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Since the accident at the Chornobyl Nuclear Power Plant in 1986, there have been few studies published on medium and large mammals inhabiting the area from which the human population was removed (now referred to as the Chornobyl Exclusion Zone, CEZ). The dataset presented in this paper describes a motion-activated camera trap study (n=21 cameras) conducted from September 2016 to September 2017 in the Red Forest located within the Chornobyl Exclusion Zone. The Red Forest, which is likely the most anthropogenically contaminated radioactive terrestrial ecosystem on earth, suffered a severe wildfire in July 2016. The motion-activated trap cameras were therefore in place as the Red Forest recovered from the wildfire. A total of 45 859 images were captured, and of these 19 391 contained identifiable species or organism types (e.g. insects). A total of 14 mammal species were positively identified together with 23 species of birds (though birds were not a focus of the study). Weighted absorbed radiation dose rates were estimated for mammals across the different camera trap locations; the number of species observed did not vary with estimated dose rate. We also observed no relationship between estimated weighted absorbed radiation dose rates and the number of triggering events for the four main species observed during the study (brown hare, Eurasian elk, red deer, roe deer). The data presented will be of value to those studying wildlife within the CEZ from the perspectives of the potential effects of radiation on wildlife and also rewilding in this large, abandoned area. They may also have value in any future studies investigating the impacts of the recent Russian military action in the CEZ. The data and supporting documentation are freely available from the Environmental Information Data Centre (EIDC) under the terms and conditions of a Creative Commons Attribution (CC BY) license: https://doi.org/10.5285/bf82cec2-5f8a-407c-bf74-f8689ca35e83 (Barnett et al., 2022a).

Since the accident at the Chornobyl nuclear power plant in 1986 there have been few studies published on medium/large mammals inhabiting the area from which the human population was removed (now referred to as the Chornobyl Exclusion Zone). The dataset presented in this paper describes a motion activated camera trap study (n=21 cameras) conducted from September 2016–September 2017 in the Red Forest located within the Chornobyl Exclusion Zone. The Red Forest, which is likely the most anthropogenically contaminated radioactive terrestrial ecosystem on earth, suffered a severe wildfire in July 2016. The motion activated trap cameras were therefore in place as the Red Forest recovered from the wildfire. A total of 45859 images were captured and of these 19391 contained identifiable species or organism types (e.g. insects). A total of 14 mammal species were positively identified together with 23 species of birds (though birds were not a focus of the study). Weighted absorbed radiation dose rate rates were estimated for mammals across the different camera trap locations; the number of species observed did not vary with estimated dose rate. We also observed no relationship between estimated weighted absorbed radiation dose rates and the number of triggering events for the four main species observed during the study (Brown hare, Eurasian elk, Red deer, Roe deer). The data presented will be of value to those studying wildlife within the CEZ both from the perspectives of the potential effects of radiation on wildlife and also rewilding in this large, abandoned area. They may also have value in any future studies investigating the impacts of the recent Russian military action in the CEZ. The data and supporting documentation are freely available from the Environmental Information Data Centre (EIDC) under the terms and conditions of a Creative Commons Attribution (CC BY) licence: https://doi.org/10.5285/bf82cec2-5f8a-407c-bf74-f8689ca35e83 (Barnett et al. 2022a).

Following the 1986 Chornobyl accident an area of approaching 5000 km2 surrounding the nuclear plant was abandoned, creating the Chornobyl Exclusion Zone (CEZ). Whilst this area likely contains the most radioactive terrestrial ecosystem on earth, over the nearly 35 years since the accident the absence of humans and associated activities has resulted in increases in wildlife numbers. Both the Belarussian and Ukrainian components of the CEZ are now designated as nature reserves; together they form one of Europe's largest protected areas and have been described as an iconic example of rewilding. Forests and former agricultural land (now scrub) dominate the CEZ and wildfires are an annual event. In April 2020, the CEZ suffered its most widespread fires to date when >800 km2 of the 2600 km2 Ukrainian portion of the CEZ was burnt. Largescale fires in the CEZ have implications for wildlife, as they do elsewhere, but they also pose additional radioecological and radiological protection questions. We discuss the implications of wildfires in the CEZ, considering effects on wildlife and changes in radionuclide mobility. We also demonstrate that the risk to firefighters and the wider public from the inhalation of radionuclides in smoke resulting from fires in the CEZ is likely to be low. However, further experimental and modelling work to evaluate potential doses to firefighters from inhaled radioactive particles would be valuable, not least for reassurance purposes.

Environmental impacts of the 1986 Chernobyl Nuclear Power Plant accident are much debated, but the effects of radiation on host microbiomes have received little attention to date.\ud \ud We present the first analysis of small mammal gut microbiome from the Chernobyl Exclusion Zone in relation to total absorbed dose rate and including caecum as well as faeces sample.\ud \ud We provide novel evidence that host species determines fungal community composition, and that associations between microbiome (both bacterial and fungal) communities and radiation exposure varies between host species. Using ambient versus total weighted absorbed dose rates in analyses produced different results, with the latter more robust for interpreting microbiome changes at the individual level. We found considerable variation between results for faecal and gut samples of bank voles, suggesting faecal samples are not an accurate indicator of gut composition.\ud \ud Associations between radiation exposure and microbiome composition of gut samples were not robust against geographical variation, although we identified families of bacteria (Lachnospiraceae and Muribaculaceae) and fungi (Steccherinaceae and Strophariaceae) in the guts of bank voles that may serve as biomarkers of radiation exposure.\ud \ud Further studies considering a range of small mammal species are needed to establish the robustness of these potential biomarkers.

