Genotoxicity in humans and indicator species exposed to uranium wastes

The risks of uranium mill tailings are associated with their content in metals and radionuclides, raising concern among the general public and governmental authorities. Human and other living species from uranium mining districts may be exposed to radiation doses emitted by wastes; radioactive dust and contaminated water and foodstuffs. The determination of the risks of such hazards is usually carried out through chemical analysis of environmental samples, neglecting the assessment of its biological effects. The measurement of the biological effects of pollutants has become of major importance for the assessment of the quality of the environment, in order to provide indications of harmful effects on biota and to complement the information given by chemical analyses of environmental samples. Such scenario, have triggered the research to establish early warning signals of adverse biological responses to environmental toxins, named biomarkers, to be used as a tools for environmental quality assessment. In this work different exposure-related molecular and cellular responses were analyzed in earthworms, wood mice and humans, aiming for the determination of the chemical and radiological risk of the residues from the Cunha Baixa uranium mine, to indicator species and populations living nearbyand also to clarify underlying responses to metals and radionuclides exposure, pointing out for the development of potentially new molecular biomarkers.For that, earthworms were exposed for 56 days in the laboratory and in situ to contaminated soil from the Cunha baixa uranium mine and several parameters were assessed, like growth, reproduction, metals and radionuclides bioaccumulation, histopathology, DNA damages, cytotoxicity and gene expression profile. Wood mice were sampled in the Cunha Baixa uranium mining area and in a reference area to determine DNA damages, expression levels and mutations in tumour suppressor genes and also metals bioaccumulation. Blood samples were colleted from healthy individuals from the population living near the Cunha Baixa uranium mine, for DNA damages assessment, immunophenotyping and for the determination of the presence of trace elements. Results showed that earthworms and wood mice were negatively affected by the exposure to the uranium mining residues at all the biological levels of organization tested in this work, making them good indicator species for the determination of the risks of such contaminated areas, highlighting the potential risks associated with the exposure to these contaminants. Moreover, the study performed to the population of Cunha Baixa reveled DNA damages and depletion of important immune cell populations (mainly, T and NK lymphocytes), potentially due to the exposure to the radioactive mine residues, increasing the susceptibility for tumour growth.The present study contributed greatly for the characterization of the risks posed by the exposure to residues from abandoned uranium mines, highlighting the damaging effects at a molecular and cellular level, which potentially may cause genomic instability and increased risk of the organisms exposed to them, of developing genetic diseases