Microplastic ingestion and potential risk assessment on commercial and non-commercial marine fish in the Bay of Bengal

Microplastic contamination and potential risk assessment in coral reef fish species have been under-studied, particularly in the Bay of Bengal. Quantification and characterization of microplastics and their potential health risks were assessed for six tropical fishes from Saint Martin's Island, Bay of Bengal. A total of 60 gastrointestinal tracts (GIT) from six fish species (10 individuals/species) were collected and digested with 20 mL of 65% concentrated HNO₃ + 80 mL of distilled water at 70 °C for 3 h, and microplastics were extracted by density separation using 4.4 M, 1.5 g/mL of sodium iodide solution. Microplastics were visually observed by a light binocular microscope, and then polymer types were detected with FTIR. Mean microplastic abundance ranged from 4.38 to 10 microplastics/GIT with an average occurrence rate of 100%. Red, transparent, black, and blue fibres (37.50 to 81.82%) were the most dominant MP colour. Most (88.35%) extracted microplastics were 100 to 1500 µm. Polypropylene and polyethylene were the most abundant polymers, accounting for 36.45 to 53.51% and 32.56 to 47.18%, respectively. A risk assessment of microplastics using the polymer hazard index revealed that microplastic contamination in these fishes (PHI = 565.40 to 659.26) from Saint Martin's Island were classified in the “Danger” risk category.