There are international recommendations that the environment (i.e. wildlife) is assessed for the potential impact of releases of ionising radiation. The transfer of radionuclides to wildlife from media (e.g. soil, water) is usually described using the whole-organism concentration ratio (CRwo-media) and a number of assessment models use these values to estimate radiation exposure and risk to wildlife; however, there are many gaps in knowledge. This paper describes a study conducted in 2015–2016 to sample terrestrial wildlife, soil and water from two forests in north-east England. Sampling was targeted towards species representative of the International Commission on Radiological Protection's (ICRP) terrestrial Reference Animals and Plants (RAPs): Wild Grass (Poaceae family), Pine Tree (Pinaceae family), Earthworm (Lumbricidae family), Bee (Apidae family), Rat (Muridae family), Deer (Cervidae family) and Frog (Ranidae family); opportunistic sampling of plant and fungi species was also conducted. The dataset comprises stable element concentrations for 30 elements, radionuclide activity concentrations for K-40 and Cs-137, and radionuclide and stable element concentration ratios (CRwo-media). These data have significantly increased the number of CRwo-media values available for the ICRP RAPs and will contribute to the development of the ICRP's environmental protection framework. Data will be included in the international database of wildlife transfer parameters for radioecological models and hence are likely to contribute to model developments in the future. All data and supporting documentation are freely available from the Environmental Information Data Centre (EIDC; https://eidc.ac.uk/) under the terms and conditions of the Open Government Licence (Barnett et al., 2020 https://doi.org/10.5285/8f85c188-a915-46ac-966a-95fcb1491be6).

The modelling of transfer of radionuclides from soils to plants generally relies upon empirical soil-plant concentration ratios. Concentration ratios are often highly uncertain and are not available for many plant-radionuclide combinations. A number of papers published over the last 20 years have suggested that phylogenetic models could be used to make predictions of the radionuclide transfer to plants. Such a modelling approach would have the advantage that site factors (typically related to soils) are taken into account. For the first time we have compared predictions of Cs and Sr transfer to a range of crops grown on different soils. Predictions for both elements were generally acceptable (within an order of magnitude of observed data) but Sr concentrations were over predicted in fruits and tubers. This over prediction of Sr concentrations is likely to be because the phylogenetic models were fitted to data for green shoots. We conclude that phylogenetic models offer a number of advantages, but that they must be validated and, in future, parametrisation datasets need to include data on concentrations in edible plant parts and not just green shoots.

Environmental impacts of the 1986 Chernobyl Nuclear Power Plant accident are much debated, but the effects of radiation on host microbiomes has received little attention to date. We present the first analysis of small mammal gut microbiome from the Chernobyl Exclusion Zone in relation to total absorbed dose rate and including caecum as well as faeces sample. The associations between microbiome communities and radiation exposure varied between host species. Associations between microbiome and radiation was different for analyses based on ambient versus total weighted absorbed dose rates. We found considerable variation between patterns for faecal and gut samples of bank voles, suggesting faecal samples are not an accurate indicator of gut composition. For bank vole guts, associations between radiation and bacterial community composition were robust against geographical and habitat variation. We found limited associations between radiation and fungal communities. Host physiological mechanisms or environmental factors may be driving these patterns.

The objective of this paper is to consider the implications of employing process-based models on predictions for radionuclide activity concentrations in grass and cow milk. The FDMT (Food Chain and Dose Module for Terrestrial Pathways as used in the JRODOS and ARGOS decision support systems) model has been transferred to a modelling platform enabling sub-models to be modified and replaced. Primarily, this has involved invoking process-based models for 137Cs and 90Sr that account for soil chemistry in simulating bioavailability and plant transfer. The implementation of such models can lead to quite dramatic differences in predicted activity concentrations of radionuclides in grass and milk compared to a default FDMT set-up for time periods later than a few weeks post deposition. Considering transfer within a spatial context, by combining information from the outputs of process-based models with illustrative soil maps, leads to the observation that the most elevated 137Cs and 90Sr concentrations in grass and milk might not necessarily occur in areas where deposition is highest. Not accounting for soil type when modelling food chain transfer might lead to the sub-optimal allocation of resources or misidentification of the most vulnerable areas in the long-term after an accidental release.

This study addresses a significant data deficiency in the developing environmental protection framework of the International Commission on Radiological Protection, namely a lack of radionuclide transfer data for some of the Reference Animals and Plants (RAPs). It is also the first study that has sampled such a wide range of species (invertebrates, plants, amphibians and small mammals) from a single terrestrial site in the Chernobyl Exclusion Zone (CEZ). Samples were collected in 2014 from the 0.4 km2 sampling site, located 5 km west of the Chernobyl Nuclear Power complex. We report radionuclide (137Cs, 90Sr, 241Am and Pu-isotopes) and stable element concentrations in wildlife and soil samples and use these to determine whole organism-soil concentration ratios and absorbed dose rates.Increasingly, stable element analyses are used to provide transfer parameters for radiological models. The study described here found that for both Cs and Sr the transfer of the stable element tended to be lower than that of the radionuclide; this is the first time that this has been demonstrated for Sr, though it is in agreement with limited evidence previously reported for Cs.Studies reporting radiation effects on wildlife in the CEZ generally relate observations to ambient dose rates determined using handheld dose meters. For the first time, we demonstrate that ambient dose rates may underestimate the actual dose rate for some organisms by more than an order of magnitude. When reporting effects studies from the CEZ, it has previously been suggested that the area has comparatively low natural background dose rates. However, on the basis of data reported here, dose rates to wildlife from natural background radionuclides within the CEZ are similar to those in many areas of Europe. © 2018 The Authors., The work described in this paper was largely supported by the TREE project ( www.ceh.ac.uk/TREE ) which is funded by the Natural Environment Research Council ( NE/L000318/1 , NE/L000520/1 , NE/L000504/1 ), the Environment Agency and Radioactive Waste Management Ltd. under the RATE programme. Additional funding for radioanalyses was provided to Chornobyl Center by the EU funded COMET project ( http://www.comet-radioecology.org/ ). Thanks go to Scott Young (University of Nottingham), Claire Wells (NERC-CEH) and Jacky Chaplow (NERC-CEH) for their advice and support during this work. Appendix A

