ANSTO :: Browsing by Author "Davis, E"

Browsing by Author "Davis, E"

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Accumulation of plutonium in mammalian wildlife tissues following dispersal by accidental-release tests
(Elsevier, 2016-01-01) Johansen, MP; Child, DP; Caffrey, EA; Harrison, JJ; Hotchkis, MAC; Payne, TE; Ikeda-Ohno, A; Thiruvoth, S; Beresford, NA; Twining, JR; Davis, E
We examined the distribution of plutonium (Pu) in the tissues of mammalian wildlife inhabiting the relatively undisturbed, semi-arid former Taranaki weapons test site, Maralinga, Australia. The accumulation of absorbed Pu was highest in the skeleton (83% ± 6%), followed by muscle (10% ± 9%), liver (6% ± 6%), kidneys (0.6% ± 0.4%), and blood (0.2%). Pu activity concentrations in lung tissues were elevated relative to the body average. Foetal transfer was higher in the wildlife data than in previous laboratory studies. The amount of Pu in the gastrointestinal tract was highly elevated relative to that absorbed within the body, potentially increasing transfer of Pu to wildlife and human consumers that may ingest gastrointestinal tract organs. The Pu distribution in the Maralinga mammalian wildlife generally aligns with previous studies related to environmental exposure (e.g. Pu in humans from worldwide fallout), but contrasts with the partitioning models that have traditionally been used for human worker-protection purposes (approximately equal deposition in bone and liver) which appear to under-predict the skeletal accumulation in environmental exposure conditions. © 2015, Elsevier Ltd.
Accumulation of plutonium in mammalian wildlife tissues: comparison of recent data with the ICRP distribution models
(International Conference on Radioecology and Environmental Radioactivity, 2014-07-01) Johansen, MP; Child, DP; Davis, E; Hotchkis, MAC; Payne, TE; Ikeda-Ohno, A; Twining, JR
We examined the distribution of plutonium (Pu) in the tissues of mammalian wildlife to address the paucity of such data under environmental exposure conditions. Pu activity concentrations were measured in Macropus rufus (red kangaroo), Oryctolagus cuniculus (European rabbit), and Pseudomys hermannsburgensis (sandy inland mouse)inhabiting the relatively undisturbed, semi-arid conditions at the former Taranaki weapons test site at Maralinga, Australia. Of the absorbed Pu (distributed via circulatory and lymph systems) accumulation was foremost in bone (83% ±10% SD), followed by muscle (9% ±10%), liver (7% ±7%), kidneys (0.5% ±0.3%), and heart (0.4% ±0.4%). The bone values are higher than those reported in ICRP 19 and 48 (45-50% bone), while the liver values are lower than ICRP values (30-45% liver). The ICRP values were based on data dominated by relatively soluble forms of Pu, including prepared solutions and single-atom ions produced by decay following the volatilisation of uranium during nuclear detonation (fallout Pu, ICRP 1986). In contrast, the Maralinga data relates to low-soluble forms of Pu used in tests designed to simulate accidental release and dispersal. We measured Pu in lung, GI-tract and the skin and fur as distinct from the absorbed Pu in bone, liver, muscle, and kidneys. Compared with the mean absorbed activity concentrations, the results for lung tissues were higher by up to one order of magnitude, and those in the GI tract contents and the washed skin/fur were higher by more than two orders of magnitude. These elevated levels are consistent with the presence of low-soluble Pu, including particulate forms, which pass through, or adhere upon, certain organs, but are not readily absorbed into the bloodstream. This more transitory Pu can provide dose to the lung and GI tract organs, as well as provide potential transfer of contamination when consumed in predator-prey food chains, or during human foodstuff consumption. For example, activity concentrations in O. cuniculus edible samples prepared according to traditional aboriginal methods were more than two orders of magnitude higher than in muscle alone. The increase was due to inclusion of GI tract components and contents in the traditional method. Our results provide new insights into the sequestration of Pu in mammalian tissues under environmental exposure conditions. These results contrast with those related to the specific forms of Pu and exposure conditions upon which the ICRP models were based. However, they provide data relevant to the assessment of key environmental legacy waste sites, and of potential release scenarios for the low-soluble oxide forms in the growing worldwide inventory of Pu associated with power production.
