ALLIANCE perspectives on integration of humans and the environment into the system of radiological protection.

Risks posed by the presence of radionuclides in the environment require an efficient, balanced, and adaptable assessment for protecting exposed humans and wildlife, and managing the associated radiological risk. Exposure of humans and wildlife originate from the same sources releasing radionuclides to the environment. Environmental concentrations of radionuclides serve as inputs to estimate the dose to man, fauna, and flora, with transfer processes being, in essence, similar, which calls for a common use of transport models. Dose estimates are compared with the radiological protection criteria for humans and wildlife, such as those developed by the International Commission on Radiological Protection. This indicates a similarity in the approaches for impact assessment in humans and wildlife, although some elements are different (e.g. the protection endpoint for humans is stochastic effects on individuals, whereas for wildlife, it is deterministic effects on species and ecosystems). Human and environmental assessments are consistent and complementary in terms of how they are conducted and in terms of the underlying databases (where appropriate). Not having an integrated approach may cause difficulties for operators and regulators, for communication to stakeholders, and may even hamper decision making. For optimised risk assessment and management, the impact from non-radiation contaminants and stressors should also be considered. Both in terms of the underlying philosophy and the application via appropriate tools, the European Radioecology Alliance (ALLIANCE) upholds that integration of human and ecological impact and risk assessment is recommended from several perspectives (e.g. chemical/radiological risks).

COMET strongly supported the development and implementation of medium-term topical research roadmaps consistent with the ALLIANCE Strategic Research Agenda.

The ALLIANCE6 Strategic Research Agenda (SRA) initiated by the STAR7 Network of Excellence and integrated in the research strategy implemented by the COMET consortium, defines a long-term vision of the needs for, and implementation of, research in radioecology. This reference document, reflecting views from many stakeholders groups and researchers, serves as an input to those responsible for defining EU research call topics through the ALLIANCE SRA statement delivered each year to the EJP-CONCERT8 (2015-2020). This statement highlights a focused number of priorities for funding. Research in radioecology and related sciences is justified by various drivers, such as policy changes, scientific advances and knowledge gaps, radiological risk perception by the public, and a growing awareness of interconnections between human and ecosystem health. The SRA is being complemented by topical roadmaps that have been initiated by the COMET9 EC-funded project, with the help and endorsement of the ALLIANCE. The strategy underlying roadmap development is driven by the need for improved mechanistic understanding across radioecology. By meeting this need, we can provide fit-for-purpose human and environmental impact/risk assessments in support of the protection of man and the environment in interaction with society and for the three exposure situations defined by the ICRP (i.e., planned, existing and emergency). Within the framework of the EJP-CONCERT the development of a joint roadmap is under discussion among all the European research platforms and will highlight the major research needs for the whole radiation protection field and how these are likely to be addressed by 2030.

Sustainability and integration of radioecology-position paper.

This position paper gives an overview of how the COMET project (COordination and iMplementation of a pan-European instrumenT for radioecology, a combined Collaborative Project and Coordination and Support Action under the EC/Euratom 7th Framework Programme) contributed to the integration and sustainability of radioecology in Europe via its support to and interaction with the European Radioecology ALLIANCE. COMET built upon the foundations laid by the FP7 project STAR (Strategic Network for Integrating Radioecology) Network of Excellence in radioecology. In close association with the ALLIANCE, and based on the Strategic Research Agenda (SRA), COMET developed innovative mechanisms for joint programming and implementation of radioecological research. To facilitate and foster future integration under a common federating structure, research activities developed within COMET were targeted at radioecological research needs identified in the SRA. Furthermore, COMET maintained and developed strong mechanisms for knowledge exchange, dissemination and training to enhance and maintain European capacity, competence and skills in radioecology. In the short term the work to promote radioecology will continue under the H2020 project EJP-CONCERT (European Joint Programme for the Integration of Radiation Protection Research). The EJP-CONCERT project (2015-2020) aims to develop a sustainable structure for promoting and administering joint programming and open research calls in the field of radiation protection research for Europe. In the longer term, radioecological research will be facilitated by the ALLIANCE. External funding is, however, required in order to be able to answer emerging research needs.

