A new IAEA Technical Report Series Handbook on Radionuclide Transfer to Wildlife

The IAEA Technical Report Series (TRS) handbook on transfer of radionuclides to human foodstuffs from terrestrial and freshwater systems has recently been revised during the EMRAS I programme [1]. The document updates the previous handbook (TRS 364) and constitutes an important source of information for transfer parameters for the human foodchain. Quantification of the rates of transfer of radionuclides through foodchains to humans has long been a key focus of radiation protection. More recently, there has been a move away from radiation protection being solely anthropogenic to one which also considers protection of the environment as recognised by both the IAEA [2] and the ICRP [3] in their Fundamental Safety Principles and revised Recommendations, respectively, both of which now include the need to protect the environment. To address these recommendations and safety principles, the consequences of radiological releases need to be considered in part by estimating an internal dose. To do this, the transfer of radionuclides to wildlife of interest needs to be quantified. In response to the need for a reference source of information on radionuclide transfer to wildlife, the IAEA initiated the development of a TRS handbook, which has been supported by interaction with the EMRAS II Working Group 5, (http://www-ns.iaea.org/projects/emras/emras2/working-groups/working-group-five.asp). The TRS handbook has been finalised and is currently going through the IAEA approval process. The TRS handbook provides equilibrium concentration ratio values for wildlife groups in terrestrial, freshwater, marine and estuarine environments. Wildlife is considered to include all non-domesticated plants, animals and other organisms including feral species (i.e. non-native self-sustaining populations). The TRS handbook provides IAEA Member States with transfer data for use in the radiological assessment of wildlife as a consequence of planned and existing exposure situations [3]. As an equilibrium approach is presented, these data are not directly applicable to emergency situations

Derivation of transfer parameters for use within the ERICA Tool and the default concentration ratios for terrestrial biota

An ability to predict radionuclide activity concentrations in biota is a requirement of any method assessing the exposure of biota to ionising radiation. Within the ERICA Tool fresh weight whole-body activity concentrations in organisms are estimated using concentration ratios (the ratio of the activity concentration in the organism to the activity concentration in an environmental media). This paper describes the methodology used to derive the default terrestrial ecosystem concentration ratio database available within the ERICA Tool and provides details of the provenance of each value for terrestrial reference organisms. As the ERICA Tool considers 13 terrestrial reference organisms and the radioisotopes of 31 elements, a total of 403 concentration ratios were required for terrestrial reference organisms. Of these, 129 could be derived from literature review. The approaches taken for selecting the remaining values are described. These included, for example, assuming values for similar reference organisms and/or biogeochemically similar elements, and various simple modelling approaches

The IAEA handbook on radionuclide transfer to wildlife

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.Additional co-authors: H Takata, P Andersson, P Dale, J Ryan, A Bollhöfer, C Doering, CL Barnett, C Well