Diet-tissue discrimination of δ13C and δ15N in freshwater crustacean
(University of Western Australia, 2013-07-10) Mazumder, D; Johansen, MP; Davis, E
Knowledge and understanding of discrimination factors (d13C and d15N) for carbon-13(d13C) and nitrogen-15 (d15N) are important when using stable isotopes for trophodynamic studies. We performed a controlled laboratory diet-switch experiment to examine diet–tissue discrimination factors for muscle, carapace and stomach tissues of freshwater crustacean, Cherax destructor. A range of diets of differing d13C and d15N isotopic values were fed to C. destructor until equilibrium. For the various tissue types, d15N discrimination was highest in muscle, followed by carapace then stomach, whilst d13C was highest in carapace followed by stomach, then muscle. The resulting diet–muscle discrimination factors were similar to, but varied from the 1‰ for d13C and 3.4‰ for and d15N values that are often used for diet-muscle discrimination. The results highlight variation among differing diet types, and consumer tissue types as applied to stable carbon and nitrogen isotopes in the food-web studies.
Fluorine-18 radiolabelling and in vitro / in vivo metabolism of [18F]D4-PBR111
(John Wiley & Sons, Inc, 2019-05-26) Wyatt, NA; Safavi-Naeini, M; Wotherspoon, ATL; Arthur, A; Nguyen, AP; Parmar, A; Hamze, H; Day, CM; Zahra, D; Matesic, L; Davis, E; Rahardjo, GL; Yepuri, NR; Shepherd, R; Murphy, RB; Pham, TQ; Nguyen, VH; Callaghan, PD; Holden, PJ; Grégoire, MC; Darwish, TA; Fraser, BH
Objectives The purinergic receptor P2X ligand-gated ion channel type 7 (P2X7R) is an adenosine triphosphate (ATP)-gated ion-channel, and P2X7R is a key player in inflammation. P2X7R is an emerging therapeutic target in central nervous system (CNS) diseases including Alzheimer's disease (AD) and Parkinson's disease (PD), because P2X7R also plays a pivotal role in neuroinflammation. P2X7R represents a potential molecular imaging target for neuroinflammation via biomedical imaging technique positron emission tomography (PET), and several radioligands targeting P2X7R have been developed and evaluated in animals. In our previous work, we have developed and characterized [11C]GSK1482160 as a P2X7R radioligand for neuroinflammation,2 clinical evaluation of [11C]GSK1482160 in healthy controls and patients is currently underway, and the estimation of radiation dosimetry for [11C]GSK1482160 in normal human subjects has been reported.3 Since the half-life (t1/2) of radionuclide carbon-11 is only 20.4 min, it is attractive for us to develop derivatives of [11C]GSK1482160, which can be labeled with the radionuclide fluorine-18 (t1/2, 109.7 min), and a fluorine-18 ligand would be ideal for widespread use.4 To this end, a series of [18F]fluoroalkyl including [18F]fluoromethyl (FM), [18F]fluoroethyl (FE), and [18F]fluoropropyl (FP) derivatives of GSK1482160 have been prepared and examined as new potential P2X7R radioligands. © 2019 The Authors
Mitochondrial translocator protein (TSPO) expression in the brain after whole body gamma irradiation
(Frontier Media S.A., 2021-10-25) Betlazar, C; Middleton, RJ; Howell, NR; Storer, B; Davis, E; Davies, JB; Banati, RB; Liu, GJ
The brain’s early response to low dose ionizing radiation, as may be encountered during diagnostic procedures and space exploration, is not yet fully characterized. In the brain parenchyma, the mitochondrial translocator protein (TSPO) is constitutively expressed at low levels by endothelial cells, and can therefore be used to assess the integrity of the brain’s vasculature. At the same time, the inducible expression of TSPO in activated microglia, the brain’s intrinsic immune cells, is a regularly observed early indicator of subtle or incipient brain pathology. Here, we explored the use of TSPO as a biomarker of brain tissue injury following whole body irradiation. Post-radiation responses were measured in C57BL/6 wild type (Tspo+/+) and TSPO knockout (Tspo–/–) mice 48 h after single whole body gamma irradiations with low doses 0, 0.01, and 0.1 Gy and a high dose of 2 Gy. Additionally, post-radiation responses of primary microglial cell cultures were measured at 1, 4, 24, and 48 h at an irradiation dose range of 0 Gy-2 Gy. TSPO mRNA and protein expression in the brain showed a decreased trend after 0.01 Gy relative to sham-irradiated controls, but remained unchanged after higher doses. Immunohistochemistry confirmed subtle decreases in TSPO expression after 0.01 Gy in vascular endothelial cells of the hippocampal region and in ependymal cells, with no detectable changes following higher doses. Cytokine concentrations in plasma after whole body irradiation showed differential changes in IL-6 and IL-10 