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Thesis defense of Maxime Louzon

Maxime Louzon is pleased to invite you to his summer thesis defense Développement d ’’ chemical and biological indicators for the environmental risk assessment of contaminated sites and soils, Friday, October 16, 2020 at 9 a.m. in the Learning Lab room (1st floor) at the IUT (30 avenue de l’Observatoire, 25009 Besançon cedex ).

Given the current pandemic context, the number of people who can attend the defense is severely limited due to the room’s capacity. Consequently, access to the defense is by reservation at the following address: maxime.louzon at univ-fcomte.fr

Invitation to download HERE

Composition of the jury

Rapporteur: Isabelle Lamy, DR HDR, INRAE, Versailles
Rapporteur: Franck Vandenbulcke, PU HDR, University of Lille, Lille
Examiner: Carole Cossu-Leguille, PU HDR, University of Lorraine, Metz
Examiner: Aurélie Droissart-Long, Doctor of Pharmacy, INERIS, Verneuil-en-Halatte
Examiner: Pierre-Marie Badot, PU HDR, University of Franche-Comté, Besançon
Thesis supervisor: Annette de Vaufleury, MCF HDR, University of Franche-Comté, Besançon
Co-thesis supervisor: Benjamin Pauget, R&D Manager (PhD), TESORA, Arcueil
Co-thesis supervisor: Frédéric Gimbert, MCF, University of Franche-Comté, Besançon
Guest member: Cécile Grand, Project Engineer (PhD), ADEME, Angers
Guest member: Hubert Leprond, Expert in Soil and Groundwater Management, EDF, Saint-Denis

Summary
As part of the sustainable management of polluted sites and soils (SSP), the general objective of this thesis was to improve environmental (ERE) and health (ERS) risk assessments. Internal reference concentrations (TGV) were determined ex situ in the snail Cantareus aspersus for metals (loïde) s, polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls, as well as global indicators, such as as the ex situ indices of the sum of excess transfers (GSET) and ecotoxicological risks (GERITOXE). These indicators were applied to 68 variously contaminated soils and showed that it is not necessarily the most contaminated soils that present the highest risks. It has been shown that the excess metal transfers (loïde) s for the snail are, unlike the non-anomalous transfers from the pedogeochemical background, more influenced by the total concentration than by the physicochemical properties of the soils. Beyond these influences, there was also the question of the influence of site specificities on the bioavailability of contaminants for the snail. This was investigated in an inter-laboratory test leading to the standardization of the in situ and ex situ approaches (ISO 24032) with which we have shown that the transfers are generally higher ex situ than in situ , except for some metals (eg, Cd and Mo). We were thus able to discern the respective interests of the ERE methods in situ and ex situ and the answers obtained according to scientific questions and management perspectives. The search for links between the bioavailable concentrations and specific ecotoxicological effects of the snail was carried out at different levels of organization (life history traits and genome stability) to refine the interpretation of the overall indicators developed. The relevance of the coupling of the micronucleus test with the random amplification technique of polymorphic DNA for an assessment of genotoxicity in hemocytes was highlighted. The study of telomere dynamics in snails has been developed and has revealed original patterns. Strong telomere attrition during growth from juvenile to subadult stage was characterized, followed by maintenance of telomere length during adulthood. Although genotoxic damage is identified and associated with alterations in the health of snails exposed to soil contaminated with metals and PAHs, their telomeres are not shortened in hemocytes. In the context of the applicability of the One health initiative to the management of PHC considering human health and environmental health, the study of exposures via the relationships between bioaccessibility for humans and bioavailability for Soil As, Cd and Pb snail showed strong convergences. Regarding the links between the levels of risk, it has been shown that soils identified as "at risk" for human health could present a low or no transfer of contaminants to the snails and therefore an absence of environmental risk, offering alternative management perspectives. In conclusion, the results obtained open up new avenues for the research of the fundamental relationships between environmental and toxicological bioavailability at different levels of biological organization and the identification of the respective interests of field and laboratory approaches in the context of risk assessments. depending on management issues. Approaches allowing to combine environmental and health assessment methodologies are proposed in order to better manage environmental pollution. Finally, the indicators developed in the context of this thesis strengthen the positioning of the chemical and biological characterization tools targeted at the site level.

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