineral matter, except for U and As having a relatively high remobilization potential. Low Kd was obtained for U (3.5 × 10(2) L/kg d.w.), intermediate Kds (~3 × 10(3) L/kg d.w.) were obtained for (226)Ra, As and Ni, while a high Kd (2.2 × 10(5) L/kg d.w.) were obtained for Pb. The accumulation of metals in fish gills reflected the LMM species in the Issyk-Kul water, and did not show any bioaccumulation. The muscle Hg concentrations in all fish species were low and did not represent any health risk even for groups at risk. Total gamma and Rn dose rate to man amounted to about 12 mSv/y, while the highest calculated dose rate for non-human species based on the ERICA Assessment Tool were obtained in terrestrial plants (164 µGy/h) due to the Ra exposure. The results obtained showed that radiation doses to resident public at all of the investigated sites in the Kadji Sai area were in general relatively low. Low radiological risk and no detrimental health impact on resident public can be expected at these sites. However, exposure to Rn and Tn in the living environment can be further reduced by implementing simple countermeasures such as ventilation of dwelling cellars. More focus in the Kadji Sai area should probably be put on trace elements, especially the As uptake in fish in Lake Issyk-Kul.

Environmental impact assessment of radionuclide and metal contamination at the former U sites Taboshar and Digmai, Tajikistan.

Uranium (U) ore mining and processing were initiated in the former Soviet Republics of Tajikistan after the Second World War as part of the USSR nuclear weapon programme. The U mine in Taboshar was opened in 1936, and mining took place from 1945 to 1965, while the Digmai tailings dump was exploited during 1963-1993. The mining, milling and extraction activities have resulted in large amounts of waste rock deposits and U tailing materials placed in the vicinity of inhabited areas. To assess the environmental impact of radionuclides and trace metals in the Taboshar and Digmai mining and tailing sites in Tajikistan, field expeditions were performed in 2006 and 2008. In addition to in situ gamma and radon dose rate measurements, sampling of water, fish, sediments, soils and vegetation including in situ fractionation of water were performed. The U concentrations in water from Taboshar Pit Lake (2.0 mg U/L) were higher than in waters collected in the Digmai area. The Pit Lake and the stream water from the tailing mountain were also characterised by elevated concentrations of As, Mo, Mn and Fe, exceeding the WHO recommended values for drinking water. Uranium, As, Mo and Ni were present as low molecular mass species in the waters, and are therefore considered mobile and potentially bioavailable. The (238)U concentrations in sediments and soils varied between the sites; with peak concentrations (6 kBq/kg dw) in sediments from the Pit Lake, while the soil concentrations were significantly lower (296-590 Bq/kg dw). In contrast, high levels of the radium isotopes ((226)Ra and (228)Ra) were found in the Digmai soil (17-32 kBq/kg dw). Based on sequential extraction results, both U and Pb were found to be quite mobile at the Pit Lake site, showing that these elements were associated with the pH sensitive and redox sensitive amorphous fractions. In tailings, U was found to be quite mobile, but here Pb was rather inert. The transfer of radionuclides and metals from sediments to waters was in general low. In the Pit Lake, U was quite mobile (Kd = 90 L/kg), followed by Ni (1.5 × 10(3) L/kg) and As (6 × 10(3) L/kg), Cu and Cd (1.5 × 10(4) L/kg), while Pb (3 × 10(5) L/kg) was rather inert. The transfer from soil to plant, TFs (kg/kg dw), was in general low, while the bioconcentration factor for water living Poaceae and for fish from water was relatively high (Pb 1.8 × 10(5) and Cd 1 × 10(4)). These legacy sites, containing enhanced levels of natural radioactive material (TENORM) as well as heavy metals, may represent a hazard having a potential radiological and chemical impact on man and the environment, and measures should be taken to reduce the environmental risk to man and biota.

Exposure to radon in dwellings in the Sharri community, Kosovo.

