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.
