Bioaccumulation and toxicological risks of tris(2-ethylhexyl) trimellitate (TOTM) plasticiser in oysters: implications for marine ecosystem health

Abstract

Despite growing concerns over phthalates, the environmental fate and biological impact of alternative plasticisers such as tris(2-ethylhexyl) trimellitate (TOTM) remain underexplored. This study assessed TOTM bioaccumulation and toxicological responses in Crassostrea (Magallana) saidii following 21-day exposures at 10 and 100 µg/L. TOTM was found to bioaccumulate in oysters in a concentration- and time-dependent manner, highlighting its persistence in marine ecosystems. Exposure to TOTM induced oxidative stress, evidenced by an immediate increase in superoxide dismutase (SOD) activity, followed by inhibition at 100 µg/L. Catalase (CAT) activity was significantly inhibited in all exposure groups, with partial recovery observed at 10 µg/L but further inhibition at 100 µg/L. Reduced glutathione (GSH) levels increased in a dose-dependent manner, with the highest level of 219 mmol/g protein in the 100 µg/L group on day 21. Lipid peroxidation, indicated by elevated malondialdehyde (MDA) levels, was observed, with the highest level of 1.89 µmol/g protein detected in the 10 µg/L group, followed by 1.67 µmol/g protein in the 100 µg/L group. Histopathological examination revealed marked tissue alterations, including gill ciliary deterioration, mantle epithelial disruption, and atrophy of the digestive gland. Collectively, these findings demonstrate that TOTM, despite its classification as a safer alternative plasticiser, can induce sublethal yet ecologically relevant stress responses in marine bivalves. The observed bioaccumulation and impairment of antioxidant and digestive functions highlight the need to re-evaluate current assumptions regarding the environmental safety of non-phthalate plasticisers.