Behaviour of ceria nanoparticles in standardized test media - influence on the results of ecotoxicological tests

International audienceThe main objectives of this work were to establish the behaviour of a ceria nanopowder in different ecotoxicological media commonly used in standardized aquatic ecotoxicity tests and consequently to assess the acute and chronic ecotoxicity in two microinvertebrates: Daphnia magna and Ceriodaphnia dubia and in a freshwater green algae: Pseudokirchneriella subcapitata. Different approaches to disperse the ceria nanoparticles (i.e. stirring, use of probe sonication, addition of humic acids) were tested and the influence on the biological endpoints was investigated. Despite the agglomeration phenomena observed in all the tested media, the results obtained indicated higher stability in the lower ionic strength media with addition of humic acid (2 mg.L-1, TOC). No acute toxicity were observed with D. magna, whatever the dispersal method performed and the nCeO2 concentration tested (up to 1000 mg.L-1), as no acute toxicity was recorded with C. dubia following exposure to the stirring suspensions. On contrary, acute toxicity was recorded in C. dubia with EC50 values comprise between 11.9 and 25.3 mg.L-1 using the probe sonicated suspension with or without humic acids addition. Significant chronic effect on the reproduction capability was also recorded in C. dubia. The estimated EC10 values were comprised between 2.1 and 2.9 mg.L-1. Focusing on P. subcapitata, despite the different agglomerate size recorded in the tested media at the end of the exposure periods, results obtained were similar. Adverse effect on algal growth around 5 mg.L-1 were reported (mean EC10 = 4 +- 1.8 mg.L-1). Those results suggested the needed for standardized testing protocol concerning the aqueous media used or the sample preparation for laboratory testing

Effet des nanoparticules sur Gammarus sp (Amphipoda) et sur ses performances fonctionnelles

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Multibiomarker assessment of the long term effects of dissolved and nanoparticulate silver (nAg) on zebra mussels: influence of feeding

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Multibiomarker assessment of cerium dioxide nanoparticle (nceo2) sublethal effects on the freshwater invertebrates Dreissena polymorpha and Gammarus roeseli

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MultiXenobiotic Resistance (MXR) vs Nanoparticles: is MXR a good biomarker of exposure? A study with zebra mussels and gammarids exposed to silver and titanium dioxide nanoparticles

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Nanoparticules : comment évaluer leurs effets potentiels sur les milieux aquatiques ? Synthèse des avancées du programme MESONNET

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Ecotoxicity of environmentally realistic silver nanoparticle concentrations: from individual to functional impacts on Gammarus sp (Amphipoda)

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Individual and functional impacts of environmentally realistic silver nanoparticle exposures on Gammarus sp (Amphipoda)

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Integrated assessment of ceria nanoparticle impacts on the freshwater bivalve Dreissena polymorpha

International audienceExposures in realistic environmental conditions are essential to properly assess the effects of emerging pollutants on ecosystems. While ceria nanoparticles (nCeO 2) production and use are expanding quickly, ecotoxicity studies remain very scarce. In this work, we set up experimental systems reproducing a simplified ecosystem to assess the effects of a chronic exposure to citrate-coated nCeO 2 (ci-CeO 2) and bare nCeO 2 (ba-CeO 2) on the freshwater mussel Dreissena polymorpha using an inte‐ grated multibiomarker approach. The fate of nanoparticles was tightly monitored to properly characterize the exposure. Organisms were exposed for three weeks and sampled weekly for biomarker analysis. Mussel filter-feeding activity resulted in significant removal of nCeO 2 from the water column. At the same time, bioaccumu‐ lation was low, reaching its maximum in the first week. Mussels bioaccumulated ci-CeO 2 three times more than ba-CeO 2 , probably due to coating-related differences in their behavior in the water column and in organisms. Meanwhile, biomarker results were integrated and synthesized using linear discriminant analysis, highlighting that pi-glutathione-S-transferase (piGST) mRNA, catalase (CAT) activity, and lysosomal system were the most impacted of the seven biomarkers singled out by the discriminant analysis. These biomarker responses indicated that mussels exposed to both forms of nCeO 2 were stressed and differentiate from the controls. Moreover,theyresponded differently to ba-CeO 2 and ci-CeO 2 exposure. How‐ ever, biomarkers used in the experimental conditions of the present study did not indicate severe nCeO 2 toxicity on mussels, as cellular damage biomarkers and mussel filtering activity were left unimpaired. However, further studies are needed to investigate if the slight perturbations observed could lead to populational impacts in the long-term