Progress on the Development of Parameter Progress on the Development of Parameter Values for Reference Animals and Plants Values for Reference Animals and Plants IAEA EMRAS II Transfer Group IAEA EMRAS II Transfer Group Vienna, Austria, 25- Vienna, Austria, 25 -29 January 2010 29 January 2010 T.L. Yankovich T.L. Yankovich AREVA Resources Canada AREVA Resources Canada tamara.yankovich@AREVA.ca AREVA.ca tamara.yankovich@ Interactions and Chemical Exchange between Organisms and their Environment Concentration of Radionuclide in Concentration of Radionuclide in the Immediate Environment the Immediate Environment Air Air Soil Soil Vegetation Vegetation Water Water Sediments Sediments Metabolic models, Metabolic models, Intake of Intake of absorbtion models, absorbtion models, radionuclide radionuclide etc. etc. Radionuclide Radionuclide concentration in concentration in whole organism whole organism Internal Internal radionuclide radionuclide partitioning partitioning Compartment size, Compartment size, geometry, composition, geometry, composition, Concentration in Concentration in Organ-specific Organ-specific etc. etc. reference organ reference organ radionuclide radionuclide concentration concentration Internal Compartmentalization Internal Compartmentalization Compartment-specific dose Compartment-specific dose (Compartment Identification) (Compartment Identification) Information on Information on Effect(s) of Effect(s) of effects on critical effects on critical radionuclide radionuclide endpoints of dose endpoints of dose intake and intake and to a given organ to a given organ concentration concentration 1
Where . . . Where . . . Doses to non-human biota (“wildlife”) are typically predicted on a whole-body basis. However, depending on the purpose of a given study, tissue-specific measurements may be taken, as opposed to those for the whole body. (e.g., those for edible tissues in monitoring programs designed to assess radionuclide transfer to humans). Specifically, How do we use tissue-specific data to estimate whole-body values given the internal complexity of an organism? Brain Brain Liver Liver Heart Heart Scales Scales Swim Swim Bladder Bladder Kidney Kidney Bone Bone Muscle Muscle e.g., the potential complexity of a fish 2
To Address this Question . . . To Address this Question . . . • An organism can be assessed using a mass balance approach (e.g., Yankovich, 2009) . • In doing so, data on compartment sizes and the internal partitioning of radionuclides in a given tissue relative to a “reference tissue” could be used. With this in Mind . . . With this in Mind . . . Efforts have been undertaken to Efforts have been undertaken to compile available data on internal compile available data on internal partitioning of radionuclides and stable partitioning of radionuclides and stable analogues in animal tissues. analogues in animal tissues. 3
Where the Purpose was . . . Where the Purpose was . . . To estimate whole- -body body To estimate whole radionuclide concentrations radionuclide concentrations based on measurements taken based on measurements taken for specific tissues. for specific tissues. Data Requirements: Data Requirements: Measurements taken at under steady state conditions. Realistic exposure conditions for laboratory experiments. Concentration data for at least two tissues or for one tissue plus whole-body. Tissue mass data for at least one tissue plus whole-body. Measurements taken for the same organism or group of organisms. 4
Scope of Compilation: Scope of Compilation: Radionuclides of stable elements. Freshwater, marine and terrestrial ecosystems. Wild and domesticated vertebrates and invertebrates. Whole-body, muscle, bone, liver, kidney and gonad tissues. Where possible, animals were categorized by IAEA ‘wildlife’ category. Outcome . . . Outcome . . . An estimation of whole- -body body An estimation of whole radionuclide (or stable analogue) radionuclide (or stable analogue) concentrations based on measurements concentrations based on measurements taken for specific animal tissues. taken for specific animal tissues. 5
To Date… ….. .. To Date Focus has been placed on developing Focus has been placed on developing conversion factors for animals, with conversion factors for animals, with the intent to switch focus to plants, the intent to switch focus to plants, once complete. once complete. Compilation of Compartment Size Compilation of Compartment Size 6
Compilation of Internal Partitioning Data Compilation of Internal Partitioning Data Based on this Analysis: Based on this Analysis: Similarities between groups of elements have been used to estimate expected internal partitioning patterns within an organism. 7
Summary of Collated Data: Animals Summary of Collated Data: Animals Simplifying Reference Fish: Defining Chemically-Distinct Compartments Bone Seekers Non-Bone Seekers Divalent Elements in Univalent Elements in Mature Northern Pike Mature Northern Pike 100 1000 C(organ)/C(reference organ) C(organ)/C(reference organ) 100 10 10 1 1 0.1 0.1 Ba Ca Mg Sr Cs K Na Rb Element Element Reference Organ Reference Organ blood blood bone bone kidney kidney liver liver gonads gonads B r a i n B r a i n L i v e r L i v e r H e a r t H e a r t S c a l e s S c a l e s S w i m S w i m B l a d d e r B l a d d e r K i d n e y K i d n e y B o n e B o n e M u s c l e M u s c l e It appears that compartmentalization of fishes and frogs can be simplified based on the partitioning patterns of a given element.. Conceptual Model I: Conceptual Model II: Whole Whole Fish Fish ST ST B B Sc Sc 8
Work is Available on This . . . . . Work is Available on This . . . . . Yankovich, 2009. Mass balance approach to Mass balance approach to Yankovich, 2009. estimating radionuclide loads and concentrations estimating radionuclide loads and concentrations in edible fish tissues using stable analogues. in edible fish tissues using stable analogues. Journal of Environmental Journal of Environmental Radiactivity Radiactivity, , doi:10.1016/ j.jenvrad.2009.05.001 doi:10.1016/ j.jenvrad.2009.05.001. . (from the EMRAS I (from the EMRAS I update of I AEA TRS 364) update of I AEA TRS 364) … from a human perspective. Summary of Outcome: Animals Summary of Outcome: Animals A series of look-up tables with tissue-to-whole body for radionuclides and stable isotopes in the specified animal categories. As context, tables containing the % biomasses of specified tissues with respect to the whole-body biomass have been compiled. Data are also available on tissue water contents, ash contents, % C contents. 9
Summary of Findings for Summary of Findings for Reference Plant Reference Plant Similar Work is Underway for Plants Similar Work is Underway for Plants It seems possible to develop conversion 10 factors for plants, as C(organ)/C(reference organ) well. With relatively 1 consistent patterns occurring for similar types of elements. 0.1 Ba Ca Mg Sr Element A key question is how to Reference Organ compartmentalize the stems fruit roots plant. 10
Conceptual Models of Reference Plant Group 2: Group 1: Whole Whole Group 3: Plant Plant F L AG AG ST BG BG R Status Summary: Status Summary: Look up tables have been generated for marine fish, mammals, birds reptiles and amphibians (freshwater fish tables to be finalized this week). Based on these data, a paper has been drafted for submission as part of a special edition. Input of data has been received from UK, Japan, Norway, Sweden, Australia and Canada. Work is underway to compile data on plants (participation welcome!) 11
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