ICRP Publication 114. Environmental protection: transfer parameters for reference animals and plants

Utilization of metal and radionuclide concentrations to assess the influence of shrimp farming on the geochemical characteristics of sediments

This article assesses the environmental impacts of aquatic biota cultivation, focusing on shrimp farming in Brazil's Northeast, as this practice has proven to be one of the main sources of economic growth in the region. For this purpose, sediment samples were collected from areas impacted and not directly impacted by shrimp farming, and concentrations of key geochemical parameters such as salinity, various elements (K, P, Cu, Mn, Pb, Zn, Al, Ca, Fe, Mg, and Na), and natural radionuclides (K-40, Ra-226 and Ra-228) were compared using statistical tools. Element concentrations were determined using ICP-OES, and naturally occurring radionuclide concentrations were obtained through gamma spectrometry. Statistical tests, such as ANOVA and/or Mann-Whitney, cluster analysis, and principal component analysis, were applied to the results. Additionally, the ERICA Tool software was employed to estimate deleterious effects on both human and non-human biota. Descriptive statistics reveal variability in sediment parameters around shrimp farming. ANOVA and Mann-Whitney tests compare concentrations of shrimp farm sediment and not directly impacted sediment, showing non-significant differences for most elements. pH and salinity, crucial for shrimp health, exhibit higher values in shrimp farm sediment. Alkali and alkaline earth metals, including K and Na, show no significant differences. Factor and cluster analyses suggest that certain elements, mainly radionuclides, are influenced by sediment variability. Hazard indices for naturally occurring radionuclides indicate negligible risk to both human and non-human biota, reinforcing the absence of adverse effects from shrimp farming activities. This study provides a comprehensive analysis of the environmental impacts of shrimp farming, emphasizing the importance of monitoring geochemical parameters for coastal environmental management.

Long-term radiological assessment of a Mediterranean freshwater ecosystem surrounding a nuclear power plant

The radionuclide concentration of man-made radionuclides on non-human biota in freshwater ecosystems has been extensively studied in environments affected by the Chernobyl and Fukushima accidents, in both humid continental and subtropical climates, respectively. However, there are very few studies that assess the long-term effects of operating nuclear facilities in Mediterranean environments. In the present study, a temporal analysis of the impact on carp, cattail, and bulrushes in the cooling pond of the currently operating Almaraz nuclear power plant was investigated for the period 2000-2020. The results do not show a general trend in man-made radionuclide concentrations. Instead, depending on their availability and the type of organism, trends decrease over time. This is also reflected in the effective half-lives obtained, which are lower than the physical half-life for some radionuclides. Transfer coefficients for the main man-made radionuclides detected were obtained, and it was found that these were significantly lower than the typical ranges found for benthic fish and vascular plants in freshwater ecosystems. Finally, the internal and external doses received by the carp have been evaluated using ERICA tool, and it has been observed that the main contribution to the total dose is due to the internal dose (0.65-7.04) × 10-4 µGy/h.

Internal dose rate due to intake of uranium and thorium by fish from a dam reservoir associated with a uranium mine in Brazil

Uranium mining can cause environmental impacts on non-human biota around mine sites. Because of this, the reduction in non-human biota exposure becomes an important issue. Environmental radioprotection results from the evolution of human radioprotection; it is based on dose rate to non-human biota and uses, as a biological target, and has harmful effects on populations. In the present study, a flooded impoundment created following dam construction in a uranium mine plant undergoing decommissioning was investigated. Internal dose rates due to activity concentration of natural uranium (Unat) and 232Th in omnivorous, phytophagous, and carnivorous fish species were estimated. Radionuclide activity concentrations were obtained by spectrophotometry with arsenazo III in the visible range. The dose rate contribution of 232Th was lower than that of Unat. There were no differences between the internal dose rates to studied fish species due to 232Th, but there were differences for Unat. A dose rate of 2.30·10-2 µGy∙d-1 was found due to the two studied radionuclides. Although this value falls below the benchmark for harmful effects, it is important to acknowledge that the assessment did not account for other critical radionuclides from uranium mining, which also contribute to the internal dose. Moreover, the study did not assess external doses. As a result, the possibility cannot be excluded that dose rates at the study area overcome the established benchmarks for harmful effects.

Assessment of dose rates to non-human biota from radioactive discharges from Sellafield Ltd. using PC-CREAM

PC-CREAM is a tool for assessing the radiological impact of routine discharges of radionuclides to the environment. It can be used for prospective assessments, to calculate doses to members of the public for authorisation of proposed discharges, or for retrospective assessments of previous discharges where doses are compared with dose limits. These types of assessment are a fundamental requirement of regulations governing the control of radioactive discharges. However, the latest publications of the basic safety standards for radiation protection, EU (Council of the European Union, 2014) and the IAEA (IAEA, 2014), now include the requirement to demonstrate protection of the environment as well as members of the public. To this end, a module has been added to PC-CREAM for calculating dose rates to non-human biota (Anderson et al., 2022). The methodology used for this calculation is based on the recommendations contained in ICRP Publication 108 (ICRP, 2008), which provides a general framework for protection of the environment. The additional module means that PC-CREAM can be used to assess doses to humans and dose rates to biota in an integrated way, for the same set of discharges and using the same dispersion models. This paper describes an assessment of dose rates to biota living in the vicinity of the Sellafield nuclear site, carried out using the new biota module of PC-CREAM. Historical discharges from Sellafield to the sea and atmosphere were considered for the period 1951 to 2017, excluding those from the Windscale fire in 1957. Dose rates calculated for marine biota (flatfish, crabs and brown seaweed) are less than 1 mGy d-1 and are below the lower derived consideration reference level (DCRL) for the ICRP marine reference animals and plants (RAPs). Dose rates for terrestrial biota (bees, deer, earthworms, frogs, wild grass, pine trees and rats) are less than the relevant lower DCRL for terrestrial RAPs, ie 0.1 mGy d-1. Dose rates were also calculated for a user defined organism 'seabird' to represent birds which inhabit both marine and terrestrial environments near Sellafield. For seabird, the lower DCRL of 0.1 mGy d-1 is exceeded throughout the 1950s, 1960s and 1970s, when the discharges were at their highest, due to exposures from the marine environment. Since the mid-1980s, no dose rates were calculated that exceeded the lower DCRLs.

