Preliminary Identification of the Bioaccumulation of Microplastic Particles in Oreochromis niloticus (Tilapia) Sold at Polomolok Public Market

Microplastic pollution in freshwater systems poses emerging risks to food safety and human health. This study assessed the bioaccumulation of microplastics in O. niloticus (Tilapia) sold at the Polomolok Public Market, South Cotabato, Philippines. A descriptive comparative cross-sectional design was used, with thirty fish sampled from three market stalls. Microplastics were extracted from gastrointestinal tracts using potassium hydroxide digestion, followed by density separation and microscopic identification. Microplastics were detected in all samples, yielding a total of 2,237 particles. Polystyrene was the dominant type, followed by pellets and fragments, while fluorocarbon particles were not observed. Variations in microplastic abundance were noted across sampling locations, with Stall 3 consistently showing higher counts. Statistical analysis revealed a significant difference among stalls (Kruskal–Wallis test, p = 0.010), and pairwise comparisons confirmed a significant difference between Stall 1 and Stall 3. No statistically significant correlation was found between microplastic load and morphometric parameters, including body weight and gastrointestinal tract weight. These findings suggest that microplastic accumulation in O. niloticus is influenced more by environmental exposure than by fish size. The presence of microplastics in market-sold fish raises concerns for consumer exposure and highlights the need for improved waste management and continued monitoring.