From Biomarkers to Transcriptomics: Assessing the Impact of PFOA, TBBPA, and EE2 on the Sentinel Species Mytilus galloprovincialis

Emerging contaminants, particularly endocrine-disrupting chemicals (EDCs), are in- creasingly detected in marine ecosystems, food, and consumer products, posing risks to both wildlife and human health. Among them, perfluorooctanoic acid (PFOA), tetrabromobisphenol A (TBBPA), and 17α-ethinylestradiol (EE2) stand out due to their environmental persistence, bioaccumulation potential, and ability to interfere with hormonal regulation, oxidative balance, and cellular homeostasis. However, their toxicological effects on marine bivalves, key sentinel species, remain poorly understood. Mussels such as Mytilus galloprovincialis play a central ecological role and are widely used as bioindicators because of their capacity to accumulate contaminants through filter feed- ing. Assessing their biochemical and transcriptomic responses provides critical insight into the sublethal and realistic effects of EDCs at multiple levels of biological organization. This is par- ticularly relevant given the high seafood consumption in Europe, which represents a major human exposure pathway to these contaminants. Laboratory exposures of M. galloprovincialis were conducted using environmentally relevant concentrations of PFOA (1–100 μg·L⁻¹), TBBPA (1–100 μg·L⁻¹), and EE2 (10–300 ng·L⁻¹). A multi-biomarker strategy was applied to evaluate oxidative stress (SOD, CAT, GST, TAC, MDA), protein degradation (UBI), apoptosis (caspase-3), neurotoxicity (AChE), and endocrine disruption (VTG). In parallel, transcriptomic analyses were performed to identify differentially expressed genes and disrupted pathways related to stress responses, detoxification, lipid me- tabolism, and endocrine regulation. The results revealed concentration-dependent alterations in antioxidant defences and cellular homeostasis, with PFOA and TBBPA inducing oxidative stress and apoptosis, while EE2 primarily triggered estrogenic and gametogenic disruptions. Transcriptomic analysis confirmed the modulation of pathways associated with xenobiotic metabolism, energy balance, apoptosis, and non-genomic estrogen signaling. Together, these results indicate that M. gal- loprovincialis exhibits coordinated biochemical and molecular responses upon exposure to EDCs, reinforcing its relevance as a sentinel species. The study highlights potential risks of contaminant biomagnification through the food chain and provides mechanistic evidence to support ecotoxicological monitoring frameworks and regulatory measures aimed at protecting marine ecosystems and public health.