90Sr and stable element levels in bones of brown bears: long-term trends in bear populations from Croatia and Poland

The aim of this study was to investigate the temporal trends and geographical differences in ⁹⁰Sr and stable element (Ba, Ca, Mn, Sr, Pb, Zn) levels in the bones of Croatian and Polish brown bear (Ursus arctos) populations. Experimental data suggest that in the decades after nuclear weapon tests and the Chernobyl accident, ⁹⁰Sr bone activity concentrations decreased from 352 to 11 Bq kg^-1 in the Croatian bear population (period 1982-2015) and from 831 to 27 Bq kg^-1 in Polish bears (period 1962-2020). Calculated effective and ecological half-lives were 9 and 13 years for Croatian bears, and 15 and 31 years for Polish bears, respectively. Different temporal trends were noted in levels of Ba, Mn, Pb and Zn between the two countries with majority of bones having lower Pb, Sr and Zn in Croatian than in Polish bears. Estimated values for the soil-to-bear transfer of ⁹⁰Sr were the same order of magnitude in the studied populations. Contrary to this, the estimated transfer of stable Sr was an order of magnitude lower for the Croatian bear population compared to Polish bears. The observed differences in soil-to-bear transfer between stable Sr and ⁹⁰Sr found for Croatian bears might suggest the need for careful consideration on the use of stable Sr data as an analogue for ⁹⁰Sr. To our knowledge, this is the first study that analysed ⁹⁰Sr activity in tissue of brown bears. As such, it provides insight into the fate and behaviour of one of the most relevant anthropogenic radionuclides at the top of the food chain.

Differential gene expression in chronically irradiated herbaceous species from the Chernobyl exclusion zone

PURPOSE

Transcriptional activity of genes related to ionizing radiation responses in chronically irradiated plant populations at radioactively contaminated territories can be a cost-effective and precise approach for stress response evaluation. However, there are limits to studying non-model plants in field conditions. The work studies the transcriptional activity of candidate genes of adaptation to chronic radiation exposure in plant populations from radioactively contaminated territories of the Chernobyl.

MATERIALS AND METHODS

In this work, we studied plant species with different sensitivity to acute irradiation: Trifolium repens L., Taraxacum officinale Wigg., and Dactylis glomerata L., sampled in the Chernobyl exclusion zone. The differential expression of several candidate genes of adaptation to chronic radiation exposure in the leaves of these species was analyzed, including homologs of Arabidopsis thaliana genes SLAC1, APX1, GPX2, CAB1, NTRB, PP2-B11, RBOH-F, HY5, SnRK2.4, PDS1, CIPK20, SIP1, PIP1, TIP1.

RESULTS AND CONCLUSIONS

All studied species were characterized by upregulation of the CAB1 homolog, encoding chlorophyll a/b binding protein, at radioactively contaminated plots. An increase in the expression of genes associated with water and hydrogen peroxide transport, intensity of photosynthesis, and stress responses (homolog of aquaporin TIP1 for T. repens; homologs of aquaporin PIP1 and transcription factor HY5 for D. glomerata; homolog of CBL-interacting serine/threonine protein kinase CIPK20 for T. officinale) was revealed. The methodological approach for studying gene expression in non-model plant species is described, which may allow large-scale screening studies of candidate genes in various plant species abundant in radioactively contaminated areas.

InterDosi Monte Carlo study of radiation exposure of a reference crab phantom due to radioactive wastewater deposited in marine environment following the Fukushima nuclear accident

S-values are typically used to quantify internal doses of biota internally due to the incorporation of radionuclides. In this study, the InterDosi 1.0 Monte Carlo code was used to estimate S-values in five main organs of a crab phantom as well as in surrounding seawater for eleven radionuclides, namely ³H, ¹⁴C, ¹³⁴Cs, ¹³⁷Cs, ⁶⁰Co, ¹²⁵Sb, ⁹⁰Sr, ¹²⁹I, ⁹⁹Tc, ¹⁰⁶Ru, and ²³⁸Pu. After the Fukushima accident, these radionuclides have been detected in wastewater by the Japan Nuclear Regulatory Authority. In this work, S-values were calculated for all crab organs and the surrounding seawater. These values can be used in conjunction with any measured activities in water, to determine internal doses absorbed by crab organs. Furthermore, it is shown that for a self-absorption condition the studied radionuclides can be classified into five main categories, with ²³⁸Pu showing the highest S-values for any organ. Moreover, the results demonstrate that the obtained S-values decrease with increasing organ mass. In contrast, for a cross-absorption condition, the studied organs can be classified into seven main categories. In addition, by taking seawater as a source of irradiation, ²³⁸Pu had the highest cross-absorption S-values in two organs of particular biological relevance, the heart and gonads, when compared to the remaining radionuclides. It is concluded that due to the pre-calculated S-value database of a reference crab, it will become easier to use this organism as a bio indicator to study any radiation-induced effects on the marine environment.

Dose Rate Assessment Exercises with Stylized Phantom of Neon Flying Squid from Northwest Pacific

Radiation protection for non-human marine organisms still faces many challenges. To establish a more realistic radiation dosimetry model of cephalopods, this study developed a stylized phantom of neon flying squid (Ommastrephesbartramii) containing ten organs and tissues based on magnetic resonance imaging (MRI) technology. The internal and external dose conversion coefficients for eight radionuclides (134Cs, 137Cs, 131I, 110mAg, 60Co, 54Mn, 65Zn, 95Zr) of each organ/tissue were determined with Monte Carlo simulation using the Geant4 toolkit. Furthermore, with the reported coastal seawater radioactivity levels at the coastal area of Fukushima Daiichi Nuclear Power Plant after the accident in 2011 as the source term, the radiological dose rate for O. bartramii was evaluated with the stylized phantom developed in this study and with the conventional whole-organism ellipsoidal model in the ERICA Assessment Tool. Both results showed that the dose rate for O. bartramii derived from the FDNPP accident releases exceeded the generic no-effects screening benchmark level (10 μGy h−1).

