No / Drinking water disinfection byproducts (DBPs) are generated by the chemical disinfection of water and may pose a hazard to the public health. Previously we demonstrated that iodoacetic acid was the most cytotoxic and genotoxic DBP analyzed in a mammalian cell system. Little is known of the mechanisms of its genotoxicity. The involvement of oxidative stress in the toxicity of iodoacetic acid was analyzed with the antioxidants catalase and butylated hydroxyanisole (BHA). Iodoacetic acid toxicity was quantitatively measured with and without antioxidants in Salmonella typhimurium strain TA100 and with Chinese hamster ovary (CHO) cells. The endpoints included cytotoxicity in S. typhimurium or in CHO cells, mutagenicity in S. typhimurium, and genotoxicity in CHO cells. Neither catalase nor BHA reduced the level of iodoacetic acid induced cytotoxicity in S. typhimurium. In CHO cells neither antioxidant caused a significant reduction in iodoacetic acid induced cytotoxicity. However, in S. typhimurium, BHA or catalase reduced the mutagenicity of iodoacetic acid by 33.5 and 26.8%, respectively. Likewise, BHA or catalase reduced iodoacetic acid induced genomic DNA damage by 86.5 and 42%, respectively. These results support the hypothesis that oxidative stress is involved in the induction of genotoxicity and mutagenicity by iodoacetic acid.

L’écotoxicité de nanoparticules de dioxyde de cérium (CeO2 NP) en milieu dulçaquicole a été évaluée à l’aide (i) d’essais monospécifiques standardisés et (ii) de chaînes trophiques expérimentales exposées en microcosme. Aucune toxicité n’a été observée chez Nitzschia palea et Chironomus riparius en conditions monopsécifiques. Une inhibition de croissance a été observée chez les amphibiens Xenopus laevis et Pleurodeles waltl., ainsi qu’une toxicité aiguë chez le xénope et une génotoxicité dose-dépendante chez le pleurodèle. Les expositions en microcosme ont mis en évidence une toxicité aiguë chez le pleurodèle, des modifications des communautés bactériennes, une diminution de la décomposition de la litière, ainsi que des effets tératogènes chez le chironome. Les effets observés varient suivant la nature des CeO2 NP étudiées. L’utilisation d’un système biologique complexe permet l’étude des mécanismes de toxicité dans des conditions plus représentatives des conditions environnementales. / The ecotoxicity of cerium dioxide nanoparticles (CeO2 NPs) was studied on freshwater organisms (i) in standardized monospecific conditions and (ii) on experimental trophic chains exposed in microcosms. No toxicity was observed on Nitzschia palea and Chironomus riparius in monospecific conditions. Growth inhibition was observed on the amphibian species Xenopus laevis and Pleurodeles waltl., as well as acute toxicity and dose-dependent genotoxicity observed on Xenopus and Pleurodeles, respectively. Microcosm experiments revealed acute effects on Pleurodeles, changes in bacterial communities, a decrease in leaf litter decomposition and teratogenicity on chironomids. The observed effects vary depending on the type of CeO2 NPs. The use of complex biological system enables the study of toxicity mechanisms in environmentally relevant conditions.