Nutritional Quality and Toxicological Risk Assessment of Mediterranean Mussels (Mytilus galloprovincialis): A Seasonal Study on the Kefken Coast, Black Sea

This study evaluated the metal content, fatty acid composition, and health risks of Mediterranean mussels (Mytilus galloprovincialis) collected over 8 months from the Kefken coast. As a transition zone between the Black Sea and Marmara Sea, this site is critical for monitoring nutritional quality and regional pollutants. The mussels showed a highly favorable lipid profile, with polyunsaturated fatty acids (PUFA) comprising 38.03 55.36% of total fatty acids. Optimal Atherogenicity (0.32–0.65) and Thrombogenicity (0.17–0.34) indices indicated strong cardiovascular benefits, while positive Selenium Health Benefit Values (9.33–14.25) suggested partial protection against mercury. However, risk assessments revealed severe non-carcinogenic concerns. Trace metals varied seasonally; Arsenic (As) and Mercury (Hg) peaked at 2.17 and 0.38 mg/kg (May/July), while Cadmium (Cd) reached 0.56 mg/kg (October). The carcinogenic risk for As (3–5×10-5) remained within the acceptable USEPA range. Conversely, the corrected Target Hazard Quotients (THQ) for Cd (up to 3.928) and Hg (up to 2.442) significantly exceeded the safe threshold (>1) for adults and children. Furthermore, the Benefit-Risk Assessment (HQEFA) under EFSA (2012) guidelines demonstrated that achieving recommended EPA+DHA targets (250–500 mg/day for adults; 324 mg/day for children) poses severe risks. Meeting the minimum 250 mg/day adult intake yielded Cd HQEFA values of 1.15–2.86, escalating to 5.72 at 500 mg/day, while Hg HQEFA values reached 2.64 for children. In conclusion, despite the exceptional lipid quality fostered by transition zone dynamics, the cumulative heavy metal contamination observed specifically in the Kefken coast samples poses significant health hazards, severely restricting the safe, unrestricted inclusion of this local mussel population in heart-healthy diets.