Bounding uncertainties around the conceptual representation of species in radiological assessment in the context of routine atmospheric release

Wildlife protection has become of regulatory interest since the International Commission on Radiological Protection (ICRP) developed an approach to assess the level of radiological protection specifically for animals and plants. For the purpose of demonstrating compliance with regulation to protect the environment against routine authorised discharges from nuclear facilities, the wide variety of biota inhabiting an ecosystem needs to be condensed to a limited set of representative organisms, as proposed by the ICRP with a set of 'reference animals and plants' which can be considered representative of many other species. It is now recommended in the International Atomic Energy Agency Safety Standards, and internationally accepted, that the use of such a limited number of organisms to represent a pool of species is adequate for radiation protection purposes, particularly in planned exposure situations. Adding site-specific species to that set of surrogate species can respond to various interests, such as ensuring a site-specific context to the assessment that addresses stakeholder interests and can aid in stakeholder consultation and risk communication. Moreover, there is a need to question whether the use of the set of surrogate organisms is conservative enough to cover a wider range of biodiversity. Previous studies partially answered this question and this paper adds a range of test cases. A selection of hypothetical representations of possible site-specific species are assessed on the basis of possible variations in size (mass) and occupancy habits. Dose rates are evaluated to determine the greatest difference between hypothetical organisms and those for reference organisms (ROs), considering radionuclides (RNs) potentially discharged in atmospheric routine release from different nuclear facilities. Differences observed in the results between hypothetical organisms and ROs were less than one order of magnitude in all cases, the difference being dependent on the RNs considered. These findings do not preclude the inclusion of site-specific species in environmental radiological assessments if it is considered necessary, but they provide reassurance that using ROs for radiological impact assessments in the case of routine atmospheric discharges is sufficient.

Quality management in radiotherapy treatment delivery

Radiation Oncology continues to rely on accurate delivery of radiation, in particular where patients can benefit from more modulated and hypofractioned treatments that can deliver higher dose to the target while optimising dose to normal structures. These deliveries are more complex, and the treatment units are more computerised, leading to a re-evaluation of quality assurance (QA) to test a larger range of options with more stringent criteria without becoming too time and resource consuming. This review explores how modern approaches of risk management and automation can be used to develop and maintain an effective and efficient QA programme. It considers various tools to control and guide radiation delivery including image guidance and motion management. Links with typical maintenance and repair activities are discussed, as well as patient-specific quality control activities. It is demonstrated that a quality management programme applied to treatment delivery can have an impact on individual patients but also on the quality of treatment techniques and future planning. Developing and customising a QA programme for treatment delivery is an important part of radiotherapy. Using modern multidisciplinary approaches can make this also a useful tool for department management.

Areas of research to support the system of radiological protection

This document presents the ICRP's updated vision on "Areas of Research to Support the System of Radiological Protection", which have been previously published in 2017. It aims to complement the research priorities promoted by other relevant international organisations, with the specificity of placing them in the perspective of the evolution of the System of Radiological Protection. This document contributes to the process launched by ICRP to review and revise the System of Radiological Protection that will update the 2007 General Recommendations in ICRP Publication 103.

Determination and mapping of the spatial distribution of cesium-137 in the terrestrial environment of Greece, over a period of 28 years (1998 to 2015)

In this study, we are applying the GIS techniques in order to record the data that have been collected for cesium-137, over the for the period 1998 to 2015, for the terrestrial environment in Greece. Following the Chernobyl Nuclear Power Plant (CNPP) accident in 1986, extended fieldwork was conducted for the determination of cesium-137 concentrations in the terrestrial environment. In 2011, in the light of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, new campaigns were organized in order to assess the variation in cesium-137 activity concentrations. The measured data, combined with data taken from the databases of the Environmental Radioactivity Laboratory (NCSR'Demokritos', in Athens, Greece), as well as, from the European Atlas of Cesium Deposition on Europe, are being used for the spatial distribution analysis of cesium-137 in the country. Furthermore, are used for the temporal analysis of this radionuclide in a long-term basis. Moreover, we are using the ERICA Assessment Tool for the calculation of the dose rate that the studied organisms (plants of Poaceae spp. and mammals of Bovidae spp.) receive due to the exposure to cesium-137. All gathered information provides us with thematic maps, designed through the GIS techniques, that allow for an appropriate representation of cesium-137 presence in the country nowadays. This study provides an insightful view of the behavior of this anthropogenic radionuclide that is useful for future research in order to elucidate its behavior in long-term periods. The knowledge of the environmental fate of radionuclides is important because it contributes to the projection of long-term risks resulting from radionuclide releases, as well as, for the selection of cost-effective remediation strategies. Furthermore, it provides the opportunity to conduct a comprehensive risk assessment in the region, as the studied organisms were exposed to low-level ionizing radiation. But, as it was shown, on the level of ecosystem, no significant impact was estimated. However, regarding the future objectives, further consideration of the exposure levels should be considered while taking also into account the exposure to natural and background radiation and the exposure to spontaneous emission of anthropogenic radionuclides, especially if we want to consider the eventual effects of protracted low-level ionising radiation on the various levels of life's organization.

Distribution and transfer of naturally occurring radionuclides and 137Cs in the freshwater system of the Plitvice Lakes, Croatia, and related dose assessment to wildlife by ERICA Tool

The aim of this study was to investigate the natural radioactivity of Plitvice Lakes, under the assumption that due to its status as a National Park, the area can be considered an example of a natural freshwater system. Also, considering the transfer parameter data as the largest source of uncertainty in radiological risk assessments, the impact of site-specific data on dose rate assessment, as opposed to currently available data, was investigated. The study included gamma and alpha spectrometric measurements of ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²²⁸Ra, and ⁴⁰K in water, sediment, and fish samples, as well as ¹³⁷Cs due to the coinciding of the study with the Fukushima accident. The content of naturally occurring radionuclides significantly varied in sediments of different Lakes, probably as a reflection of the different underlying geology of the area. Also, the ²¹⁰Pb distribution in sediments indicated an up to 312 Bq kg^-1 of the allochthonous contribution of this radionuclide at the beginning of the Lake's watercourse, which probably entered into the lake system by the major inlet river with its steady decrease along downstream lakes. Low ⁴⁰K activity concentrations (27.5 ± 20.1 mBq L^-1) in the Lake's waters might be one of the causes of increased ¹³⁷Cs activity concentrations in fish samples (1.5 ± 0.4 Bq kg^-1), which was found to be an order of magnitude higher than average values for different fish species from other Croatian freshwater systems (0.2 ± 0.1 Bq kg^-1). A temporary increase of ¹³⁷Cs activity concentrations was measured in water samples collected immediately after the Fukushima accident. Calculated site-specific sediment/water distribution coefficients and fish/water concentration ratios for radium and caesium were on average lower than generic ones found in the literature. Background dose rate assessments performed by the ERICA Tool indicated a profound impact of different input data on assessment results with water activity concentrations resulting in significantly higher dose rates (0.1-67 μGy h^-1) in comparison to sediment activity concentrations (0.03-9 μGy h^-1). An incremental dose rate due to ¹³⁷Cs was found to be in the range of < 0.001-0.023 μGy h^-1 which, in comparison to background dose rates, can be considered negligible.

