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A micromechanical study of the viscoplasticity of voided cubic crystals is presented. The microscopic void distribution is isotropic and the macroscopic loading is hydrostatic. Three different approaches are considered. The first approach consists in idealizing the voided crystal as a hollow sphere assemblage and bounding from above the corresponding dissipation potential à la Gurson. The second approach consists in idealizing the voided crystal as a sequential laminate of infinite rank and computing the corresponding dissipation potential exactly. Finally, the third approach consists in idealizing the voided crystal as a periodic medium with a complex unit cell and computing the mechanical fields numerically via a Fast Fourier Transform (FFT) algorithm. Predictions are reported for a wide range of crystals deforming by power-law creep and rate-independent plasticity. When the plastic anisotropy is weak, a fairly good agreement between all three approaches is observed. When the plastic anisotropy is strong, by contrast, discrepancies arise. In the extreme case of plastically deficient crystals, the various predictions can exhibit different asymptotics. While estimates based on hollow-sphere assemblages predict that any deficient voided crystal is rigid under hydrostatic loading, FFT simulations and sequential laminates suggest that some deficient voided crystals with more than two linearly independent systems may dilate. Overall, estimates based on sequential laminates are found to be superior to Gurson-type estimates based on hollow sphere assemblages and to predict the hydrostatic response of cubic voided crystals with reasonable accuracy, even for relatively strong plastic anisotropies. Fil: Joëssel, Louis. Institut de Radioprotection Et de Sureté Nucléaire; Francia Fil: Vincent, Pierre Guy. Institut de Radioprotection Et de Sureté Nucléaire; Francia Fil: Garajeu, Mihail. Centre National de la Recherche Scientifique; Francia. Aix Marseille Universite; Francia Fil: Idiart, Martín Ignacio. Universidad Nacional de La Plata. Facultad de Ingeniería. Departamento de Aeronáutica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina

International audience; Localization of uranium within cells is mandatory for the comprehension of its cellular mechanism of toxicity. Secondary Ion Mass Spectrometry (SIMS) has recently shown its interest to detect and localize uranium at very low levels within the cells. This technique requires a specific sample preparation similar to the one used for Transmission Electronic Microscopy, achieved by implementing different chemical treatments to preserve as much as possible the living configuration uranium distribution into the observed sample. This study aims to compare the bioaccumulation sites of uranium within liver or kidney cells after chemical fixation and cryomethods preparations of the samples SIMS analysis of theses samples show the localization of uranium soluble forms in the cell cytoplasm and nucleus with a more homogenous distribution when using cryopreparation probably due to the diffusible portion of uranium inside the cytoplasm. © 2018 The Authors. Microscopy Research and Technique Published by Wiley Periodicals, Inc.

International audience; Living species are chronically exposed to environmental ionizing radiations from sources that can be overexpressed by nuclear accidents. In invertebrates, reproduction is the most radiosensitive studied endpoint, likely to be connected with aging. Surprisingly, aging is a sparsely investigated endpoint after chronic ionizing radiation, whereas understanding it is of fundamental interest in biology and medicine. Indeed, aging and aging-related diseases (e.g., cancer and degenerative diseases) cause about 90 % of deaths in developed countries. Therefore, glp-1 sterile Caenorhabditis elegans nematode was used to assess the impact of chronic gamma irradiation on the lifespan. Analyses were performed, at the individual level, on aging and, in order to delve deeper into the mechanisms, at the molecular level, on oxidative damage (carbonylation), biomolecules (lipids, proteins and nucleic acids) and their colocalization. We observed that ionizing radiation accelerates aging (whatever the duration (3 to 19 days)/dose (0.5 to 24 Gy)/dose rate (7 and 52 mGy.h 1) tested) leading to a longevity value equivalent to that of wt nematode (~25-30 days). Moreover, the level of protein oxidative damage (carbonylation) turned out to be good cellular biomarker of aging, since it increases with age. Conversely, chronic radiation treatments reduced carbonylation levels and induced neutral lipid catabolism whatever the dose rate and the final delivered dose. Finally, under some conditions a lipid-protein colocalization without any carbonyl was observed; this could be linked to yolk accumulation in glp-1 nematodes. To conclude, we noticed through this study a link between chronic gamma exposure, lifespan shortening and lipid level decrease associated with a decrease in the overall carbonylation.

The presence of 137Cesium (137Cs) in the environment after nuclear accidents at Chernobyl and more recently Fukushima Daiichi raises many health issues for the surrounding populations chronically exposed through the food chain. To mimic different exposure situations, we set up a male rat model of exposure by chronic ingestion of a 137Cs concentration likely to be ingested daily by residents of contaminated areas (6500 Bq.l−1) and tested contaminations lasting 9 months for adult, neonatal and fetal rats. We tested plasma and serum biochemistry to identify disturbances in general indicators (lipids, proteins, carbohydrates and electrolytes) and in biomarkers of thyroid, heart, brain, bone, kidney, liver and testis functions. Analysis of the general indicators showed increased levels of cholesterol (+26%), HDL cholesterol (+31%), phospholipids B (+15%) and phosphorus (+100%) in the postnatal group only. Thyroid, heart, brain, bone and kidney functions showed no blood changes in any model. The liver function evaluation showed changes in total bilirubin (+67%) and alkaline phosphatase (–11%) levels, but only for the rats exposed to 137Cs intake in adulthood. Large changes in 17β-estradiol (–69%) and corticosterone (+36%) levels affected steroidogenesis, but only in the adult model. This study showed that response profiles differed according to age at exposure: lipid metabolism was most radiosensitive in the postnatal model, and steroid hormone metabolism was most radiosensitive in rats exposed in adulthood. There was no evidence of deleterious effects suggesting a potential impact on fertility or procreation.

