PhD thesis defense of Alice Vidal

Abstract

Poly- and per-fluorinated substances (PFAS), exclusively derived from anthropogenic activity, are nowadays widely used for industrial and domestic purposes. During their synthesis, PFAS are released in the atmosphere as well as in aquatic and terrestrial compartments. Environmental distribution studies are relatively recent and have shown the bioaccumulation of some PFAS in aquatic vertebrates. Physico-chemical properties of PFAS lead to a specific toxicokinetic (TK) profile. Although TK studies on these compounds are becoming more and more abundant, some mechanistic challenges still need to be solved for aquatic vertebrates, particularly for absorption, distribution and elimination processes. In order to improve this knowledge, a physiologically based toxicokinetic (PBTK) model has been developed to describe the fate of three PFAS belonging to the perfluoroalkyl family: perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) and perfluoronanoic acid (PFNA). This PBTK model was parametrized with rainbow trout (Oncorhynchus mykiss) physiological parameters. Next, it was used to test several mechanistic hypotheses about PFAS bioaccumulation, useful for improving the risk assessment of these chemicals. Fish growth and water temperature are key factors in the TK for poikilotherms. So, they have been integrated in the model. Three experiments of dietary exposure to PFOS, PFHxS and PFNA at different temperatures (7°C, 11°C and 19°C) have been performed. They allowed (i) to measure concentrations in organs of interest and (ii) to calibrate and evaluate the model predictions.