Unveiling Microplastics in Commercial Brackish Water Fishes from the Lower Meghna River Estuary of Bangladesh

Microplastics (MPs) pose a persistent global threat and have entered almost every component of the ecosystem and seafood items. This study aimed to identify and characterize MPs in three widely edible fishes in the lower Meghna River estuary of Bangladesh and assess the polymer hazard index. Gastrointestinal tracts (GIT) of fish were collected and digested with KOH to extract MPs, and the polymer was confirmed by FTIR analysis. The species with the highest mean MP abundance was M. gulio (22.89 ± 8.91 MPs/GIT), followed by P. paradiseus (10.78 ± 4.29) and O. pama (15.11 ± 3.55). Fibers were predominant MPs, comprising 73.20-91.75% of the total particles. Blue, red, and black were the dominant colors of MPs, while 81.07-93.81% particles were between 500 and 1000 μm. Five distinct polymers, polypropylene, polyethylene, polyethylene terephthalate, Polystyrene, and Nylon 6, were detected in the GIT of these fishes. The study unveiled a significant correlation (r² = 0.223, p = 0.013) between MP incidence and the total length of fish. The polymer hazard index of the selected fishes showed the risk category IV (Danger), which is alarming. A risk category IV indicates that exposure to polymer, directly or indirectly through the food chain, may result in severe health consequences for humans as well as wildlife. With these detailed insights into MPs in most consumable fishes, the study highlights the comprehensive risks posed by MPs that could be useful for strategies to mitigate this environmental challenge.