From High-Tech To High-Risk? Unveiling the Acute Ecotoxicological Effects of Rare Earth Elements on Daphnia magna.

Technological advancement has brought significant environmental challenges, as its associated waste is difficult to manage and its long-term effects on ecosystems and biota remains uncertain. This study aimed to evaluate the acute toxicity of rare earth elements (REEs): lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium on the standard aquatic species Daphnia magna through a toxicity screening approach. Based on EC₅₀ values, the most toxic element was yttrium (EC₅₀ = 7.2 mg L^-1), followed by scandium, dysprosium, europium, lutetium, neodymium, holmium, gadolinium, ytterbium, thulium, terbium, samarium, cerium, and lanthanum (10 > EC₅₀ < 100) identified as harmful, and praseodymium classified as non-toxic with an EC₅₀ above 100 mg L^-1 (130.81 mg L^-1). This study demonstrates that all REEs, except praseodymium, induce acute effects in D. magna using ASTM as a culture medium. The results also highlight the need for standardized screening studies to obtain reliable data for both predictive and retrospective environmental risk features.