The data set "Post Chernobyl surveys of radiocaesium in soil, vegetation, wildlife and fungi in Great Britain" was developed to enable data collected by the Natural Environment Research Council after the Chernobyl accident to be made publicly available. Data for samples collected between May 1986 (immediately after Chernobyl) to spring 1997 are presented. Additional data to radiocaesium concentrations are presented where available. The data have value in trying to assess the contribution of new sources of radiocaesium in the environment, providing baseline data for future planned releases and to aid the development and testing of models. The data are freely available for non-commercial use under Open Government Licence terms and conditions. doi:10.5285/d0a6a8bf-68f0-4935-8b43-4e597c3bf251. Supporting information to assist with the reuse of this data is available from the Environmental Information Data Centre (EIDC) (http://eidc.ceh.ac.uk/).

The 2014 Strategic Research Agenda (SRA) for Radioecology identified the key challenge in education and training (E&T) as being 'to maintain and develop a skilled workforce in Europe and world-wide, through university candidates and professionals trained within radioecology' since 'scientific research in radioecology and application of that knowledge ... requires scientists and workers with adequate competence and appropriate skills.' Radioecology is a multidisciplinary science and E&T is needed by both students and professionals within research, industry and radiation protection. In order to address these needs, the EU COMET project has developed an E&T web platform and arranged a number of field courses, training courses, PhD and MSc courses, refresher courses and workshops, drawing on the COMET consortium to assemble relevant experts. In addition, COMET has been engaged in discussions with stakeholders for more long-term solutions to maintain the sustainability of radioecology E&T after the end of the project. Despite much progress in some areas, many of the challenges outlined in the 2014 SRA remain, mainly due to the lack of sustainable dedicated funding. Future plans within the ALLIANCE radioecology platform and the CONCERT-European Joint Programme for the Integration of Radiation Protection Research must urgently address this lack of sustainability if radioecological competence is to be maintained in Europe.

Under the International Atomic Energy Agency (IAEA) MODARIA (Modelling and Data for Radiological Impact Assessments) Programme, there has been an initiative to improve the derivation, provenance and transparency of transfer parameter values for radionuclides from feed to animal products that are for human consumption. A description of the revised MODARIA 2016 cow milk dataset is described in this paper. As previously reported for the MODARIA goat milk dataset, quality control has led to the discounting of some references used in IAEA's Technical Report Series (TRS) report 472 (IAEA, 2010). The number of Concentration Ratio (CR) values has been considerably increased by (i) the inclusion of more literature from agricultural studies which particularly enhanced the stable isotope data of both CR and Fm and (ii) by estimating dry matter intake from assumed liveweight. In TRS 472, the data for cow milk were 714 transfer coefficient (Fm) values and 254 CR values describing 31 elements and 26 elements respectively. In the MODARIA 2016 cow milk dataset, Fm and CR values are now reported for 43 elements based upon 825 data values for Fm and 824 for CR. The MODARIA 2016 cow milk dataset Fm values are within an order of magnitude of those reported in TRS 472. Slightly bigger changes are seen in the CR values, but the increase in size of the dataset creates greater confidence in them. Data gaps that still remain are identified for elements with isotopes relevant to radiation protection.

The quality and quantity of data used to derive transfer parameter values for milk are variable and there are many data gaps for elements/radionuclides which may need to be considered for risk assessment of the agricultural foodchain. There has been a recent focus on critically evaluating current methods to fill data gaps and on identifying extrapolation methods to derive suitable values for the elements, and particularly radioisotopes, with no or sparse data. The relationship between fractional absorption of elements in the ruminant gastrointestinal tract and transfer to milk has been explored to determine whether knowledge of the former can be used to predict the latter. A relationship has been derived between fractional absorption of elements and two empirical ratios commonly used to quantify transfer to milk; transfer coefficients (element concentration in milk divided by element daily intake) and concentrations ratios (concentration in milk divided by concentration in feed). We propose that fractional absorption may be used to predict the order of magnitude of the transfer to milk of elements/radionuclides for which no relevant data have yet been identified or collated.

Following the Fukushima accident in March 2011, grass samples were collected from 42 sites around Great Britain during April 2011. Iodine-131 was measurable in grass samples across the country with activity concentrations ranging from 10 to 55 Bq kg(-1) dry matter. Concentrations were similar to those reported in other European countries. Rainwater and some foodstuffs were also analysed from a limited number of sites. Of these, (131)I was only detectable in sheep's milk (c. 2 Bq kg(-1)). Caesium-134, which can be attributed to releases from the Fukushima reactors, was detectable in six of the grass samples (4-8 Bq kg(-1) dry matter); (137)Cs was detected in a larger number of grass samples although previous release sources (atmospheric weapons test and the 1986 Chernobyl and 1957 Windscale accidents) are likely to have contributed to this.

