Assessment of the concentration, enzymatic activity, and health risks of heavy metals in Tilapia and Pangasius raised for human consumption

Abstract

Heavy metal contamination of fish is a global safety concern for the consumers. Atomic absorption spectrometry (AAS) was used to measure the concentration of three HMs (As, Pb, and Cr) in two commercially farmed fish species that are widely consumed: Oreochromis niloticus (tilapia) and Pangasianodon hypophthalmus (pangasius). This investigation was done to determine whether there was any potential health risk. The concentration of the studied heavy metals was within standard acceptable limits. As, Cr, and Pb had respective mean concentrations of 0.037 ± 0.023 mg/kg, 0.005 ± 0.002 mg/kg and 0.029 ± 0.015 mg/kg in the case of tilapia; and 0.049 ± 0.017 mg/kg, 0.007 ± 0.005 mg/kg and 0.024 ± 0.009 mg/kg, respectively, in the case of pangasius. Hierarchical clustering revealed that As may come through seepage and groundwater, while Cr and Pb are the products of contaminated feeds. ALP and ATPase activity varied significantly amongst the fishes' various organs. However, multiple regression analysis revealed that the current concentration of HMs in tilapia and pangasius was insufficient to predict enzymatic activity except for ALP in pangasius gill. The results of calculations for estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI), and carcinogenic risk (CR) indices made it abundantly evident that eating the fish under study posed no significant harm to the consumers' health. In conclusion, the contamination level of farmed tilapia and pangasius sold in the study area was within the permissible limit, however regular monitoring is needed to assure safe production.