with some variations between Tspo–/– and Tspo+/+ animals. The in vitro measurements of TSPO in primary microglial cell cultures showed a significant reduction 1 h after low dose irradiation (0.01 Gy). In summary, acute low and high doses of gamma irradiation up to 2 Gy reduced TSPO expression in the brain’s vascular compartment without de novo induction of TSPO expression in parenchymal microglia, while TSPO expression in directly irradiated, isolated, and thus highly activated microglia, too, was reduced after low dose irradiation. The potential link between TSPO, its role in mitochondrial energy metabolism and the selective radiation sensitivity, notably of cells with constitutive TSPO expression such as vascular endothelial cells, merits further exploration. © The Authors - Open Access
Muscle and carapace tissue–diet isotope discrimination factors for the freshwater crayfish Cherax destructor
(CSIRO Publishing, 2017-09-08) Mazumder, D; Johansen, MP; Fry, B; Davis, E
This study examined a range of diets and two tissue types (muscle and carapace, representing protein and chitin biochemistry respectively) of Cherax destructor (Clark, 1936) to allow more accurate use of isotope data in trophic source estimates. The resulting Δ13Ctissue–diet and Δ15Ntissue–diet discrimination factors of muscle and carapace tissues showed significant differences among diets. For muscle, Δ13Ctissue–diet was higher (2.11–2.33‰) when C. destructor was fed with lamb, turkey and mixed animal and plant-based diets, 1.27–1.96‰ when C. destructor was fed with beef and kangaroo diets and negative (–1.36‰) when C. destructor was fed with an aquatic meat (tuna) diet. The Δ15Ntissue–diet discrimination factors were lower for muscle when C. destructor was fed aquatic meat (0.12‰) and mixed plant–animal diets (1.67‰), but higher for terrestrial meat diets (2.79–3.74‰). The Δ13Ctissue–diet for carapace followed similar patterns to that of muscle, but Δ15Ntissue–diet values were lower for carapace than muscle. Strong correlations were observed between muscle and carapace for δ13C (r = 0.96, P < 0.0001) and δ15N (r = 0.82, P < 0.0012) across the six diets evaluated, indicating that carapace can be used as a non-lethal alternative to muscle during field sampling. © CSIRO 2017
Plutonium in wildlife and soils at the Maralinga legacy site: persistence over decadal time scales
(Elsevier Science Ltd, 2014-05-01) Johansen, MP; Child, DP; Davis, E; Doering, C; Harrison, JJ; Hotchkis, MAC; Payne, TE; Thiruvoth, S; Twining, JR; Wood, MD
The mobility of plutonium (Pu) in soils, and its uptake into a range of wildlife, were examined using recent and similar to 25 year old data from the Taranaki area of the former Maralinga weapons test site, Australia. Since its initial deposition in the early 1960s, the dispersed Pu has been incorporated into the soil profile and food chain through natural processes, allowing for the study of Pu sequestration and dynamics in relatively undisturbed semi-arid conditions. The data indicate downward mobility of Pu in soil at rates of similar to 0.2-0.3 cm per year for the most mobile fraction. As a result, while all of the Pu was initially deposited on the ground surface, approximately 93% and 62% remained in the top 0-2 cm depth after 25- and 50-years respectively. No large-scale lateral spreading of the Taranaki plume was observed. Pu activity concentrations in 0-1 cm soils with biotic crusts were not elevated when compared with nearby bare soils, although a small number of individual data suggest retention of Pu-containing particles may be occurring in some biotic crusts. Soil-to-animal transfer, as measured by concentration ratios (CRwo-soil), was 4.1E-04 (Geometric Mean (GM)) in mammals, which aligns well with those from similar species and conditions (such as the Nevada Test Site, US), but are lower than the GM of the international mammal data reported in the Wildlife Transfer Database (WTD). These lower values are likely due to the presence of a low-soluble, particulate form of the Pu in Maralinga soils. Arthropod concentration ratios (3.1E-03 GM), were similar to those from Rocky Flats, US, while values for reptiles (2.0E-02 GM) were higher than the WTD GM value which was dominated by data from Chernobyl. Comparison of uptake data spanning approximately 30 years indicates no decrease over time for mammals, and a potential increase for reptiles. The results confirm the persistence of bioavailable Pu after more than 50 years since deposition, and also the presence of larger-sized particles which currently affect CRwo-soil calculations, and which may serve as an ongoing source of bioavailable Pu as they are subjected to weathering into the future. © 2014, Elsevier Ltd.