International audience; Platinum (Pt) is considered a Technology Critical Element (TCE) and an emerging metallic contaminant with increasing release into the environment. Gaps in knowledge and understanding of environmental levels, fate and effects of Pt still exist, especially in the marine environment. This work presents Pt concentrations in the northwestern Mediterranean coast including: (i) temporal variability from sediment cores and farmed mussels in the Toulon Bay (historically affected by intense human activities) and (ii) spatial distribution from recent wild mussels collected along ∼ 700 km coastline with contrasting ecosystems (including natural reserves), quantified using voltammetry and inductively coupled plasma-mass spectrometry. The historical (>100 years) record of Pt in sediments from the Toulon Bay suggests the existence of non-negligible Pt sources older than those related to vehicle emission devices, such as petrol industry and coal-fired activities. A strong Pt increase in more recent sediments (from ∼12 to 16 ng g−1) and mussels (8-fold increase from ∼0.12 to 0.80 ng g−1) covering the past 25 years reflect the overall evolution of Pt demand in Europe (∼20-fold increase for vehicle catalysts in 20 years). Spatial biomonitoring of Pt in mussels along the northwestern Mediterranean coast is assumed to reflect inter-site differences of Pt exposure (0.09–0.66 ng g−1) despite seasonal effect on tissue development. This study highlights the need for thorough and regular monitoring of Pt levels in sediments and biota from urbanized coastal areas in order to better assess the environmental impact of this TCE, including potential risks for marine organisms. © 2018

International audience; The present study reports the evidence of a radioactive contamination in a wetland located downstream from a former French U mine in Brittany. This situation is demonstrated according to the measurements of gamma dose rates and activity ratios of 238U and 232Th-decay series nuclides, which give the justification regarding the accumulation of significant amounts of 238U, 230Th and 226Ra in this wetland. The dose rate map highlights an increase of radiation level along the former mine water pathway compared to the background value, with a maximum value of 1500 nSv.h−1 reached in the wetland. Activities of 238U, 230Th and 226Ra and 232Th/238U ratios measured in surface wetland soils are significantly higher than the geochemical background. 230Th/238U ratios less than unity suggest a preferential accumulation of U in the wetland, compared to its daughter isotopes. Moreover, the loss of 226Ra compared to 230Th raises its higher mobility compared to its parent isotope. In far-field sediments, 226Ra/238U ratio of 1.76 implies a different geochemical behavior of U, which could be explained by the occurrence of mobile U species. The results suggest that contamination of wetland soils and far-field sediments could result from discharges of underground mine waters. © 2018 Elsevier Ltd

International audience; Species are chronically exposed to ionizing radiation, a natural phenomenon which can be enhanced by human activities. The induced toxicity mechanisms still remain unclear and seem depending on the mode of exposure, i.e. acute and chronic. To better understand these phenomena, studies need to be conducted both at the subcellular and individual levels. Proteins, functional molecules in organisms, are the targets of oxidative damage (especially via their carbonylation (PC)) and are likely to be relevant biomarkers. After exposure of Caenorhabditis elegans to either chronic or acute γ rays we showed that hatching success is impacted after acute but not after chronic irradiation. At the molecular level, the carbonylated protein level in relation with dose was slightly different between acute and chronic exposure whereas the proteolytic activity is drastically modified. Indeed, whereas the 20S proteasome activity is inhibited by acute irradiation from 0.5 Gy, it is activated after chronic irradiation from 1 Gy. As expected, the 20S proteasome activity is mainly modified by irradiation whereas the 26S and 30S activity are less changed. This study provides preliminaries clues to understand the role of protein oxidation and proteolytic activity in the radiation-induced molecular mechanisms after chronic versus acute irradiation in C. elegans.

International audience; Tritium (3H) is a radioactive isotope of hydrogen. In the environment, the most common form of tritium is tritiated water (HTO). The present study aimed to identify early biomarkers of HTO contamination through the use of an aquatic model, the zebrafish (Danio rerio). We used the zebrafish embryo-larvae model to investigate the modes of action of HTO exposure at dose rates of 0.4 and 4 mGy/h, dose rates expected to induce deleterious effects on fish. Zebrafish were exposed to HTO from 3 hpf (hours post fertilization) to 96 hpf. The transcriptomic effects were investigated 24 h and 96 h after the beginning of the contamination, using mRNAseq. Results suggested an impact of HTO contamination, regardless of the dose rate, on genes involved in muscle contraction (tnnt2d, tnni2a.4, slc6a1a or atp2a1l) and eye opacity (crygm2d9, crygmxl1, mipb or lim2.3) after 24 h of contamination. Interestingly, an opposite differential expression was highlighted in genes playing a role in muscle contraction and eye opacity in 24 hpf embryos when comparing dose rates, suggesting an onset of DNA protective mechanisms. The expression of h2afx and ddb2 involved in DNA repair was enhanced in response to HTO exposure. The entrainment of circadian clock and the response to H2O2 signalling pathways were enriched at 96 hpf at 0.4 mGy/h and in both stages after 4 mGy/h. Genes involved in ROS scavenging were differentially expressed only after 24 h of exposure for the lowest dose rate, suggesting the onset of early protective mechanisms against oxidative stress. Effects highlighted on muscle at the molecular scale were confirmed at a higher biological scale, as electron microscopy observations revealed sarcomere impairments in 96 hpf larvae for both dose rates. Together with other studies, the present work provides useful data to better understand modes of action of tritium on zebrafish embryos-larvae. © 2018 Elsevier B.V.