The IAEA has recently collated data for a handbook on transfer of radionuclides to wildlife (pending publication as a Technical Reports Series (TRS) document, see Howard et al. (2011)). During this process key data deficiencies were identified, one of which is the lack of data for many elements for birds. The majority of the available transfer data for birds are for game species (e.g. Lagopus spp.) and small song birds. The aim of this study was to consider the feasibility of using a predatory bird sample archive to derive whole organism concentration ratio (CRwo-soil) values for owls for a range of elements relevant to radiological assessments. The CRwo-soil is defined here as the ratio between the concentration of an element/radionuclide in owls (whole organism), measured in Bq kg-1 or mg kg-1 fresh weight (fw) and the concentration of the same element/radionuclide in soil, measured in Bq kg-1 or mg kg-1 dry weight (dw). The Barn (Tyto alba) and Tawny (Strix aluco) owls were selected as examples of a widespread, terrestrial, predatory bird for which archived samples from 2008 were available from the Predatory Bird Monitoring Scheme (PBMS). Their predominant habitats are rough grassland, field and watercourse ‘edges’, and grass strips alongside woods. They have an average home range of approximately 3 km2 and their diet is predominantly rodents (especially voles) and small birds (Taylor, 1994). The PBMS scheme (http://pbms.ceh.ac.uk/) is a long-term (1970 onwards), large scale project which holds a sample archive of 32000 tissues and eggs of predatory birds from throughout the UK. Its aim is to quantify accumulation of contaminants and their effects in predatory birds. The birds submitted to the project have been found dead, usually from road accidents.

A number of models are being used to assess the potential environmental impact of releases of radioactivity. These often use a tiered assessment structure whose first tier is designed to be highly conservative and simple to use. An aim of using this initial tier is to identify sites of negligible concern and to remove them from further consideration with a high degree of confidence. In this paper we compare the screening assessment outputs of three freely available models. The outputs of these models varied considerably in terms of estimated risk quotient (RQ) and the radionuclide-organism combinations identified as being the most limiting. A number of factors are identified as contributing to this variability: values of transfer parameters (concentration ratios and Kd) used; organisms considered; different input options and how these are utilised in the assessment; assumptions as regards secular equilibrium; geometries and exposure scenarios. This large variation in RQ values between models means that the level of confidence required by users is not achieved. We recommend that the factors contributing to the variation in screening assessments be subjected to further investigation so that they can be more fully understood and assessors (and those reviewing assessment outputs) can better justify and evaluate the results obtained. © 2010 IOP Publishing Ltd.

Information has been complied on the fractional absorption of a range of radionuclides by adult domestic ruminants. Critical analysis of these data has enabled the derivation of recommended values for fractional absorption which will form part of the new handbook of parameter values for the prediction of radionuclide transfer in terrestrial and freshwater environments to be published by the International Atomic Energy Agency. Whilst most data considered were for caesium, strontium and iodine, values for 23 other radionuclides are also given. The recommended fractional absorption values are presented here, together with descriptions of the literature used to derive them. The values for domestic ruminants are compared with those derived by the International Commission for Radiological Protection for adult humans.

This paper presents the application of three publicly available biota dose assessment models (the ERICA Tool, RD128/SP1a and RESRAD-BIOTA) to an assessment of the Drigg coastal sand dunes. Using measured (90)Sr, (99)Tc, (137)Cs, (238)Pu, (239+240)Pu and (241)Am activity concentrations in sand dune soil, activity concentration and dose rate predictions are made for a range of organisms including amphibians, birds, invertebrates, mammals, reptiles, plants and fungi. Predicted biota activity concentrations are compared to measured data where available. The main source of variability in the model predictions is the transfer parameters used and it is concluded that developing the available transfer databases should be a focus of future research effort. The value of taking an informed user approach to investigate the way in which models may be expected to be applied in practice is highlighted and a strategy for the future development of intercomparison exercises is presented.

Databases have been compiled to derive parameter values relevant to the transfer of radionuclides from feedstuffs to domestic animal products to provide a revision to the IAEA Handbook on transfer parameters TRS 364. Significant new data inputs have been incorporated into the databases from an extensive review of Russian language information and inclusion of data published since the early 1990s. Fractional gastrointestinal absorption in adult ruminants presented in the revised handbook are generally similar to those recommended for adult humans by the ICRP. Transfer coefficient values are presented in the handbook for a range of radionuclides to farm animal products. For most animal products, transfer coefficient values for elements additional to those in TRS 364 are provided although many data gaps remain. Transfer coefficients generally vary between species with larger species having lower values than smaller species. It has been suggested that the difference is partly due to the inclusion of dietary dry matter intake in the estimation of transfer coefficient and that whilst dietary intake increases with size nutrient concentrations do not. An alternative approach to quantifying transfer by using concentration ratios (CR), which do not consider dietary intake, has been evaluated. CR values compiled for the handbook vary considerably less between species than transfer coefficient values. The advantage of the CR approach is that values derived for one species could be applied to species for which there are no data. However, transfer coefficients will continue to be used as few studies currently report CR values or give data from which they can be estimated.

Few data are available to quantify the transfer of both natural and anthropogenic radionuclides to detritivorous invertebrates to facilitate estimation of the internal dose to such biota in models used to assess radiation exposure. To enhance the available data, activity concentrations of (137)Cs, (40)K, (90)Sr, (239 + 240)Pu, (241)Am, (235)U and (238)U were measured in ants (Formicidae) and corresponding undisturbed soil collected from the Zlatibor mountain in Serbia and ant/soil concentration ratios (CR) calculated. The (241)Am concentration ratios for ants were fourfold higher than those calculated for ants in a previous study whereas they are similar to the more numerous data previously reported for a range of detritivorous invertebrates in other studies. CR values for (137)Cs in ants were similar to the few other reported values and slightly lower than those for a range of detritivorous invertebrates. Those for (239 + 240)Pu were slightly higher than those for ants in two other studies but they were close to upper limit of a range of data reported for detritivorous invertebrates. All the CR values will be included in a future revision of the ERICA Tool database and will particularly improve the information available for uranium.

