Plastic litter pollution across recreational and non-recreational beaches of Cox's Bazar, Bangladesh

The world's longest unbroken natural sandy sea beach at Cox's Bazar is under constant threat from plastic litter pollution. However, the nature and extent of this pollution remain poorly quantified. Therefore, this study aimed to investigate plastic pollution patterns on ten recreational and non-recreational beaches along the Cox's Bazar coastline during the post-monsoon and winter seasons. A total of 903 plastic items belonging to 28 categories were identified. Recreational beaches accounted for approximately 71% of plastic litter abundance, with significant seasonal increases during winter. PCA and PERMANOVA confirmed significant spatial differences in plastic litter patterns between beach-use categories (F = 8.12, R2 = 0.318, p = 0.001). Cigarette butts, polythene bags, and plastic packaging materials were the most abundant litter items, whereas plastic bottles and fishing nets contributed the highest proportion by weight. Probable polymer types were inferred based on visible characteristics, physical properties, common applications, and reported polymer composition of similar plastic products. Polypropylene was the dominant polymer, while non-recreational beaches showed a substantially higher proportion of polyamide associated with fishing gear. Source-based classification revealed that tourist- and household-related plastics dominated recreational beaches, whereas fishing-related debris dominated non-recreational beaches. Single-use plastics accounted for 69.56% of plastic litter, and all surveyed beaches were classified as extremely dirty according to the estimated Clean Coast Index (CCI). These findings demonstrate that plastic pollution along the Cox's Bazar coastline is driven by tourism- and fisheries-related activities. Thus, improved waste management at recreational beaches and strengthened fishing-gear management at non-recreational beaches are essential.