Plutonium uptake in wildlife at Maralinga, South Australia
(Australian Nuclear Science and Technology Organisation, 2012-10-16) Johansen, MP; Child, DP; Collins, RN; Davis, E; Doering, C; Harrison, JJ; Hotchkis, MAC; Payne, TE; Mokhber-Shahin, L; Ryan, B; Thiruvoth, S; Twining, JR; Wilsher, KL; Wood, MD
This study examined accumulation of plutonium (Pu) in wildlife at Maralinga, South Australia, where a 1950s series of experiments dispersed unfissioned Pu onto the landscape. The residual Pu concentrations that remain today are lower than the site clean-up level, but are sufficient to provide a rare opportunity to study wildlife organisms that have been exposed to a food web and soils containing elevated Pu. Analysis was by gamma- and alpha- spectroscopy, and by accelerator mass spectrometry at ANSTO. Uptake of Pu was quantified by concentration ratios, defined as average concentration in the whole-organism, to that of their host soil (CRwo-soil). The geometric mean of CRwo-soil values for all organisms was 0.002 (geometric standard deviation – 4.1E00) with mammals
Positron emission tomography and functional characterization of a complete PBR/TSPO knockout
(Springer Nature, 2014-11-19) Banati, RB; Middleton, RJ; Chan, RHY; Hatty, CR; Wai-Ying Kam, W; Quin, C; Graeber, MB; Parmar, A; Zahra, D; Callaghan, PD; Fok, S; Howell, NR; Grégoire, MC; Szabo, A; Pham, TQ; Davis, E; Liu, GJ
The evolutionarily conserved peripheral benzodiazepine receptor (PBR), or 18-kDa translocator protein (TSPO), is thought to be essential for cholesterol transport and steroidogenesis, and thus life. TSPO has been proposed as a biomarker of neuroinflammation and a new drug target in neurological diseases ranging from Alzheimer’s disease to anxiety. Here we show that global C57BL/6-Tspotm1GuWu(GuwiyangWurra)-knockout mice are viable with normal growth, lifespan, cholesterol transport, blood pregnenolone concentration, protoporphyrin IX metabolism, fertility and behaviour. However, while the activation of microglia after neuronal injury appears to be unimpaired, microglia from GuwiyangWurraTSPO knockouts produce significantly less ATP, suggesting reduced metabolic activity. Using the isoquinoline PK11195, the ligand originally used for the pharmacological and structural characterization of the PBR/TSPO, and the imidazopyridines CLINDE and PBR111, we demonstrate the utility of GuwiyangWurraTSPO knockouts to provide robust data on drug specificity and selectivity, both in vitro and in vivo, as well as the mechanism of action of putative TSPO-targeting drugs. Copyright © 2014, Springer Nature
Quantification of dopamine d2 receptor density and apparent affinity can be used to longitudinally assess transient striatal variations during adolescence using [11c]raclopride pet imaging
(John Wiley & Sons, Inc., 2017-04-11) Callaghan, PD; Sobbi, PF; Safavi-Naeini, M; Wimberley, CA; Davis, E; Zahra, D; Arthur, A; Rahardjo, GL; Perkins, G; Pascali, G; Reilhac-Laborde, A; Grégoire, MC
Background Transient increases in striatal dopamine D2 receptors occur during adolescence in rats, correlating with a developmental epoch where synaptic pruning occurs. Alteration of these processes with external stresses during adolescence may lead to affective disorders later in life. Longitudinal PET imaging with [11C]raclopride using a partial saturation design allows assessment of density (Bavail) and affinity changes (appKd) to map neurodevelopmental changes in D2 expression, which necessitates a significant level of receptors occupancy during the PET study. Aims Validate that repeated transient partial saturation of D2 receptors does not bias measures of D2 Bavail and appKd assessed using PET/CT imaging with [11C]raclopride. Methods Three cohorts of male Sprague-Dawley rats (n=6-7/group) underwent a single session of PET/CT imaging (INVEON, Siemens, USA) with [11C]raclopride (5 nmol injected i.v.) as naïve or after repeated partial saturation of D2 receptors: Cohort A received 5nmol raclopride (i.v) weekly from PND35 (postnatal day) to PND96 with PET imaging session at PND96, cohort B was scanned at PND96; Cohort C was scanned at PND35 Datasets were reconstructed (2D-FBP), coregistered with CT and time-activity data extracted using age matched atlas-based volumes of interest (striatum, cerebellum). in vivo receptor density and appKd were derived using kinetic modelling (comparisons used 1-way ANOVA follow by post hoc test). Results Expected differences in Bavail and appKd were seen between the adolescent (PND35) and the adult (PND96) cohorts, corresponding with increases in D2 receptor consistently reported in the literature using post mortem methods. No significant difference was observed in both Bavail and appKd in cohort A, exposed to repeated D2 partial saturation, compared to the naïve cohort B. Conclusion Longitudinal quantification of dopamine D2 receptor density and apparent affinity in vivo using [11C]raclopride PET imaging with partial saturation can be used to map changes in adolescent and adult rats.