Combined effects of depleted uranium and ionising radiation on zebrafish embryos.

In the environment, living organisms are exposed to a mixture of stressors, and the combined effects are deemed as multiple stressor effects. In the present work, the authors studied the multiple stressor effect in embryos of the zebrafish (Danio rerio) from simultaneous exposure to alpha particles and depleted uranium (DU) through quantification of apoptotic signals at 24 h post-fertilisation (hpf) revealed by vital dye acridine orange staining. In each set of experiments, dechorionated zebrafish embryos were divided into 4 groups, each having 10 embryos: Group (C) in which the embryos did not receive any further treatment; Group (IU) in which the embryos received an alpha-particle dose of 0.44 mGy at 5 hpf and were then exposed to 100 µg l(-1) of DU from 5 to 6 hpf; Group (I) in which the embryos received an alpha-particle dose of 0.44 mGy at 5 hpf and Group (U) in which the dechorionated embryos were exposed to 100 µg l(-1) of DU from 5 to 6 hpf. The authors confirmed that an alpha-particle dose of 0.44 mGy and a DU exposure for 1 h separately led to hormetic and toxic effects assessed by counting apoptotic signals, respectively, in the zebrafish. Interestingly, the combined exposure led to an effect more toxic than that caused by the DU exposure alone, so effectively DU changed the beneficial effect (hormesis) brought about by alpha-particle irradiation into an apparently toxic effect. This could be explained in terms of the promotion of early death of cells predisposed to spontaneous transformation by the small alpha-particle dose (i.e. hormetic effect) and the postponement of cell death upon DU exposure.

Establishing relationships between environmental exposures to radionuclides and the consequences for wildlife: inferences and weight of evidence.

Ecological risk assessments for radioactive substances are based on a number of inference rules to compensate for knowledge gaps, and generally require the implementation of a weight-of-evidence approach. Until recently, dose (rate)-response relationships used to derive radioprotection criteria for wildlife have mainly relied on laboratory studies from a limited number of species as representatives of biodiversity. There is no doubt that additional knowledge, combined with advanced conceptual and mathematical approaches, is needed to develop general rules and increase confidence when extrapolating from test species to complex biological/ecological systems. Moreover, field data sets based on robust sampling strategies are still needed to validate benchmark values derived from controlled laboratory tests, and to indicate potential indirect ecological effects, if any. This paper illustrates, through several examples, the need for implementing a combined laboratory-field-model approach to obtain science-based benchmark doses (or dose rates) (e.g. screening benchmarks for ecological risk assessments or derived consideration reference levels), based on robust meta-analysis of dose-effect relationships covering ecologically relevant exposure time scales, species, and endpoints.

Soil nematode assemblages as bioindicators of radiation impact in the Chernobyl Exclusion Zone.

In radioecology, the need to understand the long-term ecological effects of radioactive contamination has been emphasised. This requires that the health of field populations is evaluated and linked to an accurate estimate of received radiological dose. The aim of the present study was to assess the effects of current radioactive contamination on nematode assemblages at sites affected by the fallout from the Chernobyl accident. First, we estimated the total dose rates (TDRs) absorbed by nematodes, from measured current soil activity concentrations, Dose Conversion Coefficients (DCCs, calculated using EDEN software) and soil-to-biota concentration ratios (from the ERICA tool database). The impact of current TDRs on nematode assemblages was then evaluated. Nematodes were collected in spring 2011 from 18 forest sites in the Chernobyl Exclusion Zone (CEZ) with external gamma dose rates, measured using radiophotoluminescent dosimeters, varying from 0.2 to 22 µGy h(-1). These values were one order of magnitude below the TDRs. A majority of bacterial-, plant-, and fungal-feeding nematodes and very few of the disturbance sensitive families were identified. No statistically significant association was observed between TDR values and nematode total abundance or the Shannon diversity index (H'). The Nematode Channel Ratio (which defines the relative abundance of bacterial- versus fungal-feeding nematodes) decreased significantly with increasing TDR, suggesting that radioactive contamination may influence nematode assemblages either directly or indirectly by modifying their food resources. A greater Maturity Index (MI), usually characterising better soil quality, was associated with higher pH and TDR values. These results suggest that in the CEZ, nematode assemblages from the forest sites were slightly impacted by chronic exposure at a predicted TDR of 200 µGy h(-1). This may be imputable to a dominant proportion of pollutant resistant nematodes in all sites. This might result from a selection at the expense of sensitive species after the accident.

Are radiosensitivity data derived from natural field conditions consistent with data from controlled exposures? A case study of Chernobyl wildlife chronically exposed to low dose rates.

The discrepancy between laboratory or controlled conditions ecotoxicity tests and field data on wildlife chronically exposed to ionising radiation is presented for the first time. We reviewed the available chronic radiotoxicity data acquired in contaminated fields and used a statistical methodology to support the comparison with knowledge on inter-species variation of sensitivity to controlled external γ irradiation. We focus on the Chernobyl Exclusion Zone and effects data on terrestrial wildlife reported in the literature corresponding to chronic dose rate exposure situations (from background ~100 nGy/h up to ~10 mGy/h). When needed, we reconstructed the dose rate to organisms and obtained consistent unbiased data sets necessary to establish the dose rate-effect relationship for a number of different species and endpoints. Then, we compared the range of variation of radiosensitivity of species from the Chernobyl-Exclusion Zone with the statistical distribution established for terrestrial species chronically exposed to purely gamma external irradiation (or chronic Species radioSensitivity Distribution - SSD). We found that the best estimate of the median value (HDR50) of the distribution established for field conditions at Chernobyl (about 100 µGy/h) was eight times lower than the one from controlled experiments (about 850 µGy/h), suggesting that organisms in their natural environmental were more sensitive to radiation. This first comparison highlights the lack of mechanistic understanding and the potential confusion coming from sampling strategies in the field. To confirm the apparent higher sensitive of wildlife in the Chernobyl Exclusion Zone, we call for more a robust strategy in field, with adequate design to deal with confounding factors.

An invitation to contribute to a strategic research agenda in radioecology.

With intentions of integrating a portion of their respective research efforts into a trans-national programme that will enhance radioecology, eight European organisations recently formed the European Radioecology ALLIANCE (www.er-alliance.org). The ALLIANCE is an Association open to other organisations throughout the world with similar interests in promoting radioecology. The ALLIANCE members recognised that their shared radioecological research could be enhanced by efficiently pooling resources among its partner organizations and prioritising group efforts along common themes of mutual interest. A major step in this prioritisation process was to develop a Strategic Research Agenda (SRA). An EC-funded Network of Excellence in Radioecology, called STAR (Strategy for Allied Radioecology), was formed, in part, to develop the SRA. This document is the first published draft of the SRA. The SRA outlines a suggested prioritisation of research topics in radioecology, with the goal of improving research efficiency and more rapidly advancing the science. It responds to the question: "What topics, if critically addressed over the next 20 years, would significantly advance radioecology?" The three Scientific Challenges presented within the SRA, with their 15 associated research lines, are a strategic vision of what radioecology can achieve in the future. Meeting these challenges will require a directed effort and collaboration with many organisations the world over. Addressing these challenges is important to the advancement of radioecology and in providing scientific knowledge to decision makers. Although the development of the draft SRA has largely been a European effort, the hope is that it will initiate an open dialogue within the international radioecology community and its stakeholders. This is an abbreviated document with the intention of introducing the SRA and inviting contributions from interested stakeholders. Critique and input for improving the SRA are welcomed via a link on the STAR website (www.star-radioecology.org).

Effects of chronic exposure in populations of Koeleria gracilis Pers. from the Semipalatinsk nuclear test site, Kazakhstan.