Indoor air radon concentration was measured by exposing etched track detectors in the sleeping and living rooms of 18 houses in 6 villages of the Sharri community in Kosovo. Values ranged from 24 to 209 Bq m(-3), with only one exceeding 200 Bq m(-3), with a geometric mean and geometric standard deviation of 95.4 Bq m(-3) and 1.6, respectively. On the basis of the assumption that the spring radon concentrations obtained in this survey represent the yearly average, annual effective doses of residents were calculated; they range from 0.89 to 4.7 mSv y(-1), with the geometric mean and geometric standard deviation of 1.5 mSv y(-1) and 2.2, respectively. No mitigation measures are planned to be undertaken.

Exposure to radon in the Gadime Cave, Kosovo.

Air radon concentration was measured in summer and winter at 11 points along the tourist guided route in the Gadime Cave in Kosovo using alpha scintillation cells and etched track detectors. At two points in summer, values higher than 1700Bqm(-3) were observed; they otherwise were in the range 400-1000Bqm(-3). Values were lower in winter. The effective dose received by a person during a 90min visit is 3.7microSv in summer and 2.5microSv in winter. For a tourist guide the annual effective dose is less than 3.5mSv.

Mercury, selenium, and cadmium in human autopsy samples from Idrija residents and mercury mine workers.

Total Hg and Se concentrations were determined in autopsy samples of retired Idrija mercury mine workers, Idrija residents living in a Hg-contaminated environment, and a control group with no known Hg exposure from the environment. In selected samples we also checked the presence of MeHg. The highest Hg concentrations were found in endocrine glands and kidney cortex, regardless of the group. MeHg contributed only to a negligible degree to the total mercury concentrations in all analyzed samples. In the Hg-exposed groups the coaccumulation and retention of mercury and selenium was confirmed. Selenium coaccumulation with a Hg/Se molar ratio near 1 or higher was notable only in those tissue samples (thyroid, pituitary, kidney cortex, nucleus dentatus) where the mercury concentrations were >1 microg/g. After tissue separation of such samples the majority of these elements were found in the cell pellet. Because the general population is continuously exposed to Cd and possibly also to Pb from water, food, and/or air, in some samples the levels of these elements were also followed. In all examined control tissue samples the average values of Cd (kidney cortex, thyroid, hippocampus, cortex cerebellum, nucleus dentatus) and Pb (thyroid, hippocampus) exceeded the average values of Hg. Cd concentrations were the highest, particularly in kidney cortex and thyroids (microg/g), but no relationship between Cd and Se concentration was evident at the tissue level. Regarding the results in the control group, it is debatable which element is the more hazardous for the general population as concerns neurotoxicity.

The evaluation of waste, surface and ground water quality using the Allium test procedure.

The bulbs of Allium cepa were grown in test liquids of various pollution levels as follows: undiluted industrial and municipal waste water; biological treatment plant output water; water from the Drava river upstream and downstream of the city of Maribor; and non-chlorinated drinking water as a negative control test. The paper presents the response of the Allium cepa genetic material to the presence of potential cytotoxic and genotoxic substances in test liquids and the suitability of the Allium cepa testing procedure as a method for short-term determination of water pollution level. The suitability of the Allium test procedure as a system for environmental monitoring is presented. The influence of water pollution on macroscopic and cytologic parameters of the common onion by application of the biological testing method was examined. The macroscopic parameter was inhibition of root growth. The cytological parameters were: aberrant cells in metaphase and anaphase, index of micronuclei appearance and inhibition of cell division. The possibility of categorization the different polluted test liquids into quality classes is presented according to the influence of the test liquids on macroscopic and cytologic parameters. Test liquids are divided into 8 quality classes: the first class is the least polluted surface waters, the second and the third classes are more polluted surface water, the fourth and the fifth classes are biological treatment plant output waters, the sixth till the eighth quality classes are untreated waste waters. The most polluted test liquids (untreated industrial and municipal waste waters) caused sublethal and even lethal effects. The most polluted tested liquids cause the inhibition of root growth over 50% (even up to 74%), decrease of mitotic index over 36% (even up to 66%), increase of presence of interphase cells with micronuclei over 3% and increase of presence of aberrant cells for more than 10 times in comparison to control test.