Simultaneous scanning of two mice in a small-animal PET scanner: a simulation-based assessment of the signal degradation
(IOP science publishing, 2016-01-21) Reilhac, A; Boisson, F; Wimberley, CA; Parmar, A; Zahra, D; Hamze, H; Davis, E; Arthur, A; Bouillot, C; Charil, A; Grégoire, MC
In PET imaging, research groups have recently proposed different experimental set ups allowing multiple animals to be simultaneously imaged in a scanner in order to reduce the costs and increase the throughput. In those studies, the technical feasibility was demonstrated and the signal degradation caused by additional mice in the FOV characterized, however, the impact of the signal degradation on the outcome of a PET study has not yet been studied. Here we thoroughly investigated, using Monte Carlo simulated [18F]FDG and [11C]Raclopride PET studies, different experimental designs for whole-body and brain acquisitions of two mice and assessed the actual impact on the detection of biological variations as compared to a single-mouse setting. First, we extended the validation of the PET-SORTEO Monte Carlo simulation platform for the simultaneous simulation of two animals. Then, we designed [18F]FDG and [11C]Raclopride input mouse models for the simulation of realistic whole-body and brain PET studies. Simulated studies allowed us to accurately estimate the differences in detection between single- and dual-mode acquisition settings that are purely the result of having two animals in the FOV. Validation results showed that PET-SORTEO accurately reproduced the spatial resolution and noise degradations that were observed with actual dual phantom experiments. The simulated [18F]FDG whole-body study showed that the resolution loss due to the off-center positioning of the mice was the biggest contributing factor in signal degradation at the pixel level and a minimal inter-animal distance as well as the use of reconstruction methods with resolution modeling should be preferred. Dual mode acquisition did not have a major impact on ROI-based analysis except in situations where uptake values in organs from the same subject were compared. The simulated [11C]Raclopride study however showed that dual-mice imaging strongly reduced the sensitivity to variations when mice were positioned side-by-side while no sensitivity reduction was observed when they were facing each other. This is the first study showing the impact of different experimental designs for whole-body and brain acquisitions of two mice on the quality of the results using Monte Carlo simulated [18F]FDG and [11C]Raclopride PET studies. © 2016 Institute of Physics and Engineering in Medicine
Synthesis and biological characterisation of 18F-SIG343 and 18F-SIG353, novel and high selectivity σ2 radiotracers, for tumour imaging properties
(Springer Nature, 2013-12-11) Nguyen, VH; Pham, TQ; Fookes, CJR; Berghofer, PJ; Greguric, I; Arthur, A; Mattner, F; Rahardjo, GL; Davis, E; Howell, NR; Grégoire, MC; Katsifis, A; Shepherd, R
Sigma2 (σ2) receptors are highly expressed in cancer cell lines and in tumours. Two novel selective 18F-phthalimido σ2 ligands, 18F-SIG343 and 18F-SIG353, were prepared and characterised for their potential tumour imaging properties. © 2013 Nguyen et al.; licensee Springer.
