Suspect screening identification of emerging contaminants and their phase I and II metabolites in Mediterranean fish muscle: Implications for human exposure

Marine pollution in the Mediterranean has far-reaching consequences for the marine environment, wildlife and human health. Emerging contaminants (ECs) and their metabolites are increasingly recognized as critical but underreported contributors to human chemical exposure through seafood. This study aimed to comprehensively identify ECs and their phase I&II metabolites in Mediterranean edible fish. A suspect screening analysis platform was developed based on supramolecular solvent extraction and liquid chromatography-high-resolution mass spectrometry. Identification was guided by a suspect list of 11,000 entries (1702 parent compounds and 9298 metabolites in silico generated for Phase I&II pathways). Method limits of detection ranged from 0.50 to 2.61 ng·g⁻¹ . The platform was applied to 120 Mediterranean fish specimens, including two demersal (Mullus barbatus and Merluccius merluccius) and two pelagic (Sardina pilchardus and Trachurus trachurus) species. 81 compounds were detected, spanning plasticizers, flame retardants, pesticides, pharmaceuticals & illicit drugs, personal care products, and industrial & others. About half of these compounds (41) were metabolites, with their parent compounds mostly absent. Notably, 20 of them were methylated derivatives, a transformation not typically associated with detoxification in fish metabolism, highlighting the need to elucidate their biotic/abiotic origin. Detection patterns revealed some ecological contrasts: Sardina pilchardus and Trachurus trachurus accumulated the broadest chemical spectrum, while Mullus barbatus reflected sediment-derived contamination and Merluccius merluccius had the lowest chemical burden. This study provides one of the most comprehensive suspect screening of ECs and their metabolites in Mediterranean fish to date, revealing novel contamination pathways and critical implications for human exposure.