International audience; Objective To investigate childhood cardiac arrhythmia and chronic exposure to caesium-137 (137 Cs) resulting from the Chernobyl accident.Design Prospective cross-sectional study using exposed/unexposed design conducted in the Bryansk region from May 2009 to May 2013 on children selected on the basis of 137 Cs soil deposition Control territories ([ 137 Cs]555 kBq per square metre, where children were considered as exposed). Setting Russian territories affected by the Chernobyl fallout (Bryansk region). Participants This cross-sectional study included 18 152 children aged 2-18 years and living in the Bryansk region (Russia). Main outcome measures All children received three medical examinations (ECG, echocardiography and 137 Cs whole-body activity measurement) and some of them were given with a 24-hour Holter monitoring and blood tests.Results Cardiac arrhythmia was diagnosed in 1172 children living in contaminated territories and 1354 children living in control territories. The crude prevalence estimated to 13.3% in contaminated territories was significantly lower than in control territories with 15.2% over the period 2009-2013 (P

International audience; In the general context of validation of tools useful for the characterization of ecological risk linked to ionizing radiation, the effects of an external gamma irradiation were studied in zebrafish larvae irradiated for 96 h with two dose rates 0.8 mGy/d, which is close to the level recommended to protect ecosystems from adverse effects of ionizing radiation (0.24 mGy/d) and a higher dose rate of 570. mGy/d. Several endpoints were investigated, such as mortality, hatching, and some parameters of embryo-larval development, immunotoxicity, apoptosis, genotoxicity, neurotoxicity and histological alterations. Results showed that an exposure to gamma rays induced an acceleration of hatching for both doses and a decrease of yolk bag diameter for the highest dose, which could indicate an increase of global metabolism. AChE activity decreased with the low dose rate of gamma irradiation and alterations were also shown in muscles of irradiated larvae. These results suggest that gamma irradiation can induce damages on larval neurotransmission, which could have repercussions on locomotion. DNA damages, basal ROS production and apoptosis were also induced by irradiation, while ROS stimulation index and EROD biotransformation activity were decreased and gene expression of acetylcholinesterase, choline acetyltransferase, cytochrome p450 and myeloperoxidase increased. These results showed that ionizing radiation induced an oxidative stress conducting to DNA damages. This study characterized further the modes of action of ionizing radiation in fish. © 2015 Elsevier B.V.

International audience; Fog water deposition can represent an important part of the atmospheric water, nutrient and pollutant inputs in specific areas such as mountainous or coastal regions (Shimadera et al., 2011). In order to determine the potential of fog water deposition on plants, a field experiment has been performed in the northeast of France to determine fog droplet deposition velocity on different types of plants. The main objective is to improve deposition models by enabling them to accurately account for water inputs from fog or low clouds at ground level. The flux of deposited fog water was estimated by exposing plants to fog and weighing them with a precision balance. Contrary to other flux measurement methods, the weighing method is simple to set up. Three plant types (small conifers, grass and cabbages) plus bare soil were used as impaction and deposition surfaces. A Particulate Volume Monitor (PVM-100) provided the liquid water content (LWC) to calculate fog droplet deposition velocities, and a Fog Monitor (FM-120), the characterization of the droplet size distribution. Two fog events with different features (visibility, LWC and droplet number) were compared with regard to deposition velocity. When wind speed was below 4 m s–1, mean fog droplet deposition velocities ranged from less than 2.2 cm s–1 on bare soil to 40 cm s–1 on cypress. Thus, the impaction of fog droplets can be an important part of fog water deposition on plants. © Taiwan Association for Aerosol Research.

International audience; H Miloudi, M Locatelli, G Autret, D Balvay, A Desbrée, E Blanchardon, J M Bertho application of RODES software to experimental biokinetic data for dose assessment in mice and rats. In support of experimental studies of chronic, long-term contamination in rodents, voxel-based computer models were built representing adult mice and juvenile, adult and elderly rats of both sexes. RODES software was created to calculate absorbed radiation doses to organs with these specific anatomical models. Absorbed doses were then calculated starting from previously published biokinetic data. Whole body doses showed less than 5% differences between calculation with RODES and calculation with the ICRP Publication 108 model for long term exposure to 90Sr of mice. Similar results were obtained for long term exposure to 137Cs. Dose distribution for 90Sr internal contamination also showed that the dose to the skeleton is six fold more as compared to the whole body dose while radiation dose to other organs is less than the mean whole body dose. These results underline the importance of using specific anatomical models according to the age and the sex of experimental animals. © 2017 IOP Publishing Ltd.

