Toxicity of CeO 2 nanoparticles at different trophic levels – Effects on diatoms, chironomids and amphibians Agathe Bour, Florence Mouchet ⇑ , Laurent Verneuil, Lauris Evariste, Jérôme Silvestre, Eric Pinelli, Laury Gauthier Université de Toulouse, UPS, INP, EcoLab (Laboratoire d’écologie fonctionnelle et environnement), ENSAT, Avenue de l’Agrobiopôle, F-31326 Castanet-Tolosan, France CNRS, EcoLab (Laboratoire d’écologie fonctionnelle et environnement), F-31326 Castanet-Tolosan, France highlights  The ecotoxicity of two types of CeO 2 nanoparticles was studied.  No toxicity was observed on diatoms or chironomid larvae.  Amphibian larvae exhibited mortality, growth inhibition and genotoxicity.  Toxicities were different depending on the species and the type of NP. article info Article history: Received 21 February 2014 Received in revised form 26 June 2014 Accepted 3 July 2014 Handling Editor: A. Gies Keywords: Ecotoxicity Cerium nanoparticles Aquatic invertebrates Amphibians Algae abstract The aim of the present work is to provide wider information on the toxicity of cerium dioxide nanoparticles (CeO 2 NPs) in aquatic environments, by studying the toxicity of two types of CeO 2 NPs for four species (diatoms Nitzschia palea, the sediment-dwelling invertebrate Chironomus riparius, and the amphibian larvae Xenopus laevis and Pleurodeles waltl.). The two types of CeO 2 NPs have different intrinsic properties: some of them are small citrate-coated spheres (2–5 nm), and the others are larger uncoated plates (20–60 nm). Acute toxicity (mortality at 48 or 96 h, depending on the test-organism) was assessed for the four species, from 0.1 to 100 mg L 1 of NPs. Sub-lethal effects were assessed on chir- onomids exposed between 0.01 and 1 mg L 1 of NPs. Mortality, growth inhibition and genotoxic effects were evaluated on amphibian larvae from 0.1 to 10 mg L 1 . Results reveal that no acute toxicity occurs on any species after short exposures, even at the highest concentrations. Mortality (35%) is observed on Xenopus larvae after 12 d of exposure at the highest concentration of one type of NPs. No significant effects were observed on chironomids during chronic exposure. Xenopus larvae growth was inhibited from 1 mg L 1 of both NPs while growth inhibition is observed on Pleurodeles only at the highest concentration of one type of NPs. No genotoxicity was observed on Xenopus but Pleurodeles exhibited dose-dependent genotoxic effects when exposed to one type of NPs. Observed differences in toxicity are discussed focusing on the studied compartment, routes of exposure, species and NPs. Ó 2014 Published by Elsevier Ltd. 1. Introduction In recent years, an explosion in nanoparticles (NPs) production and use has taken place. These particles of less than 100 nm have unique physical and chemical properties, making them extremely attractive for applications in many consumer products (The Royal Society, 2004) or for military or medical purposes (Huang et al., 2011; Shao et al., 2011). It is thus very likely that a non-negligible part, directly released during their life cycle, enters the environment (Keller et al., 2013). However, environmental impacts of such releases are still relatively unknown. If no strict regulations are currently effective concerning NPs, several recommendations are already available for industry and toxicological testing (FDA, 2012a,b; OECD, 2010a). The OECD also published a priority list for the testing of representative manufactured nanomaterials (OECD, 2010b), on which cerium dioxide nanoparticles (CeO 2 NPs) appear. Indeed, despite their important volume of production and use (fuel additives, coating, catalysis, cosmetics, etc.), there is a lack of information concerning their toxicity. Studies on CeO 2 NP ecotoxicity have been emerging these last few years, with differ- ent biological models: bacteria (Thill et al., 2006), terrestrial http://dx.doi.org/10.1016/j.chemosphere.2014.07.012 0045-6535/Ó 2014 Published by Elsevier Ltd. ⇑ Corresponding author at: EcoLab, Campus ENSAT, Avenue de l’Agrobiopôle, 31326 Castanet-Tolosan, France. Tel.: +33 (0)5 34 32 37 56. E-mail address: florence.mouchet@ensat.fr (F. Mouchet). Chemosphere 120 (2015) 230–236 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere