Assessing the impact of Dotarem (a gadolinium-based contrast agent) on the clam Ruditapes decussatus: a...

The present study evaluates the ecotoxicological effects of Dotarem (DOTA), a gadolinium-based contrast agent frequently detected in wastewater, on the marine clam Ruditapes decussatus. Clams were exposed for 7 days to three concentrations of DOTA (C1 = 12.5 µg L^-1, C2 = 25 µg L^-1, C3 = 50 µg L^-1). The study aimed to investigate multiple biomarkers related to physiological, oxidative, neurotoxic, and histopathological responses. Filtration rate was significantly reduced after exposure, from 8.18 ± 4.22 mg h^-1 ind^-1 in controls to 2.03 ± 0.6 mg h^-1 ind^-1 at the highest concentration, indicating impaired feeding activity. Antioxidant enzymes, catalase (CAT), glutathione-S-transferase (GST) and the cellular damage biomarker (malondialdehyde, MDA) displayed concentration- and organ-dependent responses, reflecting oxidative stress induced by DOTA. Acetylcholinesterase (AChE) activity decreased markedly in the gills, independent of dose and showed a dose-dependent inhibition in the digestive gland (p < 0.0001), demonstrating neurotoxic effects. Histopathological analyses revealed lesions in both organs, including cellular infiltrations, vacuolization, and necrosis, with severity increasing with DOTA concentration. Overall, this study highlights that Dotarem acts as a significant environmental contaminant, affecting multiple physiological and biochemical processes in R. decussatus, and emphasizes the need to monitor emerging contaminants in aquatic ecosystems.