Evaluation of uncertainties in environmental impact assessment of naturally occurring radiation exposure situations on example of undisturbed and legacy NORM sites in the Fen Complex, Norway

The risk from naturally occurring radioactive materials (NORM) has been extensively assessed, and this has led to the integration of specific NORM radiation protection requirements within the latest EU Directive 2013/59. Nevertheless, it has been internationally recognised that remaining NORM knowledge gaps and uncertainties now present similarly significant issues in addressing recent regulatory requirements. The multi-tiered nature of environmental impact assessment (EIA) implies per se possibility for uncertainties, but when EIA at radiation exposure sites includes consideration of sites with multiple radiation and contamination sources, different ecosystem transport pathways, effects and risks by applying different parameters and models, level of overall uncertainty increases. The results of EIA study in the Fen area in Norway, comprised of undisturbed and legacy NORM sites, have been evaluated in this analysis, in order to identify all existing input uncertainties and how they may impact the final conclusions, and thus, influence any subsequent decision-making. The main uncertainties have been identified in the measurement and exposure analysis tier, and were related to the heterogeneous distribution of radionuclides, radionuclide speciation, as well as to generic variability issues in the concepts used for mobility and biota uptake analysis (such as distribution coefficient, transfer factors and concentration ratios) as well as radioecological modelling. The uncertainties in the input values to the calculation of the dose arising from radon exposure in the Fen area led to an overall elevated uncertainty of the magnitude of the radiation exposure dose of humans. It has been concluded that an integrated, ecosystem-based approach with consideration of complexity of prevailing environmental conditions and interconnections must be applied to fully understand possible radiation effects and risks.

Transforming Acute Ecotoxicity Data into Chronic Data: A Statistical Method to Better Inform the Radiological Risk for Nonhuman Species

Ecotoxicity data constitute the basic information to support the derivation of ecological benchmark values, whatever the stressor concerned. However, the set of appropriate data may be limited, especially with regard to chronic exposure conditions. The available data are often biased in favor of acute data from laboratory-controlled conditions, much easier to acquire. To make the best use of the available knowledge and better inform the effects of ionizing radiation chronic exposure on nonhuman species, we investigated the transposition to ionizing radiation ecotoxicity of one method proposed for chemicals to extrapolate chronic information from acute toxicity data. Such a method would contribute to enriching chronic data sets required for the derivation of benchmark values, making them more robust when used as reference values for ecological risk assessment. We developed accordingly the Acute to Chronic Transformation for Radiotoxicity data (ACTR) approach, which we validated. We introduced then the new concept of Endpoint Sensitivity Distribution (ESD). This finally allowed us to compare purely chronic and ACTR-built ESDs for different taxa. For some of them, the predicted and observed distributions looked very similar. This promising ACTR method appeared applicable with a reasonable level of confidence, but its generalization asks for improvements, some being already identified.

Characterization of radioactive particles from the Dounreay nuclear reprocessing facility

Radioactive particles originating from nuclear fuel reprocessing at the United Kingdom Atomic Energy Authority's Dounreay Facility were inadvertently released to the environment in the late 1950s to 1970s and have subsequently been found on site grounds and local beaches. Previous assessments of risk associated with encountering a particle have been based on conservative assumptions related to particle composition and speciation. To reduce uncertainties associated with environmental impact assessments from Dounreay particles, further characterization is relevant. Results of particles available for this study showed variation between Dounreay Fast Reactor (DFR) and Materials Test Reactor (MTR) particles, reflecting differences in fuel design, release scenarios, and subsequent environmental influence. Analyses of DFR particles showed they are small (100-300 μm) and contain spatially correlated U and Nb. Molybdenum, part of the DFR fuel, was identified at atomic concentrations below 1%. Based on SR-based micrometer-scale X-ray Absorption Near Edge Structure spectroscopy (μ-XANES), U may be present as U(IV), and, based on a measured Nb/U atom ratio of ~2, stoichiometric considerations are commensurable with the presence of UNb₂O₇. The MTR particles were larger (740-2000 μm) and contained U and Al inhomogeneously distributed. Neodymium (Nd) was identified in atomic concentrations of around 1-2%, suggesting it was part of the fuel design. The presence of U(IV) in MTR particles, as indicated by μ-XANES analysis, may be related to oxidation of particle surfaces, as could be expected due to corrosion of UAl_x fuel particles in air. High ²³⁵U/²³⁸U atom ratios in individual DFR (3.2 ± 0.8) and MTR (2.6 ± 0.4) particles reflected the presence of highly enriched uranium. The DFR particles featured lower ¹³⁷Cs activity levels (2.00-9.58 kBq/particle) than the MTR (43.2-641 kBq ¹³⁷Cs/particle) particles. The activities of the dose contributing radionuclides ⁹⁰Sr/⁹⁰Y were proportional to ¹³⁷Cs (⁹⁰Sr/¹³⁷Cs activity ratio ≈ 0.8) and particle activities were roughly proportional to the size. Based on direct beta measurements, gamma spectrometry, and the VARSKIN6 model, contact dose rates were calculated to be approximately 74 mGy/h for the highest activity MTR particle, in agreement with previously published estimates.

