Risk assessment of selected metallic pollutants in fish from Zuru dam, Kebbi State, Nigeria

This study investigates the concentration of metallic pollutants in fish samples from Zuru Dam and assesses the potential health risks associated with consuming these fish. Six fish samples, comprising three catfish and three tilapia, were collected from local fishermen. The concentration of metals, including iron (Fe), zinc (Zn), copper (Cu), chromium (Cr), cobalt (Co), lead (Pb), and potassium (K), was analyzed using the Atomic Absorption Spectrometric (AAS) technique. The results showed varying concentrations of Fe, Zn, and Cu, with Fe levels ranging from 7.85 ± 0.21 (CF2) to 128.5 ± 9.19 (TG3), Zn ranging from 8.75 ± 0.25 (CF2) to 42.321 ± 0.11 (CG1), and Cu found to be below detection limits (BDL) in several samples. The concentration of Cr, Co, Pb, and K also varied, with some samples showing detectable levels of these metals. Comparison with World Health Organization (WHO) tolerance limits revealed that Fe and Zn concentrations exceeded the acceptable limits, while Cu and K were well below their respective limits. Chromium and cobalt concentrations were within the WHO limits, except for a few samples, while Pb was only detected in TG1. The analysis showed significant differences (P < 0.05) in the concentrations of Cu, Cr, and Pb, indicating distinct pollution sources for these metals. Health risk assessment based on the Hazard Index (HI) indicated that adult consumers of certain fish samples, such as TG3, CG3, CG1, CG2, CF2, TG1, and TF1, may be at high risk of health problems due to the contamination, with HI values greater than 5. For children, HI values exceeding 1 in some samples suggested moderate health risks, particularly in TF2, TG1, CG1, and CG3. This study highlights the presence of significant heavy metal contamination in fish from Zuru Dam, posing health risks to consumers, particularly children and adults who consume high-risk samples. The findings underscore the need for regular monitoring of metal concentrations in the region and the implementation of pollution control measures. Public awareness programs should be initiated to inform local populations about the potential health risks associated with consuming contaminated fish, especially for vulnerable groups such as children. Further research is recommended to identify the specific sources of contamination and the long-term impacts on the aquatic ecosystem and human health.