Dietary mercury intake and human exposure in an Adriatic population.

A study was conducted to examine human exposure to mercury through dietary mercury intake in a population living in an industrially non-polluted area of the Adriatic Sea. The results have shown that approximately 20% of the subjects had a weekly dietary mercury intake above the provisional tolerable weekly intake (PTWI), primarily those consuming fish and other seafood > 6 times/week. The estimated seafood consumption corresponding to a mean intake of PTWI of 300 micrograms total mercury was 1559 g, and 1365 g for a PTWI of 200 micrograms methylmercury. However, the total mercury content in hair in individuals consuming total mercury above the PTWI was in the range of 1.3-12.9 micrograms/g, whereas the methylmercury content in hair in subjects consuming methylmercury above the PTWI was between 1.1-10.8 micrograms. Thus, the mercury content in hair did not reach the critical level at which toxic effects of mercury could be expected. The results, particularly those related to methylmercury exposure, did not differ significantly from data reported earlier from an industrially polluted area, thus indicating that the mercury content of fish and consequent human exposure to mercury reflects primarily the general ecological characteristics of the Adriatic, rather than the impact upon a specific local pollution.

Chromium-induced micronuclei in fish.

An investigation of the cytogenetic effects of chromium (Cr(VI) and Cr(III)) in Prussian carp (Carassius auratus gibelio) was made. For detecting cytogenetic damage, micronuclei induction in fish erythrocyte cells was employed. Fish were investigated 100 m above and 400 m below the discharge of leather waste products into the river Ljubljanica, and by exposing fish to three doses of chromium (Cr(VI) and Cr(III)) in the laboratory. The exposure of fish to various concentration levels (sub-lethal) of chromium under laboratory and field conditions caused an increase in the frequency of micronuclei compared with the control groups.

Systematic indoor radon and gamma measurements in kindergartens and play schools in Slovenia.

Systematic measurements of indoor radon concentrations and gamma dose rates were carried out in the 730 kindergartens and play schools in Slovenia that, together, care for 65,600 children. The main method for indoor radon measurement was direct sampling in alpha scintillation cells, but in cases with an increased instantaneous radon concentration, the additional methods of track-etch detectors and alpha spectroscopy were applied. In 528 kindergartens and play schools (72%), radon concentrations were below 100 Bq m-3, with a geometric mean of 58 Bq m-3. In 16 kindergartens and play schools (2.2%), radon concentrations exceeded 800 Bq m-3. In all cases, the main reason for a high indoor radon concentration was the geological structure of the soil. Gamma dose rates were measured with a portable scintillation counter, but in the Ljubljana region thermoluminescence dosimeters were also exposed. The results ranged from 30 to 295 nGy h-1, with a geometric mean of 88 nGy h-1.

Mercury toxicokinetics in Wistar rats exposed to elemental mercury vapour: modeling and computer simulation.

The kinetics of total mercury (Hg) absorption, distribution and elimination in Wistar rats exposed for long periods to elemental mercury vapour (Hg zero) in the Idrija mercury mine were studied. From the experimental data base a compartmental model was built as a framework for experimental data interpretation and prediction of organ mercury levels under different conditions. Using the model the exposures of rats under conditions comparable to those of professionally exposed workers (mercury miners, workers in the chloralkali industry) and individuals with amalgam fillings were simulated.

Interactions of mercury in rat brain.

In order to study the metabolism of mercury (Hg), its affinity to metallothionein (MT), and its influence on levels of the essential metals copper and zinc in the brain tissue of rats exposed to elemental mercury (HgO) vapor was investigated. The major findings were: 1. After long-term exposure, about 40% of mercury was found in the brain water-soluble phase (supernatant); 2. In brain supernatant, about 80% of Hg was found in the range of low-molecular-weight proteins; the MT-like protein Hg-Cu-Zn-thionein was isolated and partially characterized; 3. HgO vapor exposure resulted in increased tissue levels of essential Cu and Zn in addition to exogenous Hg; and 4. Experiments showed that HgO vapor exposure can induce the stimulation of rat brain MT synthesis.