International audience; The French Institute for Radiation Protection and Nuclear Safety (IRSN), with the support of the Ministry of Environment, compiled a database (BDFA) to define and characterize known potentially active faults of metropolitan France. The general structure of BDFA is presented in this paper. BDFA reports to date 136 faults and represents a first step toward the implementation of seismic source models that would be used for both deterministic and probabilistic seismic hazard calculations. A robustness index was introduced, highlighting that less than 15ĝ€% of the database is controlled by reasonably complete data sets. An example of transposing BDFA into a fault source model for PSHA (probabilistic seismic hazard analysis) calculation is presented for the Upper Rhine Graben (eastern France) and exploited in the companion paper (Chartier et al., 2017, hereafter Part 2) in order to illustrate ongoing challenges for probabilistic fault-based seismic hazard calculations. © Author(s) 2017.

International audience; This study investigated the accumulation pattern and biological effects (genotoxicity and histopathology) to adult zebrafish (male and female) exposed to a nominal waterborne concentration of 20 μg L−1 of depleted uranium (DU) for 28 days followed by 27 days of depuration. Accumulation pattern showed that (i) DU accumulated in brain, (ii) levels in digestive tract were higher than those measured in gills and (iii) levels remained high in kidney, brain and ovary despite the 27 days of depuration period. Genotoxicity, assessed by comet assay, was significant not only during DU exposure, but also during depuration phase. Gonads, in particular the testes, were more sensitive than gills. The histology of gonads indicated severe biological damages in males. This study improved knowledge of ecotoxic profile of uranium, for which a large range of biological effects has already been demonstrated. © 2018 Elsevier B.V.

International audience; The aim of this paper is to report new experimental results on the effect of turbulence on the propagation speed of hydrogen/air flames. To do so, a new experimental setup, called the spherical bomb, has been designed and built at CNRS-ICARE laboratory. With this new setup, the effect of a given and well-characterized turbulence intensity on the increase of hydrogen/air flame speed can be investigated. This new facility consists of a spherical vessel equipped (563 mm internal diameter) equipped with 8 motors which are linked to fans inside the bomb. Fan actuation induces the generation of a turbulent flow inside the vessel prior to any ignition. The spherical bomb is equipped with 4 quartz windows (200 mm optical diameter) that allow the use of a Particle Image Velocimetry diagnostic in order to characterize the turbulence level inside the bomb. The flame propagation was recorded using a high speed camera at 19,002 frames per second. These experiments were performed for lean to stoichiometric hydrogen/air mixtures (16–20% of H2 in air), initially at ambient temperature and pressure, and for a rotation speed from 1000 to 5000 rpm. The PIV measurements showed that a homogeneous and isotropic turbulence is created with a fluctuation speed that can reach 4 m/s at 5000 rpm. © 2016 Elsevier B.V.

International audience; The aim of the present study is to analyse by microarray techniques how gene expression is modulated after exposure to low and very low doses of ionizing radiation, to evaluate if the pattern of gene expression shows dose dependence, and to search for putative regulatory mechanisms behind the observed gene-expression modifications. For this, whole blood samples from five healthy donors were exposed in six doses between 5 and 500mGy. Total RNA extraction from CD4+ lymphocytes was done at four different post-irradiation times. After mRNA amplification, aRNAs were hybridized on DNA microarrays. The results indicated that up-regulation was twice than down-regulation. Surprisingly, the number of modulated genes does not seem to change drastically with dose, even at the lowest dose of 5. mGy. Clustering analysis revealed seven gene expression clusters with different dose dependence profiles. The functional analysis showed that the genes which increased their expression with the dose were related to p53 pathway and DNA damage response. This could be observed from 25. mGy, but became very clear at doses equal or greater than 100. mGy. On the other hand, genes with a constant modulation of their expression in all the tested doses were related to cellular respiration, ATP metabolic process and chromatin organization. These latter molecular mechanisms seem to be triggered at very low doses (5-25. mGy). In silico promoter analysis seems to confirm the implication of transcription factors related to the pathways mentioned above. © 2013 Elsevier B.V.

The work described is concerned with the way micron-size particles attached to a surface are resuspended when exposed to a turbulent flow. An improved version of the Rock'n'Roll model (Reeks and Hall, 2001) is developed where this model employs a stochastic approach to resuspension involving the rocking and rolling of a particle about surface asperities arising from the moments of the fluctuating drag forces acting on the particle close to the surface. In this work, the model is improved by using values of both the streamwise fluid velocity andacceleration close to the wall obtained from Direct Numerical Simulation (DNS) of turbulentchannel flow. Using analysis and numerical calculations of the drag force on a sphere near a wall in shear flow (O'Neill (1968) and Lee and Balachandar (2010)) these values are used to obtain the joint distribution of the moments of the fluctuating drag force and its time derivative acting on a particle attached to a surface. In so doing the influence of highly non-Gaussian forces (associated with the sweeping and ejection events in a turbulent boundary layer) on short and long term resuspension rates is examined for a sparse monolayer coverage of particles, along with the dependence of the resuspension upon the timescale of the particle motion attached to the surface, the ratio of the rms/ mean of the removal force and the distribution of adhesive forces. Model predictions of the fraction resuspended are compared with experimental results., 31 pages 21 figures