Test-retest reliability and inter scanner variability of 11C-raclopride striatal binding potentials between two INVEON PET/CT imaging systems for naïve Sprague Dawley rats
(Wiley, 2014-04-16) Callaghan, PD; Zahra, D; Wimberley, CA; Arthur, A; Rahardjo, GL; Hamze, H; Davis, E; Nguyen, A; Boisson, F; Perkins, G; Pascali, G; Reilhac, A; Grégoire, MC
Background: 11C-raclopride is a routine tracer for quantification of dopamine D2 receptors in neurological and psychiatric disease. D2 imaging in key longitudinal models has significant utility of understanding mechanisms and therapeutic interventions. Aims: Optimisation of preclinical imaging and data analysis protocols for 11C-raclopride in rat brain. Methods: a) Test-retest reliability: Naïve male Sprague Dawley rats (n = 6) underwent test-retest assessment of binding potential variability, with two scans, 1 week apart. Rats were anaesthetised (1–5% isoflurane) and received 11C-raclopride (>0.1 nmol, 20–40 MBq) during 1 hour image acquisition (Siemens Inveon PET/CT), followed by a 10 minute CT scan. b) Assessment of the intersystem variability of the INVEON scanners (n = 12). Test-retest experiments were performed on a second INVEON system. c) Assessment of inter system variability with arterial blood sampling (n = 5). Acquisitions were performed (as above) with prior femoral artery cannulation: 23 blood samples (∼30 ul) were collected during PET acquisition, and plasma metabolite corrected input functions generated. PET list mode data were histogrammed (23 frames) and reconstructed with 2D filtered backprojection algorithm. The impact of some post-reconstruction image processing techniques, such iterative deconvolution of the image and data denoising techniques, onto the accuracy and reliability of the computed parameter of interest were also investigated. Binding potential parametric maps were calculated from the dynamic PET data (using either a standard reference tissue modelling using the cerebellum TAC (test-retest), and or a 2 compartment kinetic modelling with input function). Preliminary results: Significant improvements were seen for tissue activity data after denoising /iterative deconvolution (see figure). Analysis of binding potential data are currently in progress. Conclusion: Assessment of within and intersystem variability will aid the appropriate statistical design of future longitudinal 11C-raclopride imaging studies. Improvements from post-reconstruction image processing techniques show significant benefits. © 1999-2022 John Wiley & Sons, Inc.
Use of accelerator mass spectrometry (AMS) to study the migration and bioaccumulation of actinides in the environment
(Australian National University, 2014) Hotchkis, MAC; Child, DP; Payne, TE; Johansen, MP; Davis, E; Harrison, JJ; Thiruvoth, S; Wilsher, WL
The high sensitivity of AMS for actinides analysis can facilitate a range of studies aimed at improving understanding of how actinides behave in the environment. Former nuclear sites, which contain a range of levels of contamination with actinides, offer opportunities to study the migration and bioaccumulation of actinides. In addition to the evaluation of the radiological risk posed to potential human and non-human occupants of those specific sites, such studies can contribute fundamental data to the understanding of the behaviour of actinides in the environment. The Little Forest Burial Ground, located on the edge of Sydney, was used by the Australian Atomic Energy Commission to dispose of low level radioactive waste in shallow trenches in the 1960s. The waste included small amounts of uranium and plutonium with various isotopic compositions. α-spectrometry is being used as the primary method of radio-analysis in current studies of this site [1]. In addition, AMS is being applied where higher sensitivity is required, and to measure isotopes not easily measureable by α-spectrometry. 239Pu and 240Pu cannot be resolved by α-spectrometry, and 233U is poorly resolved from 234U. In both cases we can apply AMS to define these isotopic signatures. In the case of plutonium, the 240Pu/239Pu ratio can be used to distinguish local contamination sources from global fallout. The high sensitivity of AMS has enabled the detection of Pu and 233U in vegetation, providing data on uptake and bioaccumulation. The former nuclear weapons test site at Maralinga in South Australia was used in the 1950s and 1960s for seven nuclear weapon detonations and also numerous ‘safety trials’ which dispersed plutonium and uranium in the environment. By analysing plutonium in wildlife and soil samples from around this site, we are able to evaluate the uptake of plutonium and its mobility, and compare present-day results with earlier studies of the site [2]. Further work is in progress examining the distribution of plutonium in the tissues of mammals and other species inhabiting the site. By exploiting the high sensitivity of AMS, non-lethal methods for investigating actinide uptake and its effects on wildlife are being developed for this work.

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