Se–Hg balance and seasonal trends in metal(oid) accumulation in red mullet (Mullus barbatus) from the southeastern Black Sea: Implications for human health

This study investigates seasonal variations in metal(oid) concentrations in red mullets from the southeastern Black Sea and evaluates the related health risks from their consumption. Fifteen metal(oid)s were analyzed, and a comprehensive risk assessment was performed using various indices, including Se/Hg molar ratios, metal pollution index (MPI), estimated daily intake (EDI), estimated weekly intake (EWI), provisional tolerable weekly intake (PTWI), target hazard quotient (THQ), hazard index (HI), and carcinogenic risk index (CRI). Statistically significant seasonal differences (p < 0.05) were observed in the concentrations of most metal(oid)s. The Se/Hg molar ratios consistently exceeded the protective threshold of 1.0, while positive HBV_Se values indicated a favorable selenium status that could help mitigate mercury toxicity. MPI values remained below 2.0 across all seasons, suggesting low environmental contamination levels. The calculated EDI, EWI, THQ, and HI values for all metal(oid)s fell within established safety limits, indicating no significant noncarcinogenic health risk. However, CRI values for arsenic slightly exceeded the acceptable threshold during spring and winter, indicating a potential carcinogenic risk during these periods. Given its benthic feeding habits and widespread distribution, red mullet serves as a reliable bioindicator species for monitoring environmental metal(oid) contamination in coastal ecosystems. These results highlight the importance of seasonal monitoring in seafood safety assessments and the necessity for region-specific regulatory frameworks. Overall, red mullet from the southeastern Black Sea can be considered a safe and nutritionally beneficial dietary component, although periodic increases in arsenic concentrations require ongoing surveillance.