Les additifs issus des microplastiques : caractérisation, lixiviation et impacts

Environmental pollution from plastics and microplastics is a threat to the environment and wildlife on multiple aspects regarding exposition of different hazards. One of them is due to the chemical impact of plastic additives. The interest of studying plastic additives is growing since the use of such molecules has become controversial as many of them are considered as toxic for organisms, human beings, and have been found in the marine ecosystem. The impact and the extent of this pollution is not fully understood because of the lack of methods able to comprehensively analyze the wide diversity of plastic additives. This PhD thesis aimed to gain a better understanding of the chemical impact of organic plastic additives (OPAs) in marine organisms. First, a general method, for identying a selection of OPAs, was successfully developed using pyrolysis/thermal desorption-gas chromatography coupled to a high-resolution mass spectrometer (Py/TD-GC-HRMS). In parallel, a high-resolution mass spectra database was implemented. Consecutively, the method was applied to characterize OPAs into petro- and biobased plastic samples including polypropylene (PP) and polylactic acid (PLA) plastic containers from two distinct suppliers. The results showed that all samples contained additives including plasticizers (phthalates, adipates), phosphorus flame retardants, antioxidants and UV stabilizers (benzotriazoles and benzophenones). Considering the additives content of the samples and the high presence of plastic food containers in aquatic environment, a final experiment focused on the potential impact of these additives. To do so, the ecotoxicological profile of the leachate of these samples were investigated using in vitro short-term bioassays i.e. (i) baseline toxicity (Microtox® test) on A. fisheri, and (ii) Pacific oyster (C. gigas) fertilization success and embryo-larval development. Nevertheless, no significant toxic effects was observed upon exposure to the leachates. Overall, this work proposed a rapid and general method for the identification of a large diversity of OPAs. Furthermore, the results highlighted the heterogeneity of the chemical signatures of plastic materials between suppliers and within the same polymer. This fact complicates the toxicological and ecotoxicological assessment of plastic materials made of the same polymer that may have different additive profiles.