Afin d’étudier la santé d’un écosystème marin et le potentiel toxique d’une contamination telle que celle liée à la présence d’hydrocarbures aromatiques polycycliques (HAP), il est nécessaire, outre de connaître les niveaux de contamination du milieu, de pouvoir accéder à la fraction toxique à laquelle les organismes aquatiques ont été exposés et de connaître les effets toxiques des contaminants incriminés. L’exposition et la contamination des organismes aquatiques aux HAP ont généralement été évaluées par le dosage des HAP bioaccumulés dans les tissus. Or, cette approche est critiquable si l'on tient compte des capacités de biotransformation des organismes, notamment des vertébrés, et des propriétés toxiques des produits de transformation formés. Dans ce contexte, l’objectif de cette thèse est d’étudier les phénomènes de bioccumulation et de biotransformation des HAP chez les organismes marins via l’étude des métabolites de HAP. Un effort de validation de biomarqueurs pertinents pour évaluer la génotoxicité des HAP en lien avec la contamination chimique des tissus et la production de métabolites est nécessaire. Des méthodes de dosage des métabolites de HAP dans les matrices biologiques ont tout d’abord été mises au point. Ces outils analytiques sensibles, innovants et performants ont ensuite été appliqués lors d’expositions de poissons à des HAP via différentes voies de contamination en milieu contrôlé. Ils ont permis une meilleure connaissance des phénomènes de biotransformation des HAP. Enfin, des études de terrain ont été réalisées, notamment dans le cadre de l’étude de la contamination de la Baie de Seine, montrant l’applicabilité du dosage des métabolites de HAP dans l’évaluation de l’exposition des organismes aux HAP en milieu naturel. Dans le cadre d’une approche intégrée chimie/biologie, ces travaux ont permis d’apporter une contribution dans le transfert méthodologique des biomarqueurs de génotoxicité des HAP pour des applications en surveillance de l’Atlantique Nord et notamment dans la Manche. / In order to study the health of a marine ecosystem and the toxic potential of a contamination such as that related to the presence of polycyclic aromatic hydrocarbons (PAHs), it is necessary, in addition to the determination of environmental contamination levels, to have access to the fraction for aquatic organisms have been exposed to and to identify the toxic effects of the contaminants. The exposure and contamination of aquatic organisms to PAHs have generally been evaluated by the quantification of bioaccumulated PAHs in tissues. However, this approach is criticable when taking into account the biotransformation capabilities of organisms such as vertebrates and the toxic properties of biotransformation products. In this way, the aim of this study is to study PAH bioaccumulation and biotransformation phenomena through the PAH metabolites study. An effort for the validation of relevant biomarkers to evaluate the link between the genotoxicity of PAHs, PAHs body burden and PAH metabolites production, is necessary. Analytical techniques to quantify PAH metabolites in biological matrices have first been set up. Then, these sensible, innovating and powerful analytical tools have been applied to the study of fish exposures to PAHs through differents contamination sources in controlled conditions. This allowed to have a better understanding of PAH biotransformation phenomena. Finally, field studies have been led, notably to study the contamination of the Seine bay, demonstrating the applicability of the quantification of PAH metabolites to evaluate the exposure and the contamination of organisms to PAHs in natural environment. Within the framework of an integrated approach chemistry/biology, this work led to a contribution in the methodological transfer of biomarkers of PAH genotoxicity

Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The fish products is the most commonly used animal protein in the world. Brazil stands out for pisciculture with emphasis on the production of tilapia (Oreochromis niloticus). Fish farming is subject to attack by pests and pesticide application has been used as a form of control. This work aims at the development of an effective methodology based on the matrix solid phase dispersion (MSPD) and gas chromatography/spectrometry tandem mass (GCMS/ MS) techniques for determination of residues of aldrin, ametrina, bromopropylate, bromuconazole, cypermethrin, chlorpyrifos, chlorpropham, coumaphos, esfenvalerate, etion, permethrin, pirimicarb, pirimiphos methyl, procymidone, vinclozolin pesticides in muscle tissue of tilapia. Therefore, optimization of chromatographic and evaluation of best extraction conditions proposed were performed. The best quantitative response conditions were obtained with 0.25 g of sample homogenized with 0.75 g of adsorbent, using 0.5 g of auxiliary adsorbent, eluted with 5 mL of acetonitrile. The biochar produced from coconut wastes was tested as an adsorbent for DMFS extraction too and presented satisfactory recovery results between 70 ± 1.38% and 120 ± 5.55% at concentration levels 0.02 to 0.1 μg g-1. The parameters evaluated for the validation of the method were: linearity and sensitivity, obtaining a good sensitivity and linear response with coefficients of 0.9999 in the range of 0.01 to 4 μg g-1; selectivity, through matrix effect studies; accuracy and precision with recovery values between 70 - 120% and coefficients ranging from 0 to 16.69% for the concentration levels 0.02 to 0.1 μg g-1 (n = 5) and detection limits and quantification in the range of 0.01 to 0.0009 μg g-1 respectively. The method developed was adequate for the determination of residues of pesticides in samples of tilapia. / O pescado representa a proteína animal mais consumida no mundo. O Brasil se destaca pela prática da piscicultura com notoriedade para a produção de tilápia (Oreochromis niloticus). O cultivo de peixes está sujeito ao ataque de pragas e a aplicação de agrotóxicos tem sido usado como forma de controle. O presente trabalho objetiva o desenvolvimento de uma metodologia eficiente com base nas técnicas de dispersão da matriz em fase sólida (DMFS) e cromatografia gasosa/espectrometria de massas sequencial (GC-MS/MS) para determinação de resíduos dos agrotóxicos aldrin, ametrina, bromopropilato, bromuconazol, cipermetrina, clorpirifós, clorprofam, coumafós, esfenvalerato, etiona, permetrina, pirimicarbe, pirimifós metílico, procimidona e vinclozolina em tecido muscular de tilápia. Para tanto, a otimização das condições cromatográficas e a avaliação da melhor proposta de extração foram realizados. As condições de melhor resposta quantitativa foram obtidos com 0,25 g de amostra homogeneizada com 0,75 g de C18, utilizando 0,5 g de alumina, eluído com 5 mL de acetonitrila. O biocarvão produzido a partir de rejeitos de coco foi também testado como adsorvente para a extração por DMFS e apresentou resultados satisfatórios de recuperação entre 70 ± 1,38% – 120 ± 5,55% para os níveis de concentração 0,02 a 0,1 μg g-1. Os parâmetros avaliados para a validação do método foram: linearidade e sensibilidade, obtendo-se uma boa sensibilidade e resposta linear com coeficientes de 0,9999 no intervalo de 0,01 a 4 μg g-1; seletividade, através de estudos de efeito matriz; exatidão e precisão com valores de recuperação entre 70 - 120% e coeficientes de variação na faixa de 0 a 16,69%, para os níveis de concentração 0,02 a 0,1 μg g-1 (n=5) e limites de detecção e quantificação no intervalo de 0,0009 – 0,02 μg g-1, respectivamente. O método desenvolvido se mostrou adequado para determinação de resíduos de agrotóxicos em amostras de tilápia.