International audience; In diagnostic nuclear medicine, mean absorbed doses to patients' organs and effective doses are published for standard stylised anatomic models. To provide more realistic and detailed geometries of the human morphology, the International Commission on Radiological Protection (ICRP) has recently adopted male and female voxel phantoms to represent the reference adult. This work investigates the impact of the use of these new computational phantoms. The absorbed doses were calculated for 11 different radiopharmaceuticals currently used in diagnostic nuclear medicine. They were calculated for the ICRP 110 reference computational phantoms using the OEDIPE software and the MCNP extended Monte Carlo code. The biokinetic models were issued from ICRP Publications 53, 80 and 106. The results were then compared with published values given in these ICRP Publications. To discriminate the effect of anatomical differences on organ doses from the effect of the calculation method, the Monte Carlo calculations were repeated for the reference adult stylised phantom. The voxel effect, the influence of the use of different densities and nuclear decay data were also investigated. Effective doses were determined for the ICRP 110 adult reference computational phantom with the tissue weighting factor of ICRP Publication 60 and the tissue weighting factors of ICRP Publication 103. The calculation method and, in particular, the simulation of the electron transport have a significant influence on the calculated doses, especially, for small and walled organs. Overestimates of >200 % were observed for the urinary bladder wall of the stylised phantom compared with the computational phantoms. The unrealistic organ topology of the stylised phantom leads to important dose differences, sometimes by an order of magnitude. The effective doses calculated using the new computational phantoms and the new tissue weighting factors are globally lower than the published ones, except for some radiopharmaceuticals, where the differences can reach 60 % higher than the published values. This study analyses the first set of absorbed and effective doses with the new ICRP male and female reference computational phantoms for different radiopharmaceuticals. It highlights the importance of taking into account the electron transport and the realism of the shape and inter-organ distances of the anthropomorphic model used. © The Author 2013. Published by Oxford University Press. All rights reserved.

International audience; Consequences of uranium contamination have been extensively studied in brain as cognitive function impairments were observed in rodents. Locomotor disturbances have also been described in contaminated animals. Epidemiological studies have revealed increased risk of motor neuron diseases in veterans potentially exposed to uranium during their military duties. To our knowledge, biological response of spinal cord to uranium contamination has not been studied even though it has a crucial role in locomotion. Four groups of rats were contaminated with increasing concentrations of uranium in their drinking water compared to a control group to study cellular mechanisms involved in locomotor disorders. Nissl staining of spinal cord sections revealed the presence of chromatolytic neurons in the ventral horn. This observation was correlated with a decreased number of motor neurons in the highly contaminated group and a decrease of SMN1 protein expression (Survival of Motor Neuron 1). While contamination impairs motor neuron integrity, an increasing number of microglial cells indicates the trigger of a neuroinflammation process. Potential overexpression of a microglial recruitment chemokine, MCP-1 (Monocyte Chimioattractant Protein 1), by motor neurons themselves could mediate this process. Studies on spinal cord appear to be relevant for risk assessment of population exposed via contaminated food and water. © 2016 Elsevier Ireland Ltd.

Corrigendum to “Three-dimensional motion of particles in a shear flow near a rough wall” (Three-dimensional motion of particles in a shear flow near a rough wall (2016) 96 (69–95), (S0021850215001664), (10.1016/j.jaerosci.2015.10.004)); International audience; A model is proposed for the three-dimensional motion of a small spherical particle entrained by the shear flow of a gas near a rough wall. On the basis of experimental results, the wall is modeled by an average small roughness and some much larger isolated peaks, which are yet smaller than the sphere radius. When encountering a high peak of roughness, the particle may be lifted if the aerodynamic force and torque take over the force and torque due to adhesion on the wall. The aerodynamics is treated using previous analytical results for the creeping flow around a particle near a wall. Values of the adhesion forces of a particle near a rough wall are obtained experimentally. When lifted from the wall, the particle follows a three-dimensional trajectory while rotating around the peak of roughness. Examples of calculated trajectories show that the particle may or may not reach the top of the peak, depending on the various physical parameters. Since the velocity of the particle when leaving the peak grows with its final distance from the wall, that velocity is essential for the subsequent particle resuspension by the ambient shear flow. © 2015 Elsevier Ltd.

International audience; Field experiments and laboratory studies were performed to investigate migration processes of plutonium isotopes from a near-surface radioactive waste trench to the underlying sandy aquifer at the Red Forest waste dump in the Chernobyl zone. The objectives of these experiments were to characterize the spatial distribution and possible migration mechanisms of plutonium in the aquifer. During 2002-2007 experimental investigations were carried out and spatial distributions of plutonium isotopes ( 239,240Pu, 238Pu), 90Sr and major ions in the aquifer in the direction of the groundwater flow were obtained. Specific activities of radionuclides in groundwater depended on the location of the piezometer and varied in the range of 1-360mBqkg -1 for 239,240Pu, 0.5-180mBqkg -1 for 238Pu and n-n·10 4 Bqkg -1 for 90Sr. It was found that the spatial features of the distributions of plutonium and strontium specific activities in the upper eolian aquifer were similar, i.e. there was a correlation between the positions of the activity maxima of the radionuclides. The Pu isotopes plume in the aquifer spreads about 15m downstream of the radionuclides source. Characterization of the initial radionuclide composition of the waste showed that all plutonium in the aquifer originated from the trench. The ratio of plutonium isotopes ( 239,240Pu/ 238Pu) at the sampling time was the same in waste material and in groundwater samples. In situ ultrafiltration of several groundwater samples was carried out. The size fractionation data obtained suggest that a significant part of plutonium (50-98%) in the groundwater sampled close to the source from the upper part of the aquifer is associated with a very low molecular weight fraction (andlt;1kDa). © 2012 Elsevier Ltd.

