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

Abstract

Exposures in realistic environmental conditions are essential to properly assess the effects of emerging pollutants on ecosystems. While ceria nanoparticles (nCeO₂) production and use are expanding quickly, ecotoxicity studies remain very scarce. In this study, we set up experimental systems reproducing a simplified ecosystem to assess the effects of a chronic exposure to citrate-coated nCeO₂ (ci-CeO₂) and bare nCeO₂ (ba-CeO₂) on the freshwater mussel Dreissena polymorpha using an integrated multibiomarker approach. The fate of nanoparticles was tightly monitored to properly characterize the exposure. Organisms were exposed for 3 weeks and sampled weekly for biomarker analysis. Mussel filter-feeding activity resulted in significant removal of nCeO₂ from the water column. At the same time, bioaccumulation was low, reaching its maximum in the first week. Mussels bioaccumulated ci-CeO₂ three times more than ba-CeO₂, 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 nCeO₂ were stressed and differentiate from the controls. Moreover, they responded differently to ba-CeO₂ and ci-CeO₂ exposure. However, biomarkers used in the experimental conditions of this study did not indicate severe nCeO₂ 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.

Keywords:

• Ceria nanoparticle
• discriminant analysis
• Dreissena polymorpha
• multibiomarker approach

Acknowledgements

This study is a contribution to the Labex Ressources 21, ANR-10-LABX-21-01 (Strategic metal resources of the 21st century). Sharon Kruger is gratefully acknowledged for her English corrections.

Declaration of interest

Financial supports were provided by the French National Agency (ANR-10-NANO-0006/MESONNET project) for M. Garaud Ph.D. salary and running costs and CPER Lorraine-ZAM (Contrat Projet Etat Région Lorraine, Zone Atelier Moselle). It is not necessary for University, CNRS or ANR to review, comment or approve their manuscript before publication. The authors gratefully acknowledge CNRS for funding the iCEINT International Consortium for the Environmental Implications of NanoTechnology. We did not receive writing assistance; Sharon Kruger just reviewed the English version of the manuscript.

Supplementary material available online

Supplementary Tables S1–S7 and Figure S1