Morphological and cytogenetic abnormalities were examined in crested hairgrass (Koeleria gracilis Pers.) populations inhabiting the Semipalatinsk nuclear test site (STS), Kazakhstan. Sampling of biological material and soil was carried out during 3 years (2005-2007) at 4 sites within the STS. Activity concentrations of 10 radionuclides and 8 heavy metals content in soils were measured. Doses absorbed by plants were estimated and varied, depending on the plot, from 4 up to 265 mGy/y. The frequency of cytogenetic alterations in apical meristem of germinated seeds from the highly contaminated plot significantly exceeded the level observed at other plots with lower levels of radioactive contamination during all three years of the study. A significant excess of chromosome aberrations, typical for radiation exposure, as well as a dependence of the frequency of these types of mutations on dose absorbed by plants were revealed. The results indicate the role radioactive contamination plays in the occurrence of cytogenetic effects. However, no radiation-dependent morphological alterations were detected in the progeny of the exposed populations. Given that the crested hairgrass populations have occupied the radioactively contaminated plots for some 50 years, adaptation to the radiation stress was not evident. The findings obtained were in agreement with the benchmark values proposed in the FASSET and ERICA projects to restrict radiation impacts on biota.

A multi-criteria weight of evidence approach for deriving ecological benchmarks for radioactive substances.

Dose rate benchmarks are required in the tiered approaches used to screen out benign exposure scenarios in radiological ecological risk assessment. Such screening benchmarks, namely the predicted no-effect dose rates (PNEDR), have been derived by applying, as far as possible, the European guidance developed for chemicals. To derive the ecosystem level (or generic) PNEDR, radiotoxicity EDR(10) data (dose rates giving a 10% effect in comparison with the control) were used to fit a species sensitivity distribution (SSD) and estimate the HDR(5) (the hazardous dose rate affecting 5% of species with a 10% effect). Then, a multi-criteria approach was developed to justify using an assessment factor (AF) to apply to the HDR(5) for estimating a PNEDR value. Several different statistical data treatments were considered which all gave reasonably similar results. The suggested generic screening value of 10 microGy h(-1) (incremental dose rate) was derived using the lowest available EDR(10) value per species, an unweighted SSD, and an AF of 2 applied to the estimated HDR(5). Consideration was also given to deriving screening benchmark values for organism groups but this was not thought to be currently appropriate due to few relevant data being currently available.

Protection of the environment from ionising radiation in a regulatory context--an overview of the PROTECT coordinated action project.

The outcome of the PROTECT project (Protection of the Environment from Ionising Radiation in a Regulatory Context) is summarised, focusing on the protection goal and derivation of dose rates which may detrimentally affect wildlife populations. To carry out an impact assessment for radioactive substances, the estimated dose rates produced by assessment tools need to be compared with some form of criteria to judge the level of risk. To do this, appropriate protection goals need to be defined and associated predefined dose rate values, or benchmarks, derived and agreed upon. Previous approaches used to estimate dose rates at which there may be observable changes in populations or individuals are described and discussed, as are more recent derivations of screening benchmarks for use in regulatory frameworks. We have adopted guidance and procedures used for assessment and regulation of other chemical stressors to derive benchmarks. On the basis of consultation with many relevant experts, PROTECT has derived a benchmark screening dose rate, using data on largely reproductive effects to derive species sensitivity distributions, of 10 microGy h(-1) which can be used to identify situations which are below regulatory concern with a high degree of confidence.

Issues and practices in the use of effects data from FREDERICA in the ERICA Integrated Approach.

The ERICA Integrated Approach requires that a risk assessment screening dose rate is defined for the risk characterisation within Tiers 1 and 2. At Tier 3, no numerical screening dose rate is used, and the risk characterisation is driven by methods that can evaluate the possible effects of ionising radiation on reproduction, mortality and morbidity. Species sensitivity distribution has been used to derive the ERICA risk assessment predicted no-effect dose rate (PNEDR). The method used was based on the mathematical processing of data from FRED (FASSET radiation effects database merged with the EPIC database to form FREDERICA) and resulted in a PNEDR of 10 microGy/h. This rate was assumed to ascribe sufficient protection of all ecosystems from detrimental effects on structure and function under chronic exposure. The value was weighed against a number of points of comparison: (i) PNEDR values obtained by application of the safety factor method, (ii) background levels, (iii) dose rates triggering effects on radioactively contaminated sites and (iv) former guidelines from literature reviews. In Tier 3, the effects analysis must be driven by the problem formulation and is thus highly case specific. Instead of specific recommendations on numeric values, guidance on the sorts of methods that may be applied for refined effect analysis is provided and illustrated.

