Assessment of Heavy Metal Contamination in Water, Soils, and Fish Tissues from Barandu River, Buner, Pakistan:...

Nowadays, rivers are subjected to hazardous metal pollution because of human activities which badly affect aquatic ecosystems and human health. This study investigates the bioaccumulation and potential health risks of heavy metal contaminants (Cu, Fe, Zn, Pb, Ni, Mn, Cd, Cr, and Co) in the water, soil, and tissues of Schizothorax plagiostomus from the Barandu River, with the aim of evaluating their safety for human consumption. The samples (fish, water and soil) were obtained from three different sites i.e., upstream (US), industrial (IS), and downstream (DS) and analyzed using atomic absorption spectrometer. Our analysis displayed significant Bioaccumulation of heavy metals in body tissues (Liver > Gills > Muscles) with levels exceeding the permissible limits established by the WHO, with except for Fe, Cu, Zn, Ni, and Cd. Furthermore, this study found elevated levels of Cu, Fe, Pb, Ni, Mn, Cd, Cr, and Co in water samples, while only Cd exceeded the standards in sediment, according to guidelines of WHO and the USEPA. Metal levels were significantly elevated (P < 0.05) at IS relative to the other two sites, and frequently, levels at DS were significantly higher (P < 0.05) than those at US. The estimated daily intake (EDI) of most targeted metals in S. plagiostomus tissues from US and DS sites was found to be within the permissible maximum tolerable daily intake (MTDI), indicating no significant health risks for the local population. However, at the IS, the EDI values for Mn, Cr, and Co surpass the MTDI, highlighting potential health risks correlated with the consumption of fish from this area. The Target hazard quotient (THQ) and Hazard index (HI) values for all the metals in fish organs were < 1 indicating that indirect intake of metals by consuming fish will not result in potential health hazard in humans. However, in the three Sites, Ni, Cd, and Cr exhibited a carcinogenic risk surpassing the permissible limit (< 1 × 10 - 4), signifying high cancer risk linked with S. plagiostomus consumption. Additionally, the PCA analysis indicates a positive correlation between the level of heavy metals in fish organs and water. The results obtained indicated that the discharge of industrial effluents led to a higher accumulation of heavy metals in fish tissues at IS when compared to US and DS. It is essential that all these industries either relocate from the bank of the River Barandu or ensure proper treatment of their effluents before discharging them into the river, to safeguard the biota of River Barandu from contamination resulting from these marble industries.