Heavy Metal Accumulation and Health Risk Assessment in Coastal Seafood, Ondo State

Coastal seafood consumption provides a major source of dietary protein and micronutrients for communities along the Ondo State coastline, yet chronic exposure to heavy metal contamination in commercially harvested shellfish and crustaceans poses significant health risks that remain inadequately quantified. This study conducts a comprehensive heavy metal accumulation and probabilistic human health risk assessment for frequently consumed seafood species including Penaeus notialis (shrimp), Crassostrea gasar (oyster), and Callinectes amnicola (swimming crab) harvested from the Ilaje coastal zone, Ondo State, South West Nigeria. A total of 180 individual specimens are sampled quarterly from three landing sites over twelve months in 2023 to 2024. Muscle and hepatopancreatic tissue concentrations of cadmium, lead, arsenic, mercury, zinc, and copper are determined by inductively coupled plasma mass spectrometry following microwave acid digestion. Bioconcentration factors relative to ambient water and sediment concentrations characterise species-specific accumulation efficiencies. Monte Carlo simulation with 10,000 iterations is applied to probabilistically estimate chronic daily intake, hazard quotients, and incremental lifetime cancer risk for adult male, adult female, and child exposure scenarios, incorporating variability in consumption rates from dietary recall surveys conducted among 120 coastal households. Findings are expected to demonstrate that oysters exceed permissible cadmium limits and that children face the highest combined hazard quotient attributable to arsenic. Recommendations address targeted public health messaging and seafood consumption advisories. Keywords: heavy metals, seafood, health risk assessment, Monte Carlo simulation, Ondo State