[en] Uranium, thorium and their decay products are present in trace amounts in all rocks on Earth. Weathering, Mechanisms of soil formation and soil-plant transfers lead to the presence of these radionuclides in all the components of the environment and, through the food-chain transfers, they are also present in animals and men. The objective of this study consists in improving the knowledge on the levels and the variability of the activities of these radionuclides in various foodstuffs and on their sources and transfers. This study is based on the geological variability of the studied sites (granitic, volcanic and alluvial areas) where various foodstuffs are sampled (vegetables, cereals, meat, eggs and dairy products). The possible sources of radionuclides (irrigation waters and soils for plants; water, food and soils for animals) are also sampled in order to study their contribution to the measured activities in the foodstuffs. The results obtained present high variability of the activities in plants, less pronounced in animal products. For plants, the main radionuclide source seems to be the crop soils. Irrigation water, soil particle resuspension and their adhesion to plant surface seems to be important in some cases. For the activities in animal products, a significant contribution of the soil to thorium activity was highlighted. Water contribution to uranium activity in meat and eggs is an area worth further researches. Thus, this study of the possible sources of radionuclides highlights the importance of their role in the understanding of the radionuclide transfers to foodstuffs. (author)

[en] Thesis presentations have been organised in sessions which respectively addressed issues related to radiation safety, and to environment and health (urban atmosphere, dry deposition of aerosols, therapeutic benefit of an injection of mesenchymal stem cells, colorectal lesions, role of toll-like receptors (or TLR) in immune orientations induced by an abdominal irradiation. Plenary sessions also addressed these issues. Then sessions addressed issues related to parallel effects in low doses, to the parallel modelling of materials, to containment and aerosols, to neutron spectrometry and dosimetry. Some parallel sessions addressed issues related to geosphere, to severe accidents and fires. A plenary session addressed the Fukushima accident, the related R and D, and future investment. Poster sessions addressed several topics: safety (fire, containment, neutronics, civil engineering, methods), and radiation protection (radionuclide metrology, toxicology, radio-biology, dosimetry).