Over 150 publications reporting studies conducted in the former USSR were reviewed to provide transfer coefficients (F(f)) to the muscle of domestic animals from experiments using chronic administration, often for long timescales in large scale experiments. Only a few of these studies were made available in the English language literature or taken into account in international reviews. The values derived have been compared with expected values reported by the IAEA's Handbook of parameter values for the prediction of radionuclide transfer in temperate environments (TRS 364) where possible. The information presented here has been used in the current updating of parameters recommended for environmental assessments by the IAEA. Many of the reported values are for Sr due to the Mayak accident and Cs due to the Chernobyl accident. Nevertheless, the reported data for a wide range of radionuclides, in particular for Ru, Sb, and Zn markedly improve the extent of available data.

There is general international acceptance of the need to demonstrate that the environment is protected from ionising radiation. In some countries requirements and guidelines for the protection of non-human biota are already in place. As a consequence a number of models and approaches have been proposed for the estimation of the exposure of non-human biota to ionising radiation. The IAEA EMRAS programme's Biota Working Group has conducted the most comprehensive intercomparison of the predictions of these approaches to date. In this paper, we present an overview of the activities of the Biota Working Group concentrating on its conclusions and recommendations.

An assessment of the natural radiation dose to wildlife in England and Wales was made to determine the contribution it may make to the total radiation dose estimated during environmental impact assessments. Significant use was made of systematic datasets for environmental media (stream sediments, stream waters and soils), in particular those produced by the Geochemical Baseline Survey of the Environment (G-BASE) project. This provided extensive, although variable, coverage for different elements and sample types after normalisation of data to account for changes in sampling and analysis over time. Almost complete coverage for K in stream sediments was achieved by merging G-BASE andWolfson Atlas data. This required normalisation of theWolfson data to the G-BASE results. Coverage was improved greatly for U and Th in sediments, and K, U and Th in soils, by using the strong relationship between soils and sediments and geology (both solid and superficial) to extrapolate the data. The total U, Th and K data were used to derive activity concentrations of 238U and 232Th series radionuclides and 40K. External dose rates to wildlife were then estimated from derived media concentrations; internal dose rates were estimated from measured activities in biota or activities predicted using recommended concentration ratios.

Assessments of radiation exposure of reptiles may be required in some countries as many species are protected. However, there are few data available for the transfer of radionuclides to them, especially in terrestrial ecosystems, and consequently, no specific peer reviewed reptile data have been used in the derivation of default transfer parameters in the ERICA Tool. Twenty samples of Lacerta agilis (sand lizard) and five of Natrix natrix (grass snake) were collected from two sites within the Chernobyl Exclusion Zone and analysed for Pu-isotopes, 137 Cs and 90 Sr. Corresponding activity concentrations for soil from the sampling sites were available. These data have been used to derive concentration ratios (CR) (i.e. reptile whole-body fresh weight activity concentration relative to the dry weight activity concentration in soil). CR values for N. natrix tended to be lower than those for L. agilis . The CR values derived in this paper will be used to improve the default values provided within the ERICA Tool. Whole-body activity concentrations determined in the reptile samples were broadly comparable with data available from the same sampling sites for small mammal species.

An essential step in the development of any modelling tool is the validation of its predictions. This paper describes a study conducted within the Chernobyl exclusion zone to acquire data to conduct an independent test of the predictions of the ERICA Tool which is designed for use in assessments of radiological risk to the environment. Small mammals were repeatedly trapped at three woodland sites between early July and mid-August 2005. Thermoluminescent dosimeters mounted on collars were fitted to Apodemus flavicollis, Clethrionomys glareolus and Microtus spp. to provide measurements of external dose rate. A total of 85 TLDs were recovered. All animals from which TLDs were recovered were live-monitored to determine (90)Sr and (137)Cs whole-body activity concentrations. A limited number of animals were also analysed to determine (239,240)Pu activity concentrations. Measurements of whole-body activity concentrations and dose rates recorded by the TLDs were compared to predictions of the ERICA-Tool. The predicted (90)Sr and (137)Cs mean activity concentrations were within an order of magnitude of the observed data means. Whilst there was some variation between sites in the agreement between measurements and predictions this was consistent with what would be expected from the differences in soil types at the sites. Given the uncertainties of conducting a study such as this, the agreement observed between the TLD results and the predicted external dose rates gives confidence to the predictions of the ERICA Tool.

A number of models have recently been, or are currently being, developed to enable the assessment of radiation doses from ionising radiation to non-human species. A key component of these models is the ability to predict whole-organism activity concentrations in a wide range of wildlife. In this paper, we compare the whole-organism activity concentrations predicted by eight models participating within the IAEA Environmental Modelling for Radiation Safety programme for a range of radionuclides to terrestrial and freshwater organisms. In many instances, there was considerable variation, ranging over orders of magnitude, between the predictions of the different models. Reasons for this variability (including methodology, data source and data availability) are identified and discussed. The active participation of groups responsible for the development of key models within this exercise is a useful step forward in providing the transparency in methodology and data provenance required for models which are either currently being used for regulatory purposes or which may be used in the future. The work reported in this paper, and supported by other findings, demonstrates that the largest contribution to variability between model predictions is the parameterisation of their transfer components. There is a clear need to focus efforts and provide authoritative compilations of those data which are available.

Following the Chernobyl accident in 1986, restrictions were placed on the movement and slaughter of sheep within upland areas of the UK because radiocaesium activity concentrations in their meat exceeded 1000 Bq kg(-1) fresh weight. Some farms remain under restriction in 2007. From 1991 to 1993 detailed studies were conducted on three sheep farms within the restricted area of west Cumbria to systematically assess the various parameters which may contribute to the observed variability in radiocaesium activity concentrations within sheep flocks. This paper reports the spatial variation in soil and vegetation activity concentrations across the grazed areas at these farms and determines the influence of grazing behaviour on variability in (137)Cs activity concentrations between individual sheep within the flocks. Together with previously reported results, these new data are used to draw conclusions on the factors determining variability within the three flocks. However, the factors are too site specific to be able to generalise the findings to other farms within the restricted areas of the UK.

