A structural equation model for assessing toxic effects of polycyclic aromatic hydrocarbons on scallop Chlamys farreri and the establishment of a novel integrated biomarker index.

Persistent organic pollutants (POP) occur in coastal areas worldwide and seriously affect marine ecosystems, especially aquatic organisms. Here, we assessed the bioaccumulation, biological effects, and health risks of polycyclic aromatic hydrocarbons (PAHs), one typical kind of global POPs, in the scallop Chlamys farreri from typical bays of the Yellow Sea and the Bohai Sea, China. Results revealed higher PAH bioaccumulation in scallops from Laizhou Bay and Jiaozhou Bay compared to Rushan Bay and Haizhou Bay. Structural equation modeling (SEM) was used to screen sensitive biomarkers, including aryl hydrocarbon receptor (AhR), ethoxyresorufin-O-deethylase (EROD), glutathione (GSH), DNA damage (DNAD), and acetylcholinesterase (AChE) in the digestive gland. Incremental lifetime cancer risk (ILCR) and margin of exposure (MOE) were calculated to assess dietary exposure risks, with ILCR suggesting a relatively low risk, while MOE indicated potential risks at two sites. A novel integrated biomarker index, i.e., integrated pollution index (IPI), was developed by merging integrated biomarker response (IBR) and multi-biomarker pollution index (MPI), providing a comprehensive assessment of the biological effects of PAHs on scallops. Spearman correlation analysis between IPI and PAHs content, ILCR, and MOE further verified its effectively. Collectively, this study will provide scientific foundation for monitoring marine POPs pollution risks and assessing the safety of seafood products.