Environmental fate and ecotoxicity of lanthanides: Are they a uniform group beyond chemistry?

• Published in: Environment international 2014-10, Vol.71, p.148-157
• Main Authors: Gonzalez, Veronica, Vignati, Davide A.L., Leyval, Corinne, Giamberini, Laure
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; Biological Availability; Continental interfaces, environment; Ecotoxicity; Ecotoxicology - methods; Ecotoxicology - trends; Ecotoxicology, biological effects of pollution; Environment; Environmental Sciences; Fundamental and applied biological sciences. Psychology; Humans; Invertebrates - drug effects; Invertebrates - metabolism; Lanthanides; Lanthanoid Series Elements - chemistry; Lanthanoid Series Elements - pharmacokinetics; Lanthanoid Series Elements - toxicity; Risk Assessment - methods; Sciences of the Universe; Soil - chemistry; Terrestrial environment, soil, air
• ISSN: 0160-4120; 1873-6750
• DOI: 10.1016/j.envint.2014.06.019

Lanthanides are a chemically uniform group of metals (La–Lu) that, together with yttrium (Y) and scandium (Sc), form the group of rare earth elements (REEs). Because of their many applications (e.g., agriculture, medicine, motor industry), their global production has increased exponentially in the last decades and their biogeochemical cycles are being disrupted by human uses (e.g., gadolinium anomalies in freshwater and tap water, REEs enrichment of soils as a consequence of agricultural practices). However, ecotoxicological effects and mechanism of action of these elements are still poorly understood. In particular, there is no consensus as to lanthanides showing a coherent and predictable pattern of (eco)toxicity in the same way as their atomic properties. For aquatic organisms, contradictory conclusions on this issue can be found in the bibliography. This review shows that the variable composition of culture media used in ecotoxicology, and the associated differences in lanthanide's speciation, are the most likely cause for such discrepancies. In particular, the formation of insoluble species in some highly complexing media likely leads to changes in the soluble concentration of lanthanide during some tests; with the potential for a generalized underestimation of their toxicity at the present state of knowledge. For terrestrial organisms, suitable studies to establish trends in lanthanides' toxicity are practically nonexistent; with most research focusing on the effects of REE mixtures. Molecular level studies to elucidate the mechanisms of action of lanthanides are essentially limited to La, pointing to the need for further research to identify common mechanisms of action or modes of action across lanthanides. Overall, agreement on the correct procedures to follow to obtain reliable and comparable data for individual lanthanide is the first action to take in order to arrive at a reliable risk assessment for this group of elements in both aquatic and terrestrial systems. •Ecotoxicity of lanthanides (Ln) is strongly influenced by exposure media composition.•The correct procedures to follow should be defined to obtain comparable data.•At present, no single theory is capable of accommodating all experimental data.•For terrestrial organisms, most research focus on the effects of Ln mixtures.•Studies to elucidate the mechanisms of action of Ln are essentially limited to La.