Sulphur-35 is released during the routine operation of UK gas-cooled reactors. An experiment to determine the rates of transfer of different forms of (35)S to goat milk is described. Lactating goats received (35)S orally as single administrations of sulphate, L-methionine, or grass contaminated either through root uptake of (35)S as sulphate or through aerial deposition of (35)S as carbonyl sulphide onto the grass. Transfer was higher for (35)S administered as methionine compared with (35)S administered as sulphate. Changes in activity concentrations in milk for all sources of (35)S demonstrated two components of loss. The first component had a half-life of circa 1 d for all sources, the second was longer in goats administered carbonyl sulphide (44 d) than in all of the other treatments (circa 10 d). The rate of transfer of (35)S to milk of a further group of goats receiving (35)S-sulphate daily appeared to reach equilibrium within 30 d. Extrapolation of transfer parameters derived to other dairy ruminants is discussed.

A study to measure the transfer of radiocaesium to adult female sheep through a breeding cycle is described. The transfer of radiocaesium from the diet to muscle (estimated as the equilibrium transfer coefficient) was significantly lower to pregnant, and especially lactating, animals compared to non-lactating and barren animals. High dry matter intake rates were also associated with significantly lower transfer coefficients. Known relationships between dry matter intake rates and protein turnover could credibly explain some of these differences. However, when described as the concentration ratio, radiocaesium transfer to meat was apparently highest during lactation. The apparent difference in results obtained by the two approaches of determining transfer is the consequence of daily dry matter intake being a denominator within the estimation of transfer coefficient. A wider discussion of transfer coefficients and concentration ratios leads us to suggest that the concentration ratio is the more robust and potentially generic parameter.

A number of assessment frameworks have been proposed to provide a mechanism to demonstrate protection of the environment from ionising radiation. Whilst some of these are being used for assessment purposes they have largely not been validated against field measurements. In this paper we compare the predictions of transfer parameters recommended by one of these frameworks (FASSET) with observed whole-body 90Sr and radiocaesium activity concentrations in a range of mammal and invertebrate species sampled within the Chernobyl exclusion zone. Predicted activity concentrations were generally within the observed ranges and mean predictions for reference organisms were similar to, or circa one order of magnitude higher than, the observed means. However, some predictions were more than one order of magnitude lower than observed values. No data were available to test predictions for the other radionuclides released by the Chernobyl accident. In a separate paper the outputs of this assessment will be used to estimate doses to reference organisms and compare these to observed radiation induced effects reported within the Chernobyl zone.

We review collated data and available models for estimating the transfer of radionuclides to terrestrial biota within the European Arctic. The most abundant data are for radiocaesium and radiostrontium although many data for natural radionuclides are available. For some radionuclides no data are available for describing transfer to Arctic biota. Allometric-kinetic models have been used to estimate transfer for radionuclide-biota combinations. Predicted values were in good agreement with observed data for some radionuclides although less so for others. There are no bespoke models to enable the dynamic prediction of radionuclide transfer to Arctic biota. A human Arctic foodchain model has been adapted to estimate 137 Cs and 90 Sr transfer to some Arctic biota. There are many factors of Arctic ecosystems which may influence radionuclide behaviour including short growing seasons, prolonged soil freezing, and effects of low temperatures on biological rates. If exposure to ionising radiation in Arctic ecosystems is to be robustly predicted such factors must be fully understood and incorporated into models.

A number of frameworks have been proposed to assess the protection of wildlife from ionising radiations. In this paper we compare the predictions of transfer parameters recommended by one of these frameworks (FASSET) with observed whole-body 90 Sr and 137 Cs activity concentrations in a range of mammal and invertebrate species sampled within the Chernobyl exclusion zone. Predicted activity concentrations are generally within the observed ranges and mean predictions for reference organisms are similar to, or circa one order of magnitude higher than, the observed means. However, some predictions are more than one order of magnitude lower than observed values. No data were available for animals to test predictions for the other radionuclides released by the Chernobyl accident. In a separate paper the outputs of this assessment will be used to estimate doses to reference organisms and compare these to observed radiation induced effects reported within the Chernobyl zone.

Assessment of the transfer of radionuclides to wild species is an important component in the estimation of predicted doses to biota. Reviews of available data for the many potential radionuclide-biota combinations which may be required for environmental assessments highlight many data gaps for terrestrial species. Here, we discuss different approaches which have been suggested to compensate for these data gaps. All of the reviewed approaches have merit; however, there is a requirement for transparency in methodology and data provenance which in some instances is currently missing. Furthermore, there is a need to validate the various methodologies to enable their use with confidence. The requirements of improving our ability to predict radionuclide transfer to wild species are discussed and recommendations made.

We have previously demonstrated a relationship between dry matter (DM) intake and the degree of transfer of radiocaesium to the muscle of adult sheep. Here, we present the results of an experiment during which we examined the effect of lamb growth and protein turnover rates, brought about by controlling feed DM intakes, on radiocaesium transfer and turnover. Lambs with high DM intakes and, as a consequence, high rates of growth, had a lower mean radiocaesium transfer coefficient from the diet to muscle than lambs with lower intake and growth rates. Furthermore, high rates of dry matter intake decreased the biological half-life of radiocaesium from muscle. The administration of [3%]-ntethionine to the study lambs enables us to suggest that radiocaesium transfer may be related to protein turnover. When the results were compared with those of other studies using sheep, a consistent relationship between DM intake and radiocaesium transfer across all animals regardless of age or physiological status was observed. Extrapolation of the relationship to DM intake rates appropriate to cattle predict radiocaesium transfer coefficients in broad agreement with reported values.

