Tissue-specific distribution and trophic transfer of PCBs in marine organisms from the Beibu Gulf, South China Sea: Probabilistic health risk assessment via Monte Carlo simulation

Despite global phase-out initiatives, legacy polychlorinated biphenyls (PCBs) remobilize in marine ecosystems as secondary emission sources, posing ecotoxicological and human health risks emerge through cross-trophic dietary exposure pathways. This study aimed to systematically examined the distribution, trophic transfer properties, and health risks of PCBs in six fish and eight invertebrate species from the Beibu Gulf in southern China, by stable isotope analysis, hierarchical cluster analysis, and Monte Carlo simulation. The Σ₂₄PCBs concentrations ranged from 0.17 to 1.98 ng/g wet weight (ww; 8.44-277 ng/g lipid weight). Tetra-CBs dominated the contaminant profiles, accounting for 32 % in Mugil cephalus and 53.2 % in invertebrates (excluding shrimp). Tissue-specific analysis revealed the highest PCB levels in the liver of Scoliodon laticaudus (13.2 ng/g ww) and the lowest in gills (0.41 ng/g ww). Trophic magnification factors (TMFs >1) identified biomagnification of five PCB congeners within the food web. Monte Carlo simulations revealed elevated non-carcinogenic risks in children compared to adults, despite estimated daily intake (EDI: 0.36-0.88 ng/kg/d) remaining below safety thresholds. This study reveals the bioaccumulation potential of PCBs in the food web of the Beibu Gulf and their human health implications. The findings underscore the need for region-specific monitoring frameworks integrating trophic dynamics and human exposure pathways, along with seafood consumption guidelines to mitigate the risks of legacy pollutants in coastal ecosystems.