Toxicity of lanthanides on various fish cell lines

The growing use of Lanthanides in new technologies has increased their anthropogenic releases into the aquatic environment over the last decades. However, knowledge on their ecotoxicological impacts is still incomplete, especially with regard to biological effects of Lanthanides mixtures and the possible regular variation in toxicity along the Lanthanides series. The present study evaluated the individual toxicity of all Lanthanides and the toxicity of mixtures of three of them, namely Neodymium (Nd³⁺), Gadolinium (Gd³⁺), and Ytterbium (Yb³⁺) on Danio rerio fibroblast-like cells (ZF4). Individual and mixtures toxicity of Neodymium (Nd³⁺) and Ytterbium (Yb³⁺) were also assessed on Danio rerio hepatic cells (ZFL) and Oncorhynchus mykiss epithelial cells (RTgill-W1). The measured Lanthanide concentrations were close to the nominal ones in the culture media of ZF4, ZFL, and RTgill-W1 cells (85-99%). A toxic impact was observed on the three fish cell lines exposed to all Lanthanides tested individually. RTgill-W1 appeared as the less sensitive cells, compared to the two others. Four Lanthanides, Erbium (Er³⁺), Thulium (Tm³⁺), Ytterbium (Yb³⁺) and Lutetium (Lu³⁺) showed a higher toxicity than the others on ZF4 cells but no correlation could be established between the toxicity of Lanthanides and the order of the elements within the Lanthanides series. Exposures to binary mixtures highlighted the presence of synergistic effects on cell viability for all cell lines.