Baseline radioecological data for the soil and selected bioindicator organisms in the temperate forest of Plitvice Lakes National Park, Croatia

The aim of this study was to provide baseline radioecological data for the temperate forest ecosystem in Plitvice Lakes National Park. Emphasis was placed on the determination of naturally occurring radionuclides since there is an acknowledged lack of data for these radionuclides in non-accident conditions in wildlife, even for bioindicator organisms. Activity concentrations of ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²³²Th, ⁴⁰K, ¹³⁴Cs, and ¹³⁷Cs were measured by gamma spectrometry in soil and bioindicators: earthworms, conifer needles, mosses, and lichens. From the measured activity concentrations, concentration ratios were calculated to quantify the transfer of these radionuclides from soil to bioindicators. Our results show that soil activity concentrations are biased toward results from other studies conducted within the Dinaric mountain region. However, in moss and lichen samples, we measured higher activity concentrations of ²²⁶Ra and lower activity concentrations of ⁴⁰K and ¹³⁷Cs in comparison to similar studies. Also, we estimated lower concentration ratios for all radionuclides from soil to these organisms, except for ²¹⁰Pb, in comparison to generic values. The transfer of ²³⁸U was generally low for all of the bioindicator organisms. For conifer needles, a correlation was found between activity concentrations of ²²⁶Ra and ¹³⁷Cs in soil and related concentration ratios. Correlation was also found between the activity concentration of ⁴⁰K in soil and transfer of ⁴⁰K and ¹³⁷Cs to mosses and lichens. A comparison with literature data highlighted the lack of ²²⁶Ra related concentration ratios for conifer trees and especially for earthworms. Therefore, the results of this study could supplement the sparse data currently available on radionuclide background data in similar ecosystems and related soil-to-wildlife transfer of radionuclides. Dose rate assessments, performed by the ERICA Tool, estimated that 96% of the overall exposure of wildlife in the Park area is due to the background dose rates, while 0.06 μGy h^-1 on average can be attributed as an incremental dose rate from ¹³⁴Cs and ¹³⁷Cs.

Radiological risk assessment in the terrestrial ecosystem: comparative study of two software tools used for dose rate calculations

In this study, two software tools, namely the ERICA Assessment Tool and the RESRAD-BIOTA code, are used for the calculation of the radiological exposure of non-human organisms. For the purposes of the analysis, data retrieved from field studies are used. The site-specific measurements were performed on organisms (mammals-sheep and goats of Bovidae spp.) collected from free-ranged grazing regions in Greece. Plants (grass) of Poaceae spp. and soil samples were also collected from these regions. Natural radionuclides (²²⁶Ra, ²²⁸Ra, and ²²⁸Th) of lithogenic origin and ¹³⁷Cs, resulted from human activities (Chernobyl and Fukushima nuclear power plant accidents and global fallout), were detected in all samples. The measured activity concentrations were used as input to the two software tools, the ERICA Assessment Tool and the RESRAD-BIOTA code. The results of the simulations provided the external, internal, and total dose rates received by the organisms due to the exposure to the radionuclides. The assessments indicated that out of all detected radionuclides, ²²⁸Th is the main contributor to the external dose and ²²⁶Ra and ²²⁸Ra are the main contributors to the internal dose. The comparative analysis of the two tools revealed significant differences in the calculated doses. In fact, external and internal doses calculated by RESRAD-BIOTA are higher than the values calculated by the ERICA Tool, due to the dose conversion coefficients (DCCs) used for the dose calculation. RESRAD-BIOTA provides more conservative values, but ERICA Tool provides lower uncertainty due to the higher flexibility in the design of the phantom organism. On a risk assessment basis, there is no significant impact, due to organisms' exposure to radioactivity. However, further consideration of the exposure levels is required due to the potential effects of protracted low-level ionizing radiation on the various levels of life's organization.

ESTE ANNUAL IMPACTS-SYSTEM FOR ASSESSMENT OF RADIOLOGICAL IMPACTS OF OPERATIONAL DISCHARGES FROM NUCLEAR FACILITIES

Described are models and approaches of the software tool ESTE Annual Impacts, a system for analyzes of radiological impacts of operational discharges to the atmosphere and hydrosphere from nuclear facilities. As a result, evaluated are radiological impacts to the population (to representative person and collective doses) and the environment (plants and animals). Described are models applied for calculation of dispersion in the atmosphere and hydrosphere (river, dam, sea). Method of application of sea currents for dispersion calculation in marine environment is also presented. The system is used by operators of the operated and decommissioned nuclear facilities at the site Bohunice (Slovakia), by regulatory authority of the Czech Republic for facilities at the sites Dukovany and Temelín and by operator of the Bushehr Nuclear Power Plant (Iran). In addition, the system is tool for analyses of environmental impacts assessments, applied in environmental impacts assessments process for newly prepared nuclear sources in Slovakia and Czech Republic.

Concentration of 210Po and 210Pb in macroalgae from the northern Gulf

This baseline study highlights the 210Po and 210Pb concentration in seven macroalgae species from the northern Gulf that are frequently washed ashore during the bloom season from February to April. The highest concentrations of 210Po and 210Pb were 2.947 ± 0.032 and 1.057 ± 0.145 Bq kg-1 wwt, respectively, in brown algae Sargassum boveanum, and the lowest in green algae Ulva prolifera with 1.533 ± 0.058 and 0.170 ± 0.069 Bq kg-1 wwt, respectively. A 210Po enrichment was observed in both brown and green algae species, with the 210Po/210Pb ratio being >1 for all the samples. The mean concentration of 210Po in all species was an order of magnitude higher than 210Pb, and the difference in mean concentration is statistically significant (p < 0.001). At the same time, the mean concentration of dissolved 210Po and 210Pb in seawater was 0.28 ± 0.01 and 0.52 ± 0.01Bq m-3 with a 210Po/210Pb ratio of 0.54 ± 0.02 indicating that 210Po was absorbed from water and more concentrated by macroalgae. The measured concentration factor (CF) for 210Po in these macroalgae for the northern Gulf varied between 5 × 103-1 × 104, higher than the IAEA recommended value of 1 × 103 which suggests that a revision of that value may be needed. The field derived CFs for 210Pb vary between 3 × 102-1.8 × 103, comparable to the ICRP recommended value of 2 × 103.

