Elastomer leachates modulate haemocytes responses in Mytilus edulis

Rubber pollution is widespread in aquatic environments, where hazardous additives used in manufacturing pose serious risks to aquatic life. Both natural and synthetic rubbers undergo vulcanization, incorporating stabilizers to enhance durability and elasticity, alongside additives like antioxidants, antimicrobials, cross-linking agents and pigments. These substances, not chemically bound to the rubber polymer matrix, can leach into aquatic systems and interact with biota. Thus, this study investigated the ecotoxicological effects of rubber leachates from commercial products, specifically balloons (BAL) and dishwashing gloves (DG), on Mytilus edulis haemocytes. After 24 h of exposure, flow cytometry revealed several toxic effects, including reduced cell viability, metabolic activity, lysosomal content, and neutral lipid levels, as well as DNA alterations indicative of apoptosis. Mitochondrial dysfunction was evidenced by altered membrane potential and reduced reactive oxygen species (ROS) formation, while cytoplasmatic effects included decreased ROS levels and membrane depolarization. Mechanistically, the observed toxicity is likely driven by metabolic and membrane disruption, as well as mitochondrial dysfunction. Chemical analysis tentatively identified several hazardous organic compounds, including cyclic amines, benzothiazoles, and elevated zinc concentrations, known disruptors of cellular homeostasis. This study highlights the sublethal impacts of rubber-derived pollutants on mussel immune cells, providing mechanistic insight into how chemical additives associated with consumer rubber products may pose a threat to the health of marine organisms.