Bioaccumulation and Human Health Risk Assessment of Multi-Metal Pollution in Selected Fishes from River Niger in Lokoja, Kogi State, Nigeria

Abstract

River Niger in Lokoja is a major freshwater resource supporting fisheries and domestic use, yet increasing anthropogenic pressures raise concerns about heavy-metal contamination. This study aimed to assess multi-metal pollution, bioaccumulation, and human health risks associated with consuming three commonly eaten fish species from River Niger. Water, sediment, and biological samples of Clarias gariepinus, Tilapia zilli, and Alestes baremoze were systematically collected during the dry season and analyzed for Pb, Cd, Hg, As, Cr, Ni, Cu, and Zn using Flame Atomic Absorption Spectrophotometer (FAAS) and hydride generation–atomic absorption spectrophotometry (HG–AAS). Data were evaluated with ANOVA and Tukey HSD at p < 0.05. Results showed that all water metals exceeded WHO/FAO (2017) limits, while sediments exhibited high enrichment of Zn, Pb, Cu, and Cr. Heavy-metal concentrations were highest in C. gariepinus, followed by T. zilli and A. baremoze, with Zn showing the strongest bioaccumulation. Estimated Daily Intake (EDI) values were consistently higher in children, and several Target Hazard Quotients (THQ) exceeded 1, resulting in Hazard Index (HI) values > 1 for all species, indicating potential non-carcinogenic health risks. This study has shown that consumption of fish from the River Niger may pose long-term health concerns, especially for children. Strengthened pollution control, routine environmental monitoring, and community-based risk-reduction strategies are recommended.