Microplastic contamination in thirty commercially important fish species: Distribution, polymer composition, pollution indices, and human health risks.

This study investigated the occurrence, distribution, and polymer composition of MP in 30 commercially important fish species (N = 600 specimens) collected from three major landing centres along the Thoothukudi coast from December 2024 to May 2025. Employing hydrogen peroxide digestion and ATR-FTIR spectroscopy for particle identification. Extracted MPs were identified based on their molecular composition, with a library match of >80%. MP concentrations varied significantly among species (p < 0.05), with the highest accumulation in the gastrointestinal tract (3.67-8.75 particles/fish), followed by gills (1.93-4.27 particles/fish) and muscle tissue (1.2-3.6 particles/5 g wet weight). Carnivorous species exhibited significantly higher MP burdens than planktivorous species, with Epinephelus longispinis showing maximum gut contamination (8.75 ± 2.36 particles/fish). Among 1446 particles analyzed, polyethylene (37.47%) and polypropylene (27.20%) dominated polymer composition, with fibers comprising 85% of particle morphology. A human health risk assessment revealed that estimated daily intake values ranged from 0.047 to 0.159 particles/kg body weight/day. The pollution risk (PRI) and hazard index (PHI) of most analyzed fish species ranged from 335 to 668 and 265 to 302, indicating considerable to medium hazard risk. These findings demonstrate widespread MP contamination across trophic levels in Thoothukudi's marine ecosystem, highlighting urgent needs for targeted pollution mitigation strategies and continued monitoring of MP bioaccumulation in commercially harvested fish species to protect both ecosystem integrity and human food security.