Evaluation of toxicity profiles of rare earth elements salts (lanthanides)

The presented study aims to extend the knowledge of toxicological profile of rare earth elements salts (REEs). The basal toxicity test performed comprised assessment of cytotoxicity (3T3 Balb/c Neutral Red Uptake Test) that allows for calculation of LD50 (rats) on the basis of the concentration which leads to a 50% reduction in cell growth (IC50). Environmental toxicity was addressed by the Tubifex tubifex (T.t.) express test. The in vitro skin irritation (OECD TG 439) and skin corrosion tests (OECD TG 431) utilizing the 3D in vitro reconstructed human epidermal model EpiDerm (MatTek IVSL, SK) were used for assessment of skin irritation and corrosion potential hazard of REEs. Mutagenic effects were determined using the bacterial reverse mutation assay (Ames Test) on 5 Salmonella typhimurium strains with and without metabolic activation (OECD TG 471). Endocrine disruption was evaluated by means of a yeast-based assay YES/YAS (Xenometrix, CH). Skin sensitization was assessed using the LuSens assay, based on a genetically modified human keratinocyte cell line (OECD TG 442D). The tested REEs have no potential of mutagenicity or skin sensitization, exhibit very weak endocrine disruption potential and only exceptional local irritation/corrosion effects for thulium (III) chloride anhydrous, but have acute and chronic toxic effects on the aquatic environment.