A recently developed semi-mechanistic temporal model is used to predict food product radiocaesium activity concentrations using soil characteristics available from spatial soil databases (exchangeable K, pH, percentage clay and percentage organic matter content). A raster database of soil characteristics, radiocaesium deposition, and crop production data has been developed for England and Wales and used to predict the spatial and temporal pattern of food product radiocaesium activity concentrations (Bq/kg). By combining these predictions with spatial data for agricultural production, an area's output of radiocaesium can also be estimated, we term this flux (Bq/year per unit area). Model predictions have been compared to observed data for radiocaesium contamination of cow milk in regions of England and Wales which received relatively high levels of fallout from the 1986 Chernobyl accident (Gwynedd and Cumbria). The model accounts for 56% and 80% of the observed variation in cow milk activity concentration for Gwynedd and Cumbria, respectively. Illustrative spatial results are presented and suggest that in terms of food product contamination areas in the North and West of England and Wales are those most vulnerable to radiocaesium deposition. When vulnerability is assessed using flux the spatial pattern is more complex and depends upon food product.

In the years following the Chernobyl accident the consumption of wild fungi has been shown to contribute significantly to the radiocaesium intake of humans in several countries. However, in Great Britain, the collection of wild fungi for consumption has generally been thought to be of minor importance and the pathway has not been considered in assessment of radioactivity to humans. The study reported here provides information on contamination levels and consumption rates of wild fungi. To gather the information required, two concurrent surveys were conducted. The first assessed the radiocaesium contamination levels present in commonly eaten fungal species where samples of wild fungi were collected from mainland Great Britain (in collaboration with the British Mycological Society's affiliated Fungus Groups). The second was a survey of consumption habits. The results show that it is not the actual amount of fungi consumed by individuals which determines their radiocaesium intake, but rather the species they select; mycorrhizal species, for example, have significantly greater 137 Cs activity concentrations than saprotrophic and parasitic species. It is concluded that the consumption of wild fungi would not currently be expected to appreciably increase the intake of radioactivity of most consumers above that attributable to the normal diet.

The potential of using different alginates or supplementary calcium as feed-additives to reduce the transfer of ingested radiostrontium to milk was assessed in dairy cattle fed a haylage/concentrate diet. The feed-additives compared were: calcium alginate (4% by dry matter), sodium alginate (4% by dry matter) and four levels of supplementation with CaCO3. Both alginates reduced the transfer of radiostrontium to milk by 30–40% without effecting diet palatability. However, the high present cost of alginates precludes their use as countermeasures. Dietary calcium supplementation reduced the transfer of 85 Sr to milk broadly in agreement with previous predictions. From data relevant to dairy cattle in the United Kingdom it is suggested that dietary calcium intake could be doubled without exceeding recommended maximum intakes, thus decreasing the transfer of radiostrontium to milk by approximately 50%.

The transfer of radioactivity to the milk and meat of farm animals is likely be a major exposure pathway of human populations, following an environmental release of radioactivity. The importance of source-dependent bioavailability in determining absorption from the ruminant gastrointestinal tract of the radiologically significant radionuclides (radiocesium, radiostrontium, radioiodine, and plutonium) is reviewed. The requirements for and suitability of in vitro methods of determining bioavailability for absorption of these radionuclides is also assessed. Radiocesium absorption varies over a 50-fold range, depending upon dietary source. Source-dependent bioavailability is therefore an important factor in determining the radiocesium contamination of ruminant-derived food products, and reliable in vitro techniques have been developed to rapidly determine its bioavailability. In contrast, under conditions of adequate calcium intake, the absorption of radiostrontium will not be greatly influenced by the dietary source. Results of in vitro extractions of radiostrontium could be misleading, as they indicate differences in bioavailability that are not observed in the animal. Absorption of radioiodine is complete and independent of source. There is currently a lack of data on plutonium absorption in ruminants. However, on the basis of the limited data available, in vitro incubations provide a measure of the relative bioavailabilities of plutonium from different sources. The applicability of the techniques reviewed to the study of other radionuclides and heavy metals is discussed.

The accident at the Chernobyl nuclear power plant in 1986 resulted in levels of radiocaesium in animal-derived food products above national intervention limits in a number of countries. In upland areas of the United Kingdom (UK) radiocaesium activity concentrations in the meat of some sheep exceeds (in 1998) the local intervention limit of 1000 Bq kg−1 and measures are still in place to restrict the entry of such animals into the human food chain. The use of many established countermeasure techniques is difficult due to the nature of animal management in the affected areas. This paper describes a study to develop and test a bolus containing the radiocaesium binder ammonium ferric hexacyanoferrate (AFCF) suitable for administration to small lambs of hill-sheep breeds used in the UK. It was found that a bolus 14 mm × 50 mm in size, and containing 20% AFCF, could be safely administered to lambs of 10 kg. An increase in the AFCF content above 20% resulted in too rapid a breakdown of the bolus. Administration of three boli per lamb reduced the 137 Cs activity concentration in muscle by circa 50% between 3 and 8 weeks following administration of the boli. After 12 weeks the reduction in the 137 Cs activity concentration was 30%. We conclude that the AFCF bolus developed could be effectively used to reduce the radiocaesium activity concentration in lambs within hill and upland areas of the UK.

Toxic heavy metals such as cadmium and mercury can enter the diet of farm animals by a variety of environmental exposure routes and, hence, contaminate food products derived from those animals. Therefore, there is a need to be able to predict the likely levels of contamination in animal tissues if exposed to a contaminated diet and also to estimate how rapidly an animal will decontaminate once the source of contamination is removed from the diet. Data on the transfer and excretion rates of Cd and Hg from tissues have previously been inadequate to allow the development of dynamic models to predict changes in the degree of contamination of different tissues of ruminants. A study is described during which a group of sheep were given a single oral administration of 109Cd and 203Hg. Measurements of the concentrations of the radioisotopes in tissue samples were subsequently made over a period of 1 year. The resultant data were used to develop compartment models to describe the behavior of the two metals in sheep tissues. To our knowledge the models developed are the first to allow the time-dependent prediction of the potential Cd and Hg contamination of animal-derived food products. Previously only advised transfer coefficients were available; we demonstrate that these are of little value for cadmium and mercury due to their slow rates of accumulation and excretion.

