Complex interactions of rare earth elements in aquatic systems: Comparing observed and predicted cellular responses on Mytilus galloprovincialis

Recent societal and technological developments have led to new sources of contamination, particularly from electronic waste (e-waste). The rapid increase in e-waste, combined with inadequate disposal and recycling practices has resulted in rising levels of hazardous substances in aquatic systems, including rare-earth elements (REEs). However, the effects of REEs on aquatic organisms remain poorly understood. This lack of understanding is concerning since REEs can simultaneously appear in aquatic systems. Thus, this study aimed to evaluate the impacts of Yttrium (Y), Lanthanum (La), and Gadolinium (Gd), individually and as mixtures on the mussel species Mytilus galloprovincialis. Biomarkers related to metabolism, energy reserves, defence enzymes, redox balance, cellular damage, and neurotoxicity were analyzed. The results obtained showed that Y alone caused minimal stress, while Gd, La, and their mixtures induced from moderate to severe stress, increasing metabolic activity, and enzyme responses. This study highlights the ecological impacts of REEs mixtures on aquatic organisms. The complex interactions and additive effects, especially with Gd, underline the need for further research on contaminant mixtures.