Variation in chronic radiation exposure does not drive life history divergence among Daphnia populations across the Chernobyl Exclusion Zone

Ionizing radiation is a mutagen with known negative impacts on individual fitness. However, much less is known about how these individual fitness effects translate into population-level variation in natural environments that have experienced varying levels of radiation exposure. In this study, we sampled genotypes of the freshwater crustacean, Daphnia pulex, from the eight inhabited lakes across the Chernobyl Exclusion Zone (CEZ). Each lake has experienced very different levels of chronic radiation exposure since a nuclear power reactor exploded there over thirty years ago. The sampled Daphnia genotypes represent genetic snapshots of current populations and allowed us to examine fitness-related traits under controlled laboratory conditions at UK background dose rates. We found that whilst there was variation in survival and schedules of reproduction among populations, there was no compelling evidence that this was driven by variation in exposure to radiation. Previous studies have shown that controlled exposure to radiation at dose rates included in the range measured in the current study reduce survival, or fecundity, or both. One limitation of this study is the lack of available sites at high dose rates, and future work could test life history variation in various organisms at other high radiation areas. Our results are nevertheless consistent with the idea that other ecological factors, for example competition, predation or parasitism, are likely to play a much bigger role in driving variation among populations than exposure to the high radiation dose rates found in the CEZ. These findings clearly demonstrate that it is important to examine the potential negative effects of radiation across wild populations that are subject to many and varied selection pressures as a result of complex ecological interactions.

Radiocaesium transfer and radiation exposure of frogs in Fukushima Prefecture

The International Commission on Radiological Protection has proposed an environmental assessment framework. This includes ionising radiation exposure assessment for different frog life-stages, but radiocaesium transfer parameters are unavailable. We collate data from the Fukushima Prefecture (contaminated by the Fukushima accident) and estimate radiocaesium concentration ratio (CRwo-water) values for tadpoles and adult frogs, presenting the largest available amphibian CRwo-water dataset. In total, 513 adult frogs and 2540 tadpoles were analysed in 62 and 59 composite samples respectively. Results suggest that equilibrium was reached between water and amphibian radiocaesium activity concentrations circa one-year after the accident. Radiocaesium transfer to tadpoles was higher than to adult frogs. Dose rates were estimated for different life-stages and species in both the aquatic and terrestrial environment. Estimated dose rates to adults and tadpoles were typically similar because external exposure dominated for both organisms; frogspawn dose rates were estimated to be orders of magnitude lower than other life-stages. For the two sites assessed, which were outside of the most contaminated areas of the Fukushima Prefecture, estimated dose rates were below those anticipated to present a risk to wildlife populations; it is likely that dose rates in more contaminated areas were in excess of some effects benchmark values.

Calculating the radiological parameters used in non-human biota dose assessment tools using ERICA Tool and site-specific data

The substantial complexity in ecosystem-radionuclide interactions is difficult to be represented in terms of radiological doses. Thus, radiological dose assessment tools use typical exposure situations for generalized organisms and ecosystems. In the present study, site-specific data and radioactivity measurements of terrestrial organisms (grass and herbivore mammals) and abiotic components (soil) are provided. The retrieved data are used in combination with the ERICA Assessment Tool for calculation of radiological parameters. The process of radionuclide transfer within ecosystem components is represented using concentration ratios (CRs), while for the calculation of dose rates the dose conversion coefficient (DCC) methodology is applied. Comparative assessments are performed between the generic and assessment-specific radiological parameters and between the resulting dose rates. Significant differences were observed between CRs calculated in this study and those reported in the literature for cesium and thorium, which can easily be explained. On the other hand, CRs calculated for radium are in very good agreement with those reported in the literature. The DCCs exhibited some small differences between the reference and the assessment-specific organism due to mass differences. The differences were observed for internal and external dose rates, but they were less pronounced for total dose rates which are typically used in the assessment of radiological impact. The results of the current work can serve as a basis for further studies of the radiological parameters in environments that have not been studied yet.

A biokinetic and dosimetric model for ionic indium in humans

This paper reviews biokinetic data for ionic indium, and proposes a biokinetic model for systemic indium in adult humans. The development of parameter values focuses on human data and indium in the form of ionic indium(III), as indium chloride and indium arsenide. The model presented for systemic indium is defined by five different pools: plasma, bone marrow, liver, kidneys and other soft tissues. The model is based on two subsystems: one corresponding to indium bound to transferrin and one where indium is transported back to the plasma, binds to red blood cell transferrin and is then excreted through the kidneys to the urinary bladder. Absorbed doses to several organs and the effective dose are calculated for ¹¹¹In- and ^113mIn-ions. The proposed biokinetic model is compared with previously published biokinetic indium models published by the ICRP. The absorbed doses are calculated using the ICRP/ICRU adult reference phantoms and the effective dose is estimated according to ICRP Publication 103. The effective doses for ¹¹¹In and ^113mIn are 0.25 mSv MBq^-1 and 0.013 mSv MBq^-1 respectively. The updated biokinetic and dosimetric models presented in this paper take into account human data and new animal data, which represent more detailed and presumably more accurate dosimetric data than that underlying previous models for indium.

Establishment of the Detailed Breast Model of Chinese Adult Female and Application in External Radiation Protection

Breast is one of the most sensitive organs to radiation. In 2007, International Commission on Radiological Protection (ICRP) increased the tissue weighting factor for the breast from 0.05 to 0.12, which made the accurate evaluation of breast dose more important. But in the existing human voxel phantom, the structure of breast is not elaborate enough because of the limitation of image resolution used for phantom modeling. This will probably affect the accuracy of breast dose calculated in simulation. Some researches on detailed breast modeling have been carried out, but there is no such research in this field in China. A detailed breast model for Chinese adult female is established in this article using the mathematical modeling method. It is voxelized and merged with the Chinese reference adult female voxel model for breast dosimetry. Dose conversion coefficients of breast gland for external photon exposures in antero-posterior geometry are calculated as an example of the application and the results are compared with those calculated by the old voxel phantom and ICRP reference adult female voxel phantom.

Radioactive contamination of arthropods from different trophic levels in hilly and mountainous areas after the Fukushima Daiichi nuclear power plant accident

In order to understand the influence of the Fukushima Daiichi nuclear power plant accident on the ecosystem in hilly and mountainous areas of Fukushima Prefecture, chronological changes in the levels of radiocesium in arthropod species were investigated. From 2012 to 2014, arthropods from different trophic levels were sampled and the air radiation dose rates at the sampling sites were analyzed. The air radiation dose rates showed a significant and constant reduction over the 2 years at the sampling sites in Fukushima. The median radiocesium concentration (¹³⁴Cs + ¹³⁷Cs) detected in the rice grasshopper, Oxya yezoensis, and the Emma field cricket, Teleogryllus emma, dropped continuously to 0.080 and 0.078 Bq/g fresh weight, respectively, in 2014. In contrast, no significant reduction in radioactive contamination was observed in the Jorô spider, Nephila clavata, in which the level remained at 0.204 Bq/g in 2014. A significant positive correlation between radiocesium concentration and the air radiation dose rate was observed in the rice grasshopper, the Emma field cricket and the Jorô spider. The highest correlation coefficient (ρ = 0.946) was measured in the grasshopper.