Modelling the propagation of effects of chronic exposure to ionising radiation from individuals to populations.

This study evaluated the potential effect of ionising radiation on population growth using simple population models and parameter values derived from chronic exposure experiments in two invertebrate species with contrasting life-history strategies. In the earthworm Eisenia fetida, models predicted increasing delay in population growth with increasing gamma dose rate (up to 0.6 generation times at 11 mGy h(-1)). Population extinction was predicted at 43 mGy h(-1). In the microcrustacean Daphnia magna, models predicted increasing delay in population growth with increasing alpha dose rate (up to 0.8 generation times at 15.0 mGy h(-1)), only after two successive generations were exposed. The study examined population effects of changes in different individual endpoints (including survival, number of offspring produced and time to first reproduction). Models showed that the two species did not respond equally to equivalent levels of change, the fast growing daphnids being more susceptible to reduction in fecundity or delay in reproduction than the slow growing earthworms. This suggested that susceptibility of a population to ionising radiation cannot be considered independent of the species' life history.

Increased effects of internal alpha irradiation in Daphnia magna after chronic exposure over three successive generations.

A 70-day experiment was performed with Daphnia magna exposed to waterborne Am-241 on a range of concentrations (from 0.4 to 40 Bq ml(-1)) in order to test chronic effects of internal alpha irradiation on respiration, somatic growth and reproduction over three successive generations. Changes in Am-241 concentrations were followed in the water and in daphnid tissues, eggs and cuticles. Corresponding average dose rates of 0.3, 1.5 and 15 mGy h(-1) were estimated. This study confirmed that oxygen consumption increased significantly in the first generation (F0) after 6 days of exposure to a dose rate >or=1.5 mGy h(-1). Consequences were limited to a reduction in body length (5%) and dry mass of females (16%) and eggs (8%) after 23 days of exposure, while mortality and fecundity remained unaffected. New cohorts were started with neonates of broods 1 and 5, to examine potential consequences of the reduced mass of offspring for subsequent exposed generations. Results strongly contrasted with those observed in F0. At the highest dose rate, an early mortality of 38-90% affected juveniles while survivors showed delayed reproduction and reduced fecundity in F1 and F2. At 0.3 and 1.5 mGy h(-1), mortality ranged from 31 to 38% of daphnids depending on dose rate, but was observed only in generation F1 started with neonates of the brood 1. Reproduction was affected through a reduction in the proportion of breeding females, occurring in the first offspring generation at 1.5 mGy h(-1) (to 62% of total daphnids) and in the second generation at 0.3 mGy h(-1) (to 69% of total daphnids). Oxygen consumption remained significantly higher at dose rates >or=0.3 mGy h(-1) than in the control in almost every generation. Body size and mass continued decreasing in relation to dose rate, with a significant reduction in mass ranging from 15% at 0.3 mGy h(-1) to 27% at 15 mGy h(-1) in the second offspring generation.

Effects of chronic internal alpha irradiation on physiology, growth and reproductive success of Daphnia magna.

Daphnids were chronically exposed to waterborne Am-241, an alpha-emitting radionuclide, ranging in concentration from 0.4 to 40 Bq ml(-1). Am-241 amounts were monitored in the medium, daphnid tissues and cuticles. Corresponding average dose rates of 0.02, 0.11 and 0.99 mGy h(-1) were calculated for whole organisms with internal alpha-radiation contributing 99% of total dose rates. Effects of internal alpha irradiation on respiration and ingestion rates, adult, egg and neonate individual dry masses, fecundity and larval resistance to starvation were examined in 23-day experiments. Daphnids showed increased respiratory demand after 23 days at the highest dose rate, suggesting increased metabolic cost of maintenance due to coping with alpha radiological stress. Although no effect was detected on ingestion rates between contaminated and control daphnids, exposure to dose rates of 0.11 mGy h(-1) or higher, resulted in a significant 15% reduction in body mass. Fecundity remained unchanged over the 23-day period, but individual masses of eggs and neonates were significantly smaller compared to the control. This suggested that increased metabolic expenditure in chronically alpha-radiated daphnids came at the expense of their energy investment per offspring. As a consequence, neonates showed significantly reduced resistance to starvation at every dose rate compared to the control. Our observations are discussed in comparison with literature results reported for cadmium, a chemical toxicant which affects feeding activity and strongly reduces individual energy uptake.

