Health risks associated with accumulation of heavy metals in fish of Keenjhar Lake, Pakistan

The Keenjhar Lake in the southern part of Pakistan is exposed to heavy metal contamination, mainly due to the lack of proper upstream industrial effluent treatment. In this study, accumulation of heavy metals in five frequently consumed fish species Cirrhinus mrigala (Morakhi), Labeo rohita (Kur’ro), Solea solea (Mundi), Sperata seenghala (Singharo), and Anguilla bengalensis (Baam) from Keenjhar Lake were investigated. A total of 30 fish samples were collected from fishermen at the lake. Fish tissues were digested using standard methods and analyzed for metals using an atomic absorption spectrophotometer (AAS). Heavy metal (Cu, Ni, Pb, total Cr, Cr(VI), and Cd) concentrations were detected both in fish muscles and liver. Among the five targeted species, Cirrhinus mrigala appeared to be the most bioaccumulative fish, with Cr (219.78) > Pb (34.20) > Cu (22.49) > Ni ((16.24) > Cr(VI) (15.25) > Cd (0.01). The target hazard quotient (THQ) and hazard index (HI) were calculated to assess human health risk. The concentration of metals showed a significant difference among fish muscles and liver in the three studied locations. The total HI for heavy metals were estimated to be less than 1, but the cancer risk (CR) for Pb and Cr(VI) exceeded acceptable limits for fish consumption. From the human health perspective, this study informs local populations, i.e., fishing communities and population consuming approximately 150 g/day of Keenjhar Lake fish regularly are chronically exposed to Pb and Cr(VI) contamination with (10ˉ4 to 10ˉ6) carcinogenic risks.