Ingestion of milk contaminated by radioiodine (most especially 131 I) represents an important potential route of radiation exposure to humans in the event of a nuclear accident. Oral administration of stable iodine to dairy ruminants has previously been suggested as an effective countermeasure to reduce radioiodine levels in milk. However, previous data on its effectiveness are contradictory, and little attention has been given to the most appropriate time to administer stable iodine relative to the time that an animal is first exposed to radioiodine. The effectiveness of 1g KI orally administered to lactating goats 12 h before and 12 h after contamination with pulse doses of radioiodine was investigated. Administration of KI prior to the ingestion of radioiodine was shown to reduce the transfer to milk by 50% compared to a reduction of approximately 40% when KI was administered 12 h after radioiodine. The administration of KI 12 h prior to radioiodine contamination effectively reduced the transfer of radioiodine to the thyroid by approximately 90%. When administered 12 h after radioiodine, the KI stopped subsequent uptake of radioiodine by the thyroid. The maximum level of iodine in milk, as a consequence of the administration of KI, was 20 mg I kg −1 . This was 40-fold higher than the maximum permissible level of iodine in milk of 0.5 mg l −1 currently set in some countries. Further consideration is required on stable iodine administration regimes for different scenarios and the consequent increase in the stable iodine content of the milk of different dairy animals.

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 (CR wo-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 CR wo-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 CR wo-water values for freshwater species currently available for use in radiological environmental assessments.

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.

The validity of an in vitro extraction technique to predict the availability for absorption of radiocaesium in the sheep gut has been assessed. The technique (a 2-h extraction with caesium chloride) was found to be valid for sources with a low availability for transfer across the gut, but inappropriate for ionic radiocaesium or radiocaesium incorporated internally within herbage. For such radiocaesium sources, which have a high in vitro availability, no correlation was found between in vitro extraction and true absorption measurements. A true absorption value of 0.80 is recommended for these sources, although values for individual sheep in the range 0.60 to 1.00 should be expected.

International audience; 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). © 2012 Elsevier Ltd.

Estimates of absorbed dose rates to wildlife from exposure to natural background radionuclides are required to put estimates of dose rates arising from regulated releases of radioactivity and proposed benchmarks into context. Recent review papers have estimated dose rates to wildlife from (40)K, and (238)U and (232)Th series radionuclides. However, only one study previous has considered the potential dose rates to burrowing animals from inhaled (222)Rn and its daughter products. In this paper we describe a study conducted at seven sites in northwest England. Passive track etch detectors were used to measure the (222)Rn concentrations in artificial burrows over a period of approximately one year. Results suggest that absorbed dose rates to burrowing mammals as a consequence of exposure to (222)Rn are likely to be at least an order of magnitude higher than those suggested in previous evaluations of natural background exposure rates which had omitted this radionuclide and exposure pathway. Dose rates in some areas of Great Britain will be considerably in excess of incremental no-effects benchmark dose rates suggested for use as screening levels. Such advised benchmark dose rates need to be better put into context with background dose rates, including exposure to (222)Rn, to ensure credibility; although the context will be determined by the purpose of the benchmark and the assessment level.

An IAEA handbook presenting transfer parameter values for wildlife has recently been produced. Concentration ratios (CRwo-media) between the whole organism (fresh weight) and either soil (dry weight) or water were collated for a range of wildlife groups (classified taxonomically and by feeding strategy) in terrestrial, freshwater, marine and brackish generic ecosystems. The data have been compiled in an on line database, which will continue to be updated in the future providing the basis for subsequent revision of the Wildlife TRS values. An overview of the compilation and analysis, and discussion of the extent and limitations of the data is presented. Example comparisons of the CRwo-media values are given for polonium across all wildlife groups and ecosystems and for molluscs for all radionuclides. The CRwo-media values have also been compared with those currently used in the ERICA Tool which represented the most complete published database for wildlife transfer values prior to this work. The use of CRwo-media values is a pragmatic approach to predicting radionuclide activity concentrations in wildlife and is similar to that used for screening assessments for the human food chain. The CRwo-media values are most suitable for a screening application where there are several conservative assumptions built into the models which will, to varying extents, compensate for the variable data quality and quantity, and associated uncertainty. © 2012 Elsevier Ltd.

It is difficult to measure transfer of radiocaesium to the tissues of forest ruminants because they can potentially ingest a wide range of plant types. Measurements on undomesticated forest ruminants incur further difficulties. Existing techniques of estimating radiocaesium intake are imprecise when applied to forest systems. New approaches to measure this parameter are discussed. Two methods of intake estimation are described and evaluated. In the first method, radiocaesium intake is estimated from the radiocaesium activity concentrations of plants, combined with estimates of dry-matter (DM) intake and plant species composition of the diet, using plant and orally-dosed hydrocarbons (n-alkanes) as markers. The second approach estimates the total radiocaesium intake of an animal from the rate of excretion of radiocaesium in the faeces and an assumed value for the apparent absorption coefficient. Estimates of radiocaesium intake, using these approaches, in lactating goats and adult sheep were used to calculate transfer coefficients for milk and muscle; these compared favourably with transfer coefficients previously obtained under controlled experimental conditions. Potential variations in bioavailability of dietary radiocaesium sources to forest ruminants have rarely been considered. Approaches that can be used to describe bioavailability, including the true absorption coefficient and in vitro extractability, are outlined.