Dietary exposure and health risk assessment of metals in fish and shellfish from five markets in Southern Nigeria

Contamination of fish and shellfish with metals poses a significant public health concern, particularly in developing nations burdened with environmental pollution. This study evaluated the human health risks associated with the consumption of five fish and shellfish species; Tympanotonus fuscatus (periwinkle), Palaemon hastatus (crayfish), Ethmalosa fimbriata (Bonga fish), Clarias gariepinus (catfish), and Macrobrachium vollenhovenii (prawns) purchased from five states in Southern Nigeria: Akwa Ibom, Bayelsa, Ebonyi, Enugu and Rivers states. The samples were tested for four metals: cadmium (Cd), lead (Pb), mercury (Hg) and chromium (Cr). Concentrations of these metals were measured using inductively coupled plasma mass spectrometry (ICP-MS). Calculations of the estimated daily intake (EDI) of Pb, Cd, Hg and Cr for both adults and children were carried out using a mean ingestion rate of 24.7 and 1.86 g per day, respectively. The carcinogenic risk (CR) and non-carcinogenic risks were calculated for these metals. The results showed that the concentrations of Cd, Hg, and Cr in all samples were above the WHO/FAO permissible limits. While the African catfish and periwinkle samples had concentrations of Pb which were above the permissible limits, their EDI levels were below WHO/FAO recommendations. The findings indicated that while non-carcinogenic risks were generally low for each individual metal, the combined hazard index of the four metals showed that daily consumption of these five fish and shellfish species could lead to potential health risks in adults and children. Children may be at risk for possible health issues due to the accumulative characteristic of metals in human tissues. Exposure to Cd through the daily consumption of crayfish and bonga fish poses a notable carcinogenic risk, with cancer risk values near the upper threshold for acceptability in adults over time. The relatively high Cd levels in these species raises some concern, particularly for long-term consumption.