International audience; Depleted uranium (DU) is uranium with a lower content of the fissile isotope U-235 than natural uranium. It is a radioelement and a waste product from the enrichment process of natural uranium. Because of its very high density, it is used in the civil industry and for military purposes. DU exposure can affect many vital systems in the human body, because in addition to being weakly radioactive, uranium is a toxic metal. It should be emphasized that, to be exposed to radiation from DU, you have to eat, drink, or breathe it, or get it on your skin. This particular study is focusing on the health effects of DU for the cholesterol metabolism. Previous studies on the same issue have shown that the cholesterol metabolism was modulated at molecular level in the liver of laboratory rodents contaminated for nine months with DU. However, this modulation was not correlated with some effects at organs or body levels. It was therefore decided to use a "pathological model" such as hypercholesterolemic apolipoprotein E-deficient laboratory mice in order to try to clarify the situation. The purpose of the present study is to assess the effects of a chronic ingestion (during 3 months) of a low level DU-supplemented water (20 mg L -1) on the above mentioned mice in order to determine a possible contamination effect. Afterwards the cholesterol metabolism was studied in the liver especially focused on the gene expressions of cholesterol-catabolising enzymes (CYP7A1, CYP27A1 and CYP7B1), as well as those of associated nuclear receptors (LXRα, FXR, PPARα, and SREBP 2). In addition, mRNA levels of other enzymes of interest were measured (ACAT 2, as well as HMGCoA Reductase and HMGCoA Synthase). The gene expression study was completed with SRB1 and LDLr, apolipoproteins A1 and B and membrane transporters ABC A1, ABC G5. The major effect induced by a low level of DU contamination in apo-E deficient mice was a decrease in hepatic gene expression of the enzyme CYP7B1 (-23%) and nuclear receptors LXRα (-24%), RXR (-32%), HNF4α (-21%) when compared to unexposed ones. These modifications on cholesterol metabolism did not lead to increased disturbances that are specific for apolipoprotein E-deficient mice, suggesting that chronic DU exposure did not worsen the pathology in this experimental model. In conclusion, the results of this study indicate that even for a sensitive pathologic model the exposure to a low dose of DU has no relevant impact. The results confirm the results of our first study carried out on healthy laboratory rodents where a sub-chronic contamination with low dose DU did not affect in vivo the metabolism of cholesterol.

International audience; This study aimed to compare the cell stress effects of low and high uranium concentrations and relate them to its localization, precipitate formation, and exposure time. The time-course analysis shows that uranium appears in cell nuclei as a soluble form within 5 min of exposure, and quickly induces expression of antioxidant and DNA repair genes. On the other hand, precipitate formations began at the very beginning of exposure at the 300-μM concentration, but took longer to appear at lower concentrations. Adaptive response might occur at low concentrations but are overwhelmed at high concentrations, especially when uranium precipitates are abundant. © 2015 Elsevier B.V.

International audience; This study combines in situ gamma spectrometry performed at different scales, in order to accurately locate the contamination pools, to identify the concerned radionuclides and to determine the distribution of the contaminants from soil to bearing phase scale. The potential mobility of several radionuclides is also evaluated using sequential extraction. Using this procedure, an accumulation area located downstream of a former French uranium mine and concentrating a significant fraction of radioactivity is highlighted. We report disequilibria in the U-decay chains, which are likely related to the processes implemented on the mining area. Coupling of mineralogical analyzes with sequential extraction allow us to highlight the presence of barium sulfate, which may be the carrier of the Ra-226 activities found in the residual phase (Ba(Ra)SO4). In contrast, uranium is essentially in the reducible fraction and potentially trapped in clay-iron coatings located on the surface of minerals. © 2015 Elsevier Ltd.

International audience; Airborne activity levels of uranium and thorium series were measured in the vicinity (1.1km) of auranium (UF4) processing plant, located in Malvési, south of France. Regarding its impact on the environment, this facility is characterized by its routine atmospheric releases of uranium and by the emission of radionuclide-labelled particles from a storage pond filled with waste water or that contain dried sludge characterized by traces of plutonium and thorium (230Th). This study was performed during a whole year (November 2009-November 2010) and based on weekly aerosol sampling. Thanks to ICP-MS results, it was possible to perform investigations of uranium and thorium decay product concentration in the air. The number of aerosol filters sampled (50) was sufficient to establish a relationship between airborne radionuclide variations and the wind conditions. As expected, the more the time spent in the plume, the higher the ambient levels. The respective contributions of atmospheric releases and resuspension from local soil and waste ponds on ambient dust load and uranium-bearing aerosols were estimated. Two shutdown periods dedicated to facility servicing made it possible to estimate the resuspension contribution and to specify its origin (local or regional) according to the wind direction and remote background concentration. Airborne uranium mainly comes from the emission stack and, to a minor extent (~20%), from wind resuspension of soil particles from the surrounding fields and areas devoted to waste storage. Moreover, weighed activity levels were clearly higher during operational periods than for shutdown periods. © 2014 Elsevier Ltd.

