Ecotoxicological and Human Health Risk Assessment of Heavy Metals in Sediment, Water, and Crayfish from Burutu, Delta State, Nigeria

Abstract

Aquatic environments are vulnerable to heavy metal contamination and have ecological and human health threats as pollutants accumulate in sediments and bio-accumulate in aquatic organisms, such as in riverine communities. The result of this study was to assess levels of heavy metals in sediment, water, and crayfish of five riverine communities in Burutu LGA and to elucidate the bioaccumulation potentials and the associated risks. It took samples that were collected in the wet and dry seasons and analysed for 21 heavy metals using the Atomic Absorption Spectrophotometry. Bioaccumulation factors (BAF), estimated daily intake (EDI), hazard quotient (HQ), carcinogenic risk (CR), and pollution indices (Igeo, CF, PLI) were risk assessed. The highest metal concentrations were recorded in sediments, with values of lead (Pb) at 89.43 mg kg−1, cadmium (Cd) at 6.72 mg kg−1, and nickel (Ni) in crayfish at 12.58 mg kg−1, which are above the regulatory limit. Cd Bioaccumulation Factor (BAF) > 5 bioaccumulates Cd strongly, and Pb Hazard Quotient (HQ) = 1.94 > safety threshold. Arsenic (As) CR (4.6 × 10⁻³) exceeded acceptable limits. Sediment contamination was considered moderate to high (PLI = 2.8 and Igeo for Cd = 3.2) as classified by pollution indices. The results do demonstrate very high levels of contamination, with significant consequences for human health and ecosystem stability. The findings of this study indicate the urgent need for pollution control, safe consumption practices, and strict regulations on heavy metal exposure in these communities.