BASIC RADIATION PROTECTION EDUCATION AND TRAINING FOR MEDICAL PROFESSIONALS; GEORGIAN EXPERIENCE AND FUTURE PERSPECTIVE

The level of knowledge provided by the Tbilisi State Medical University (TSMU) standard curriculum modules in 'Medical physics' and 'Radiation risk estimates' was assessed as was the learning outcome of modern standards elective course in 'Radiation protection'. Two groups of medical students were examined: Group 1: 5 y students, participants in elective course 'Radiobiology and radiogenic health risk' and Group 2: 1-2 y students, participants in winter and summer schools. Students were tested before and after training courses with the same tests questionnaire. The results of the tests showed the necessity for improvement of the educational curriculum. The changes needed are the inclusion of a basic radiobiological course in the curricula of the faculty of medicine and expansion of the medical physics course through a more detailed presentation of medical imaging methods.

Radiological protection and the exposure of animals as patients in veterinary medicine

It is apparent that most of the techniques that make use of ionising radiation in human medical practices are now being applied in veterinary medicine. Steps are being taken by the IAEA to provide guidance for humans involved in such practices, but there appears to be no international initiative that considers the protection or welfare of the animal as a patient. There is therefore a risk that the deliberate exposure of an animal, particularly in the therapeutic application of radiation, could do more harm than good. In the light of recent developments in dosimetric modelling and the application of known effects of radiation on different types of animals, for the purposes of the protection of biota in an environmental context, it is argued that it would be sensible now to start a serious consideration of this issue. Some suggestions are made with regard to a number of areas that could be considered further, both specifically and with regard to the field of radiological protection as a whole.

Radiation Dosimetry of Whole-Body Dual-Tracer 18F-FDG and 11C-Acetate PET/CT for Hepatocellular Carcinoma

Combined whole-body dual-tracer ((18)F-FDG and (11)C-acetate) PET/CT is increasingly used for staging hepatocellular carcinoma, with only limited studies investigating the radiation dosimetry data of these scans. The aim of the study was to characterize the radiation dosimetry of combined whole-body dual-tracer PET/CT protocols.

METHODS

Consecutive adult patients with hepatocellular carcinoma who underwent whole-body dual-tracer PET/CT scans were retrospectively reviewed with institutional review board approval. OLINDA/EXM 1.1 was used to estimate patient-specific internal dose exposure in each organ. Biokinetic models for (18)F-FDG and (11)C-acetate as provided by ICRP (International Commission on Radiological Protection) publication 106 were used. Standard reference phantoms were modified to more closely represent patient-specific organ mass. With patient-specific parameters, organ equivalent doses from each CT series were estimated using VirtualDose. Dosimetry capabilities for tube current modulation protocols were applied by integrating with the latest anatomic realistic models. Effective dose was calculated using ICRP publication 103 tissue-weighting coefficients for adult male and female, respectively.

RESULTS

Fourteen scans were evaluated (12 men, 2 women; mean age ± SD, 60 ± 19.48 y). The patient-specific effective dose from (18)F-FDG and (11)C-acetate was 6.08 ± 1.49 and 1.56 ± 0.47 mSv, respectively, for male patients and 6.62 ± 1.38 and 1.79 ± 0.12 mSV, respectively, for female patients. The patient-specific effective dose of the CT component, which comprised 2 noncontrast whole-body scans, to male and female patients was 21.20 ± 8.94 and 14.79 ± 3.35 mSv, respectively. Thus, the total effective doses of the combined whole-body dual-tracer PET/CT studies for male and female patients were 28.84 ± 10.18 and 23.19 ± 4.61 mSv, respectively.

CONCLUSION

Patient-specific parameters allow for more accurate estimation of organ equivalent doses. Considering the substantial radiation dose incurred, judicious medical justification is required with every whole-body dual-tracer PET/CT referral. Although radiation risks may have less impact for the population with cancer because of their reduced life expectancy, the information is of interest and relevant for both justification, to evaluate risk/benefit, and protocol optimization.

Radioactivity measurements and dose rate calculations using ERICA tool in the terrestrial environment of Greece

In the present study, the radioactivity levels to which terrestrial non-human biota were exposed are examined. Organisms (grass and herbivore mammals) and abiotic components (soil) were collected during the period of 2010 to 2014 from grasslands where sheep and goats were free-range grazing. Natural background radionuclides ((226)Ra, (228)Ra, (228)Th) and artificial radionuclides ((137)Cs, (134)Cs, (131)I) were detected in the collected samples using gamma spectrometry. The actual measured activity concentrations and site-specific data of the studied organisms were imported in ERICA Assessment Tool (version 1.2.0) in order to provide an insight of the radiological dose rates. The highest activity concentrations were detected in samples collected from Lesvos island and the lowest in samples collected from Attiki and Etoloakarnania prefectures. The highest contribution to the total dose rate was clearly derived from the internal exposure and is closely related to the exposure to alpha emitters of natural background ((226)Ra and (228)Th). The Fukushima-derived traces of (137)Cs, (134)Cs, and (131)I, along with the residual (137)Cs, resulted in quite low contribution to the total dose rate. The obtained results may strengthen the adaptation of software tools to a wider range of ecosystems and may be proved useful in further research regarding the possible impact of protracted low level ionizing radiation on non-human biota. This kind of studies may contribute to the effective incorporation of dosimetry tools in the development of integrated environmental and radiological impact assessment policies.

Radionuclide biological half-life values for terrestrial and aquatic wildlife

The equilibrium concentration ratio is typically the parameter used to estimate organism activity concentrations within wildlife dose assessment tools. Whilst this is assumed to be fit for purpose, there are scenarios such as accidental or irregular, fluctuating, releases from licensed facilities when this might not be the case. In such circumstances, the concentration ratio approach may under- or over-estimate radiation exposure depending upon the time since the release. To carrying out assessments for such releases, a dynamic approach is needed. The simplest and most practical option is representing the uptake and turnover processes by first-order kinetics, for which organism- and element-specific biological half-life data are required. In this paper we describe the development of a freely available international database of radionuclide biological half-life values. The database includes 1907 entries for terrestrial, freshwater, riparian and marine organisms. Biological half-life values are reported for 52 elements across a range of wildlife groups (marine = 9, freshwater = 10, terrestrial = 7 and riparian = 3 groups). Potential applications and limitations of the database are discussed.

