Environmental Exposure and Bioaccumulation of Potentially Toxic Elements in Fishery Resources from the Romanian Black Sea and Implications for Seafood Safety

Potentially toxic elements (PTE) are persistent contaminants in coastal systems and may accumulate in marine organisms, with relevance for both environmental monitoring and seafood safety assessment. This study provides an exploratory cross-biota assessment of Cd, Cr, Cu, Ni, and Pb in fishery resources from the Romanian Black Sea in 2024. The dataset included 24 composite samples and 120 analyte-level observations across bivalves, gastropods, pelagic fish, and demersal fish. Tissue concentrations were integrated with regulatory maximum levels, bioconcentration factors (BCF), biota–sediment accumulation factors (BSAF), and adult dietary risk indices, including estimated daily intake (EDI), target hazard quotient (THQ), and total target hazard quotient (TTHQ). Within the limits of this single-year dataset, Cd and Pb concentrations were generally higher in bivalves than in fish and gastropods, whereas Cr showed higher values in several fish samples, particularly pelagic fish. Cd was the main element of concern, with regulatory exceedances occurring mainly in bivalves and fewer exceedances in pelagic fish, while Pb exceedance was isolated. BCF and BSAF supported the relevance of Cd as a priority element but were interpreted only as descriptive tissue–water and tissue–sediment ratios, not as evidence of specific uptake pathways. Low abiotic Cd concentrations may have inflated some ratio-based values, and Cr interpretation remains limited by the absence of Cr speciation and dissolved/particulate partitioning data. The adult dietary risk assessment did not indicate substantial non-carcinogenic concern, as all individual THQ values and cumulative TTHQ values remained below 1. Overall, the findings support continued PTE monitoring in the Romanian Black Sea, using sessile bivalves as indicators of local environmental contamination and including gastropods and representative pelagic and demersal fish species of ecological and fisheries relevance to capture contaminant patterns across benthic and mobile fishery resources. Future monitoring should improve species-level replication, integrate metal partitioning in abiotic matrices, and include additional contaminants of seafood safety relevance, particularly Hg and As.