Modeling radiological dose in non-human species: principles, computerization, and application.

Due to the increasing interest in environmental protection against ionizing radiation on the international scene, the need for operational tools for radiological environmental risk assessment is becoming critical. Within this framework, this paper puts forward a fast and user-friendly computerized method to allow the transformation from exposure (expressed in Bq per unit of mass or volume) to dose (i.e., the energy deposited in the organism, expressed in Gy) received from any radionuclide by any non-human species, for a unit of time and a unit of "concentration" of radionuclide in the radiation source. The calculation principles used to determine this dose coefficient, expressed in Gy/unit of time per Bq/unit of volume or mass, are described for gamma, beta, and alpha radiation. Both internal and external exposure situations are considered. The domain of validity of the proposed model is specified, as is the way in which it has been computerized. The paper concludes by verifying the numerical accuracy of the tool and making initial comparisons between results from the described method and those developed at the European level.

Biomarker responses in juvenile rainbow trout (Oncorhynchus mykiss) after single and combined exposure to low doses of cadmium, zinc, PCB77 and 17beta-oestradiol.

The objective of this study was to examine (i) the biochemical responses of rainbow trout exposed to sublethal water concentrations of the metals cadmium (Cd) (1.5 microg l(-1)) and zinc (Zn) (150 microg l(-1)); and (ii) the potential combined effects when applied in mixture (Cd/Zn) with and without co-exposure to model organic chemicals 3,3',4,4'-tetrachlorobiphenyl (PCB77) (1 mg kg (-1)) and 17beta-oestradiol (E2) (0.5 mg kg(-1)). After 21 days of exposure, several biomarkers were assessed in the liver (enzymatic and nonenzymatic antioxidants, heat shock proteins [HSP70 and HSP60], ethoxyresorufin-O-deethylase [EROD]) and in the plasma (vitellogenin [Vtg], aminotransferases). Plasma aminotransferases were not affected, whereas the other biomarkers showed different patterns of response depending on the treatment. For example, Cd, and Zn to a lesser extent, induced an adaptive response in the liver shown by an increase in antioxidant defences (total glutathione [GSH], superoxide dismutase, Trolox equivalent antioxidant capacity [TEAC]), without any impairment of GSH redox status or induction of heat shock proteins. Antagonistic effects were observed in GSH-related biomarkers after Cd/Zn exposure. PCB77 strongly induced EROD activity, HSP70 and TEAC. Co-exposure with metals did not modulate significantly the effects of PCB77. E2 induced Vtg and inhibited liver antioxidants and basal EROD activity. These inhibitory effects were suppressed in fishes exposed to E2 + Cd/Zn, suggesting additive effects of E2 and metals. In addition, E2-induced Vtg was not altered by metals. Multivariate analyses confirmed some correlation between the biomarkers. The use of complementary biomarkers is necessary to discriminate different treatments and to highlight interactive effects.

CASTEAUR: a simple tool to assess the transfer of radionuclides in waterways.

The CASTEAUR project proposes a simplified tool to assess the transfer of radionuclides between and in the main biotic and abiotic components of the freshwater ecosystem. Applied to phenomenological modeling, various hypotheses simplify the transfer equations, which, when programmed under Excel, can be readily dispatched and used. CASTEAUR can be used as an assessment tool for impact studies of accidental release as well as "routine" release. This code is currently being tested on the Rhone River, downstream from a nuclear reprocessing plant. The first results are reported to illustrate the possibilities offered by CASTEAUR.