International audience; In radioecology, the need to understand the long-term ecological effects of radioactive contamination has been emphasised. This requires that the health of field populations is evaluated and linked to an accurate estimate of received radiological dose. The aim of the present study was to assess the effects of current radioactive contamination on nematode assemblages at sites affected by the fallout from the Chernobyl accident. First, we estimated the total dose rates (TDRs) absorbed by nematodes, from measured current soil activity concentrations, Dose Conversion Coefficients (DCCs, calculated using EDEN software) and soil-to-biota concentration ratios (from the ERICA tool database). The impact of current TDRs on nematode assemblages was then evaluated. Nematodes were collected in spring 2011 from 18 forest sites in the Chernobyl Exclusion Zone (CEZ) with external gamma dose rates, measured using radiophotoluminescent dosimeters, varying from 0.2 to 22μGyh-1. These values were one order of magnitude below the TDRs. A majority of bacterial-, plant-, and fungal-feeding nematodes and very few of the disturbance sensitive families were identified. No statistically significant association was observed between TDR values and nematode total abundance or the Shannon diversity index (H'). The Nematode Channel Ratio (which defines the relative abundance of bacterial- versus fungal-feeding nematodes) decreased significantly with increasing TDR, suggesting that radioactive contamination may influence nematode assemblages either directly or indirectly by modifying their food resources. A greater Maturity Index (MI), usually characterising better soil quality, was associated with higher pH and TDR values. These results suggest that in the CEZ, nematode assemblages from the forest sites were slightly impacted by chronic exposure at a predicted TDR of 200μGyh-1. This may be imputable to a dominant proportion of pollutant resistant nematodes in all sites. This might result from a selection at the expense of sensitive species after the accident. © 2013 Elsevier B.V.

International audience; Uranium (U) accumulates and produces its toxic effects preferentially in the kidneys, especially in the proximal tubular structure. U disturbs the balance of pro-/antioxidants in the renal cortex after acute exposure. Other nephrotoxic agents, such as medications, also cause oxidative stress, but the effects of coexposure are not known. The aim of this study was to analyze the effect of chronic exposure to U and acute gentamicin treatment on the pro- and antioxidant status of the renal cortex of rats. Animals were chronically exposed (9 months) to a nonnephrotoxic level of U (40 mg/L) and then treated with daily injections of gentamicin at a range of doses (0, 5, 25, 100, and 150 mg/kg) during the last week of contamination. We studied changes in the gene expression, protein expression, and enzyme activity of key factors involved in the pro-/antioxidant balance in the renal cortex. At and above a dose of 100 mg/kg, gentamicin decreased the messenger RNA (mRNA) levels of catalase (CAT), copper/zinc superoxide dismutase (SOD) and increased the mRNA levels of heme oxygenase-1 in contaminated rats. This treatment decreased CAT activity, but did not significantly change the SOD protein level. Chronic exposure to U did not worsen these effects in our experimental conditions. In conclusion, gentamicin treatment disturbed the oxidative balance in our model's renal cortex, but the chronic exposure to U at this nonnephrotoxic level did not appear to reinforce these effects. © The Author(s) 2013.

International audience; Radiation dose to the eye lens is a crucial issue for interventional cardiologists (ICs) who are exposed during the procedures they perform. This paper presents a retrospective assessment of the cumulative eye lens doses of ICs enrolled in the O'CLOC study for Occupational Cataracts and Lens Opacities in interventional Cardiology. Information on the workload in the catheterisation laboratory, radiation protection equipment, eye lens dose per procedure and dose reduction factors associated with eye-protective equipment were considered. For the 129 ICs at an average age of 51 who had worked for an average period of 22 years, the estimated cumulative eye lens dose ranged from 25 mSv to more than 1600 mSv; the mean+SD was 423+359 mSv. After several years of practice, without eye protection, ICs may exceed the new ICRP lifetime eye dose threshold of 500 mSv and be at high risk of developing early radiation-induced cataracts. Radiation protection equipment can reduce these doses and should be used routinely. © The Author 2012. Published by Oxford University Press. All rights reserved.

International audience; Alzheimer's disease is associated with genetic risk factors, of which the apolipoprotein E (ApoE) is the most prevalent, and is affected by environmental factors that include education early in life and exposure to metals. The industrial and military use of depleted uranium (DU) resulted in an increase of its deposition in some areas and led to a possible environmental factor. The present study aims to ascertain the effects on the behaviour and the metabolism of cholesterol and acetylcholine of ApoE-/- mice exposed to enriched environment (EE) and exposed to DU (20 mg/L) for 14 weeks. Here we show that ApoE-/- mice were unaffected by the EE and their learning and memory were similar to those of the non-enriched ApoE-/- mice. ApoE-/- mice showed a significant decrease in total (-16 %) and free (-16 %) cholesterol in the entorhinal cortex in comparison to control wild-type mice. Whatever the housing conditions, the exposure to DU of ApoE-/- mice impaired working memory, but had no effect on anxiety-like behaviour, in comparison to control ApoE-/- mice. The exposure of ApoE-/- mice to DU also induced a trend toward higher total cholesterol content in the cerebral cortex (+15 %) compared to control ApoE-/- mice. In conclusion, these results demonstrate that enriched environment does not ameliorate neurobehaviour in ApoE-/- mice and that ApoE mutation induced specific effects on the brain cholesterol. These findings also suggested that DU exposure could modify the pathology in this ApoE model, with no influence of housing conditions. © 2013 Springer Science+Business Media.

