Single and combined exposure to cellulose nanofibers and venlafaxine: Effects on Mytilus galloprovincialis embryos

The growing presence of contaminants of emerging concern (CECs) in everyday applications calls for urgent assessment of their impact on environmental and human health. Among these, pharmaceutical active compounds (PhACs) and micro- and nanosized fibers (MNFs) are increasingly detected in marine coastal areas, raising questions about their interactions with marine organisms. This study investigates the impact of two types of cellulose nanofibers, non-oxidized (CNF) and TEMPO-oxidized (TOCNF), and an antidepressant, Venlafaxine (VEN), on the development of the bivalve mollusk Mytilus galloprovincialis . The study aimed to assess the ecotoxicological risk under realistic exposure scenarios considering both acute (48 h) and chronic (7 days) exposure conditions and testing individual CECs as well as their mixture. CNF/TOCNF showed low toxicity, impacting embryo development only at 10 μg/mL and affecting embryo size only during chronic exposure. RhB-labeled CNFs were retained in D-Larvae even after transfer to clean waters. In contrast, VEN influenced embryo development and size from 0.1 μg/mL. When combined, VEN elicited toxicity regardless of the presence of CNFs, although a slight reduction in the percentage of malformed embryos was observed. Overall, these findings provide valuable information into the marine safety of CECs, both individually and in combination, highlighting greater concern for VEN than for CNFs upon release into coastal marine environments.