Microplastic contamination and biological alterations in Atlantic wild fish populations, and human health risks associated to fillet consumption

This study tested the hypothesis that long-term exposure to microplastics (MPs) is causing biological alterations in North Atlantic wild populations of Trisopterus luscus (pouting) and Merluccius merluccius (hake). It also estimated the human risk of MP intake (HRI) through fillet consumption, and combined the HRI and polymer health hazard in the Risk of Intake and Polymer Hazard Index (RIPHI). Fish (103) were analysed for MPs (gastrointestinal tract, gills, liver, brain, muscle), biomarkers (physical condition, neurotoxicity, energy production, oxidative stress and damage) and general stress (Integrated Biomarker Response - IBR). After particle analysis (Fourier Transform Infrared spectroscopy, Raman spectroscopy) and data correction for contamination, MPs accounted for 77 % of 311 particles. From 103 fish, 79 % contained MPs. The overall mean concentration ±SD was 0.09 ± 0.09 MP g^-1 (2.32 ± 2.35 MPs ind^-1) with no significant interspecific differences (p > 0.05). Among body sites, brain had the highest MP concentration (pouting: 0.6 MP g^-1; hake: 0.5 MP g^-1). Most abundant polymers were polyethylene (40 %), polypropylene (21 %) and polymethyl methacrylate (12 %). Fragments (<150 μm) predominated. MP profiles pointed to prey-predator transfer. Fish with MPs had higher stress levels (IBR, pouting: 0.317; hake: 0.200) than specimens without MPs (pouting: 0.0; hake: 0.062). Oxidative stress was the effect most clearly linked to MPs. Hake fillet poses lower HRI (e.g., 0.2 to 1.5 MPs day^-1) than pouting fillet (e.g., 0.4 to 3.0 MPs day^-1). RIPHI values showed the opposite trend (e.g., hake: 138 to 1038; pouting: 113 to 845), indicating medium to high risk to human consumers. Findings related long-term MPs exposure in the natural habitat with biological alterations in wild fish populations, highlight the importance of food diversification for a healthy alimentation, and stress the urgent need of reducing MPs pollution to promote ecosystem sustainability and global health.