International audience; Several countries have increased efforts to develop medical countermeasures to protect against radiation toxicity due to acts of bioterrorism as well as cancer treatment. Both acute radiation injuries and delayed effects such as cutaneous effects and impaired wound repair depend, to some extent, on angiogenesis deficiency. Vascular damage influences levels of nutrients, oxygen available to skin tissue and epithelial cell viability. Consequently, the evolution of radiation lesions often becomes uncontrolled and surgery is the final option-amputation leading to a disability. Therefore, the development of strategies designed to promote healing of radiation injuries is a major therapeutic challenge. Adult mesenchymal stem cell therapy has been combined with surgery in some cases and not in others and successfully applied in patients with accidental radiation injuries. Although research in the field of radiation skin injury management has made substantial progress in the past 10 y, several strategies are still needed in order to enhance the beneficial effect of stem cell therapy and to counteract the deleterious effect of an irradiated tissue environment. This review summarises the current and evolving advances concerning basic and translational research based on stem cell therapy for the management of radiological burns. © World Health Organization 2012. All rights reserved.

International audience; Background Bone is the main site of uranium accumulation after long term contamination. Several studies describe that at high dose of exposure, uranium impairs bone growth. Nevertheless little is known about the effects of chronic exposure at low doses of this radionuclide on bone, especially when ingested via drinking water, which is considered as the main exposure pathway for the public. Methods In this study, male rats were exposed to natural uranium in drinking water for a 9 month period, either at 40 mg l- 1 starting just after birth (post-natal model) or starting at 3 months of age (adult model). Results In the post-natal model at 40 mg l- 1, three-dimensional microtomography analysis showed that NU decreased significantly the cortical bone diameter in NU-contaminated rats. Bone histomorphometry analysis also showed a significant increase of the osteoid thickness in trabecular bone of the femur of NU-contaminated rats. In addition, mRNA expression in trabecular bone of genes involved in osteoblast differentiation (OSX, BMP2, RUNX2), bone remodeling (TRAP, OCN), bone mineralization (BSP, OPN, DMP1), calcium transport (TRPV5) as well as vitamin D receptor (VDR) was significantly decreased in this model. In contrast, in the adult model, no morphometric, cellular and molecular changes were observed in bone. General significance This study showed for the first time that NU at this concentration has no detectable effect in adult bone while it significantly affects growing bone, which thus appears more sensitive to low dose contamination by this radionuclide. © 2012 Elsevier B.V. All rights reserved.

Potential internal contamination of workers is monitored by periodic bioassay measurements interpreted in terms of intake and committed effective dose by the use of biokinetic and dosimetric models. After a prospective evaluation of exposure at a workplace, a suitable monitoring programme can be defined by choosing adequate measurement techniques and frequency. In this study, the sensitivity of a programme is evaluated by the minimum intake and dose, which may be detected with a given level of confidence by taking into account uncertainties on exposure conditions and measurements. This is made for programme optimisation, which is performed by comparing the sensitivities of different alternative programmes. These methods were applied at the AREVA NC reprocessing plant and support the current monitoring programme as the best compromise between the cost of the measurements and the sensitivity of the programme. © The Author 2010. Published by Oxford University Press. All rights reserved.

The atmospheric concentrations of 137 Cs, 210 Pb, and 7 Be were measured over a three-year period at two research stations located less than 12 km apart and at different altitudes (puy de Dome, 1465 m a.s.l. and Opme, 660 m a.s.l., France). Seasonal trends in all radionuclides were observed at both stations, with high concentration measured during the summer and low concentrations during the winter. The 210 Pb concentrations at both stations were similar to each other. Higher concentrations of both 7 Be and 137 Cs were measured at puy de Dome than at Opme. These observations can be explained by the stratospheric and upper tropospheric sources of 7 Be and the long-range transportation of 137 Cs at high altitudes. Air mass origins during sampling periods were classified into several groups by their route to the stations (marine, marine modified, continental and mediterranean). We observed that 7 Be concentrations were constant regardless of the air mass origins, unlike 137 Cs and 210 Pb concentrations that increased when influenced by continental air masses. Higher 7 Be concentrations were observed when air masses were arriving from the upper troposphere than from the boundary layer, the opposite was observed for 137 Cs. The temporal trend in concentrations of 7 Be shows good agreement with previous modelling studies suggesting that there is a good understanding of its sources and the atmospheric vertical mixing of this radionuclide. The sources and mixing of 210 Pb, however, seem to be more complex than it appeared to be in previous modelling studies.

On July 7, 2008, a leak of effluent from an Installation of Cleansing and Uranium Recovery (Tricastin, France) led to the spillage of uranium in a stream. The acute toxicity of the effluent was evaluated, and compared to the toxicity of uranium nitrate in bioassays using several organisms: Chlamydomonas reinhardtii, Daphnia magna, Chironomus riparius and Danio rerio. A sediment bioassay was also performed on C. riparius using water and sediment sampled along the river. Results showed that effluent EC50 72 h was 0.65 mg U/l for algae and LC50 48 h was 1.67 mg U/l for daphnia, while values obtained for uranium nitrate were higher. The LC50 96 h of effluent to C. riparius was 22.7 mg U/l, similar to value for uranium nitrate; the sediment collected was not toxic to C. riparius larvae. The LOEC of effluent and uranium nitrate on HT50 of D. rerio were similar (0.03 mg U/l), but larvae were more sensitive to uranium nitrate than to effluent. Our results suggest that other substances contained in the effluent could potentially be toxic to wildlife in association with uranium. In parallel, the modelling of the transfers based on uranium measurements in the surface water was used to fill data gaps and assess the impact along the river. These results provided an estimate of exposure conditions that occurred along the river. This approach allowed us to see that the risk to ecosystem during this incident was certainly low and concerned a short period of time, but it could have existed at least for some species. © 2010 Springer Science+Business Media, LLC.