Browsing by Author "Psyrillou, Anna Magdalini"

Although hot particles can be released to the environment via many pathways (nuclear accidents, warfare, industry), the understanding of their behavior in the human body, as well as their consequent health impacts. This study aims to understand how uranium particles (UO2 particles) and particles derived from nuclear accidents (Cesium-rich Micro-Particles, CsMPs) behave chemically after inhalation and how they impact human lungs. Specifically, the study aims to ascertain the duration of particle persistence within tissues post-inhalation, investigate the likelihood of translocation or chemical modifications, and evaluate both the chemical and possible radiobiological risks posed to organisms. To achieve this objective, the physicochemical alterations of UO2 particles and CsMPs after exposure to simulated lung fluids and their resulting cytotoxicity in cell models are studied. Dissolution studies are conducted, first using simulated lung fluid (SLF), that represents the interstitial lung fluid in the lung alveolar, followed by artificial lysosomal fluid (ALF), which mimics the conditions particles encounter after internalization by alveolar macrophages. Particle solubility is assessed using chemical analytical techniques (ICP-MS). Thus, the potential dissolution of these particles or their ability to persist as intact point sources of radiation over extended periods is explored. Particles after dissolution are examined using SEM-EDX analysis to study changes in the surface morphology and chemical composition. Additionally, the initial uptake and cytotoxic effects of these particles is investigated using murine lung fibroblast and macrophage cell lines, aiming to establish a detailed understanding of their radio- and chemical toxicity. UO2 particles presented minimal dissolution in SLF(< 2% of U dissolved) during 60 days of dissolution and a formation of a secondary phase on the surface of the particle was observed (mineral of uranyl associated with phosphates, most likely autunite). After exposure to ALF for 30 days, UO2 particles dissolved extensively ( ̴ 90% of U dissolved). From the single-particle dissolution for the CsMPs generated from the Fukushima-Daiichi accident, preliminary data has shown that within 30 days, a range of 10-25% of Cs-137 was leached into the SLF solution. Modified UO2 (after dissolution in SLF for 10 days, 180 days or ALF for 30 days) shown similar cell cytotoxicity profile as unmodified UO2 particles (20-40% cell viability after 24 hours).