Heavy Metal Contamination and Human Health Risk Assessment of Selected Seafoods from Coastal and Inland Communities of Rivers State, Nigeria

Abstract

This study assessed heavy metal contamination and associated human health risks in periwinkle, shrimp, and crab collected from coastal and inland communities of Rivers State, Nigeria, including Bonny, Ogoni, Eleme, and Omoku. Metal concentrations (Pb, Cd, Cr, Ni, Cu, Fe, Zn) were determined using standard analytical methods, and data were evaluated against WHO permissible limits. Results indicated that periwinkle and crab consistently exhibited higher metal burdens than shrimp, reflecting benthic and scavenging feeding habits and sediment interaction. Lead (Pb) concentrations ranged from 0.09 ± 0.01 mg/kg in shrimp from Bonny to 0.72 ± 0.03 mg/kg in periwinkle from Omoku, exceeding the WHO limit of 0.5 mg/kg in Eleme and Omoku. Cadmium (Cd) levels peaked at 0.081 ± 0.004 mg/kg in crab from Omoku, surpassing the permissible 0.05 mg/kg limit. Chromium (Cr) and nickel (Ni) were notably elevated in crabs from Eleme and Omoku, with maximum values of 4.72 ± 0.08 mg/kg and 7.94 ± 0.10 mg/kg, respectively, far exceeding WHO thresholds of 1.0 mg/kg. Essential metals (Cu, Fe, Zn) remained below toxic limits. Estimated Daily Intake (EDI) values were generally below oral reference doses, though localized hotspots were observed for Cd and Cr. Target Hazard Quotient (THQ) and Hazard Index (HI) values were <1 across all communities, indicating low non-carcinogenic risk, whereas Carcinogenic Risk (CR) and Total Carcinogenic Risk (TCR) values for Pb, Cr, and Ni in periwinkle and crab from Eleme and Omoku approached or slightly exceeded the acceptable lifetime risk range (10⁻⁶–10⁻⁴). The study demonstrates potential chronic health risks associated with long-term consumption of contaminated seafood, emphasizing the need for continuous environmental monitoring, industrial effluent control, and public health interventions to safeguard communities in the Niger Delta.