Exploration of Nephrotoxic Heavy Metal Contaminants in Edible Fish and Reservoir Sediments Linking with CKDu Prevalence of Sri Lanka

Abstract

Inland fish is one of the main protein sources of the regular diets of remote communities in Sri Lanka where the incidences of Chronic Kidney Disease of unknown etiology (CKDu) have significantly increased. Nevertheless, the presence of nephrotoxic heavy metals in reservoir sediments poses a potential threat to the local ecosystem, particularly impacting the aquatic food web and fish populations. To study the problem, concentrations of heavy metals (Cd, Pb, As, Cr, Cu, Zn, and Mn) in two common edible wild and commercial inland fish species and associated reservoir sediments were investigated in selected CKDu endemic and non-endemic areas in Sri Lanka. The concentrations of heavy metals were 1,000 times higher in sediments than in dorsal fish muscles. Based on SQGs, Sediment-bound As, Cu, Zn, and Cd contents which exceeded the Effect range-low and median levels, implicated the harmful biological impacts to the living organisms inhabiting the Ulhitiya reservoir in the CKDu hotspot, including fish. Significant strong correlations in Cd, Pb, and Zn between the reservoir sediments and dorsal muscles of E. suratensis and O. niloticus confirmed that presume. Calculated Hazard Indices (HIs) were higher in E. suratensis (wild species) than O. niloticus (commercial species) irrespective of the location, and nephrotoxic heavy metals, including Pb, Cd, and As in fish muscles, contributed about 80% to the HI. Whether the estimated Target hazard quotients (THQs) for fish consumption were very much less than the threshold of 1, a relative possibility of the occurrence of chronic kidney failure of CKDu can exist due to exposure to the nephrotoxic heavy metals such as Pb, Cd, and As via fish consumption in the selected CKDu prevalence area. While a pollution event into an inland reservoir is often transitory, the pollutants' effects may be long-lived due to their tendency to be absorbed in the sediments and then released into the food chain. Even though detected heavy metal contents have complied with acceptable limits for human consumption, long-term consumption as the main animal protein source can directly impact the prevalence of CKDu among the residents in CKDu endemic areas in Sri Lanka.