Rapid radiochemical neutron activation analysis for iodine in urine by different separation techniques.

In the present work on radiochemical neutron activation analysis for the determination of iodine in urine samples, the performance of three different radiochemical separation techniques, namely, direct extraction, use of an iodinated ion-exchange resin column and Schöniger combustion, were intercompared and validated. The practical advantages of the iodinated-resin technique make it most suitable for the rapid routine determination of iodine in urine. It was further verified by participation in an international intercomparison run of urine analysis, and used in a pilot study on iodine determination in the urine of 171 Slovenian schoolchildren, where it gave results in good agreement with the catalytic method.

Investigation of mercury speciation in lichens.

Epiphytic lichens have long been considered to be reliable bioindicators of air pollution. In the present study only one lichen species, Hypogymnia physodes (L.) Nyl., was chosen; this species is very often used for biomonitoring in Europe. Total mercury and methylmercury were determined in lichens taken from various polluted and unpolluted locations in Slovenia, including a mercury mining area around Idrija. Additionally, total gaseous mercury in air was also determined at several sampling points.

A survey of lymphocyte chromosomal damage in Slovenian workers exposed to occupational clastogens.

Assays for sister-chromatid exchanges (SCE), unstable chromosome and chromatid aberrations and micronuclei were performed on blood lymphocytes from persons exposed protractedly to radiation or chemical hazards in the workplace. There was a general tendency with all endpoints examined for the yields to increase with years of working in the industry. This was especially marked for SCE. By comparison with a control group of administrative workers the levels of damage were higher, usually significantly so, in the occupational groups. These comprised workers at a nuclear research reactor, a hospital diagnostic X-ray department, a coal mine and a mercury ore mine.

Chromosome aberrations induced in human lymphocytes by U-235 fission neutrons: I. Irradiation of human blood samples in the "dry cell" of the TRIGA Mark II nuclear reactor.

A set-up for irradiation of biological samples in the TRIGA Mark II research reactor in Ljubljana is described. Threshold activation detectors were used for characterisation of the neutron flux, and the accompanying gamma dose was measured by TLDs. Human peripheral blood samples were irradiated "in vitro" and biological effects evaluated according to the unstable chromosomal aberrations induced. Biological effects of two types of cultivation of irradiated blood samples, the first immediately after irradiation and the second after 96 h storage, were studied. A significant difference in the incidence of chromosomal aberrations between these two types of samples was obtained, while our dose-response curve fitting coefficients alpha 1 = (7.71 +/- 0.09) x 10(-2) Gy-1 (immediate cultivation) and alpha 2 = (11.03 +/- 0.08) x 10(-2) Gy-1 (96 h delayed cultivation) are in both cases lower than could be found in the literature.

Determination of trace elements in standard reference materials by the ko-standardization method.

The ko-standardization method is suitable for routine multielement determinations by reactor neutron activation analysis (NAA). Investigation of NIST standard reference materials SRM 1571 Orchard Leaves, SRM 1572 Citrus Leaves, and SRM 1573 Tomato Leaves showed the systematic error of 12 certified elements determined to be less than 8%. Thirty-four elements were determined in NIST proposed SRM 1515 Apple Leaves.

Atmospheric radon concentrations in dwellings in Slovenia, Yugoslavia.

About 120 homes in Slovenia, Yugoslavia, were selected in urban areas, in a uranium rain and mill region, around coal-fired plants and around a phosphate mill. Radon-222 in air was determined using alpha scintillation cells and the gamma dose rate measured with thermoluminescent dosimeters. The levels obtained were explained by differences in building materials and ventilation rates of homes, as well as by the influence of man-made radioactivity sources. The results show that in the same region radon concentration, expressed as geometric mean, can be up to eight times higher in winter than in the autumn (Pohorje) or nine times higher in one region relative to another (Zirovski vrh-Zasavje).