Concentration and health risk assessment of selected heavy metals in the tissue of frozen Atlantic herring (Clupea harengus Linnaeus, 1758)

Heavy metal contamination is a prominent issue which poses threats to aquatic ecosystems due to its toxicity, long half-life, resistance to degradation, bioaccumulation potential and resultant deleterious effects on human health. This study assessed the concentration of heavy metals in fish tissues and its attendant health risk to consumers. Lead (Pb), Cadmium (Cd), Chromium (Cr), Arsenic (As) and Mercury (Hg) concentration in the gills, muscles and liver of frozen Atlantic herring (Clupea harengus) were analyzed. Total Hazard Quotient (THQ), Daily Intake of Metals (DIM), Hazard Indices (HI) and Target Cancer Risk (TCR) in relation to consumer health risk and safety was also determined. The concentrations of the selected heavy metals in the digested samples were analyzed using Atomic Absorption Spectrophotometer (AAS) and Analysis of Variance (ANOVA) followed by the post-hoc test which established significance level at p < 0.05. Lead recorded highest mean value range of 0.79±0.00-1.18±0.12mg/kg in fish muscles across the three months of study and this was followed by Cadmium (Cd), Chromium (Cr), Arsenic (As). The least was Mercury (0.00±0.00-0.03±0.00mg/kg) with no significant difference (p>0.05). Pb and Cr levels exceeded recommended limits while Cd and As levels were below the Maximum Residue Level. The health risk assessment indices obtained were below the threshold, indicating consumption of muscle of imported frozen Atlantic herring in this study is safe and non-hazardous. However, due to the non-degradable nature and tendency of heavy metals to accumulate in tissues, regular monitoring is recommended.