Basis for standards: ICRP activities

The purpose of this chapter is to describe work achieved recently by the International Commission on Radiological Protection (ICRP) and especially by Committee 3 (Protection in Medicine) and its use for standards. In March 1960, the Board of Governors of the International Atomic Energy Agency approved the Agency's 'Health and Safety Measures', stating that the Agency's 'Basic Safety Standards' (BSS) would be based, to the extent possible, on the recommendations of the ICRP. In a similar way, the Council of the European Union took into account the new recommendations of the ICRP when adopting the new Directive 2013/59/EURATOM that laid down BSS for protection against the dangers arising from exposure to ionising radiation. The new limit for the lens of the eyes for occupational exposures has been incorporated into these international standards and several articles dealing with medical exposures: justification, optimisation, recording patient doses, the use of diagnostic reference levels, training, accidental and unintended exposures, etc. have also been included in agreement with the ICRP recommendations.

Standardization of administered activities in pediatric nuclear medicine: a report of the first nuclear medicine global initiative project, part 1-statement of the issue and a review of available resources

The Nuclear Medicine Global Initiative (NMGI) was formed in 2012 and consists of 13 international organizations with direct involvement in nuclear medicine. The underlying objectives of the NMGI were to promote human health by advancing the field of nuclear medicine and molecular imaging, encourage global collaboration in education, and harmonize procedure guidelines and other policies that ultimately lead to improvements in quality and safety in the field throughout the world. For its first project, the NMGI decided to consider the issues involved in the standardization of administered activities in pediatric nuclear medicine. This article presents part 1 of the final report of this initial project of the NMGI. It provides a review of the value of pediatric nuclear medicine, the current understanding of the carcinogenic risk of radiation as it pertains to the administration of radiopharmaceuticals in children, and the application of dosimetric models in children. A listing of pertinent educational and reference resources available in print and online is also provided. The forthcoming part 2 report will discuss current standards for administered activities in children and adolescents that have been developed by various organizations and an evaluation of the current practice of pediatric nuclear medicine specifically with regard to administered activities as determined by an international survey of nuclear medicine clinics and centers. Lastly, the part 2 report will recommend a path forward toward global standardization of the administration of radiopharmaceuticals in children.

Modelling the effects of ionizing radiation on survival of animal population: acute versus chronic exposure

The objective of the present paper was application of a model, which was originally developed to simulate chronic ionizing radiation effects in a generic isolated population, to the case of acute exposure, and comparison of the dynamic features of radiation effects on the population survival in cases of acute and chronic exposure. Two modes of exposure were considered: acute exposure (2-35 Gy) and chronic lifetime exposure with the same integrated dose. Calculations were made for a generic mice population; however, the model can be applied for other animals with proper selection of parameter values. In case of acute exposure, in the range 2-11 Gy, the population response was in two phases. During a first phase, there was a depletion in population survival; the second phase was a recovery period due to reparation of damage and biosynthesis of new biomass. Model predictions indicate that a generic mice population, living in ideal conditions, has the potential for recovery (within a mouse lifetime period) from acute exposure with dose up to 10-11 Gy, i.e., the population may recover from doses above an LD50 (6.2 Gy). Following acute doses above 14 Gy, however, the mice population went to extinction without recovery. In contrast, under chronic lifetime exposures (500 days), radiation had little effect on population survival up to integrated doses of 14-15 Gy, so the survival of a population subjected to chronic exposure was much better compared with that after an acute exposure with the same dose. Due to the effect of "wasted radiation", the integrated dose of chronic exposure could be about two times higher than acute dose, producing the same effect on survival. It is concluded that the developed generic population model including the repair of radiation damage can be applied both to acute and chronic modes of exposure; results of calculations for generic mice population are in qualitative agreement with published data on radiation effects in mice.

Transfer parameters for ICRP reference animals and plants collected from a forest ecosystem

The International Commission on Radiological Protection (ICRP) have suggested the identification of a series of terrestrial, marine and freshwater sites from which samples of each Reference animal and plant (RAP) could be systematically collected and analysed. We describe the first such study in which six of the eight terrestrial RAPs, and associated soil samples, were collected from a site located in a managed coniferous forestry plantation in north-west England. Adult life stages of species representing six of the terrestrial RAPs (Wild grass, Pine tree, Deer, Rat, Earthworm and Bee) were sampled and analysed to determine concentrations of 60 elements and gamma-emitting radionuclides. The resultant data have been used to derive concentration ratios (CR(wo-soil)) relating element/radionuclide concentrations in the RAPs to those in soil. This paper presents the first-reported transfer parameters for a number of the RAP-element combinations. Where possible, the derived CR(wo-soil) values are compared with the ICRPs-recommended values and any appreciable differences discussed.

Establishing a database of radionuclide transfer parameters for freshwater wildlife

Environmental assessments to evaluate potentials risks to humans and wildlife often involve modelling to predict contaminant exposure through key pathways. Such models require input of parameter values, including concentration ratios, to estimate contaminant concentrations in biota based on measurements or estimates of concentrations in environmental media, such as water. Due to the diversity of species and the range in physicochemical conditions in natural ecosystems, concentration ratios can vary by orders of magnitude, even within similar species. Therefore, to improve model input parameter values for application in aquatic systems, freshwater concentration ratios were collated or calculated from national grey literature, Russian language publications, and refereed papers. Collated data were then input into an international database that is being established by the International Atomic Energy Agency. The freshwater database enables entry of information for all radionuclides listed in ICRP (1983), in addition to the corresponding stable elements, and comprises a total of more than 16,500 concentration ratio (CRwo-water) values. Although data were available for all broad wildlife groups (with the exception of birds), data were sparse for many organism types. For example, zooplankton, crustaceans, insects and insect larvae, amphibians, and mammals, for which there were CRwo-water values for less than eight elements. Coverage was most comprehensive for fish, vascular plants, and molluscs. To our knowledge, the freshwater database that has now been established represents the most comprehensive set of CRwo-water values for freshwater species currently available for use in radiological environmental assessments.

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.