Features of Microplastics in Seawater, Sediment, and Most Tourists Consumed Marine Fish and Shellfish From Cox's Bazar and Saint Martin's Island, Bay of Bengal, Bangladesh

The present study investigated microplastic (MP) contamination in surface seawater, intertidal sediments, and commercially important fish and shellfish from Cox's Bazar and Saint Martin's Island, two of the most popular tourist destinations in Bangladesh. Seawater and sediment samples were collected from three locations per site, with each site having three replicates. Additionally, seven fish and four crustacean species were obtained from local markets and barbecue shops. MPs were morphologically identified under a stereomicroscope and chemically characterized using Fourier transform infrared spectroscopy (FTIR). The average MP concentrations in surface water were higher at Saint Martin's Island (35.1 ± 29.5 particles L^-1) than at Cox's Bazar (10.45 ± 7.65 particles L^-1). In sediments, concentrations averaged 0.211 ± 0.05 items g^-1 at Cox's Bazar and 0.2055 ± 0.1 at St. Martin's Islands. MP abundance in fish and shellfish was tissue-dependent and varied by location, generally following the order: gut > dorsal muscle > ventral muscle. Overall, mean MP concentrations in the corresponding tissues were higher in samples from Cox's Bazar than in those from St. Martin's Island. Fibers, predominantly black and red (0.1-0.5 mm), were the most dominant form of MPs across all samples. FTIR analysis identified polyethylene terephthalate (53.33%), polyethylene (26.67%), and polypropylene (20%) as major polymer types. The estimated daily MP intake via seafood consumption was highest in adults (74.99 items day^-1) and children (49.99 items day^-1), primarily through the ingestion of Awaous grammepomus. These findings revealed widespread MP contamination in the Bay of Bengal region, underscoring the potential ecological and human health risks associated with it.