ABSTRACT
Due to their exceptional physico-chemical and magnetic characteristics, rare earth (RE) permanent magnets are applied in multiple critical technologies. However, several environmental and economic difficulties arising from obtaining RE elements have prompted the search of alternatives with acceptable magnetic properties but containing a lower percentage of these elements in their composition. The aim of this work was to perform a preliminary toxicological evaluation of three forms of newly developed RE-lean alloys (one NdFeTi and two NdFeSi alloys) applying different in vitro assays, using as a benchmark a commercial NdFeB alloy. Thus, the effects of the direct exposure to powder suspensions and to their derived leachates were analysed in two model organisms (the A549 human cell line and the yeast Saccharomyces cerevisiae) applying both viability and oxidative stress assays. Moreover, the impact of the alloy leachates on the bioluminescence of Vibrio fischeri was also investigated. The obtained data showed that only the direct interaction of the alloys particulates with the applied organisms resulted in harmful effects, having all the alloys a comparable toxicological potential to that presented by the reference material in the conditions tested. Altogether, this study provides new insights about the safety of NdFeTi and NdFeSi alloys.
ABSTRACT
Due to economic, environmental and geopolitical issues, the development of permanent magnets with a composition free of rare earth elements and with acceptable magnetic properties has been considered a priority by the international community, being MnAl based alloys amongst the most promising candidates. The aim of this work was to evaluate the toxicity of powders of two forms of newly developed MnAl(C) permanent magnets through exposure experiments applying three model organisms, using as a benchmark powders of a commercial rare-earth-containing magnet (Nd2Fe14B). For this purpose, the direct exposure to the different particles suspensions as well as to magnets leachates was evaluated. Both viability and oxidative stress assays were applied in an adenocarcinomic human alveolar basal epithelial cell line (A549) and in the yeast Saccharomyces cerevisiae, together with the bioluminescent inhibition assay in the Gram negative bacterium Vibrio fischeri. The obtained results indicate that MnAl(C) permanent magnets, in general terms, presented similar toxicity than the Nd magnet for the selected biological models under the studied conditions. Overall, the presented data provide, for the first time, an in vitro toxicity analysis of MnAl based magnets.
