Bioaccumulation of heavy metals in different fishes of Gangetic river system in Varanasi and its health risk assessment

Abstract

Abstract Heavy metal load is one of the factor causing deterioration of water quality of rivers and anthropogenic activities being the major cause. Present article is an attempt to evaluate the potential human health risks posed by four heavy metals (Pb, Mn, Cr and Cd). We have estimated the concentration of these heavy metal at different points of river Ganga as well as at confluence point of Ganga and Varuna rivers as follows: Pb 1.29 mg/L, Mn 1.325 mg/L, Cr 0.169 mg/L and Cd 0.161mg/L, which was above than the permissible limits stated by Environment protection agency EPA in drinking water. Randomly seven indigenous species of fishes were collected from the wild and were processed for checking the occurrence of these metals in the tissues such as Gills, Liver and Muscle. In all the seven selected fish species, degree of heavy metal concentration followed liver > gills > muscles. Highest accumulation of Pb was observed in Cyprinus carpio liver (8.86 µg/g) and lowest in Baikari muscles (0.07 µg/g). Total THQ value i.e. hazard index (HI) of metals was calculated for these fish species that are frequently consumed and the data showed HI values in following sequence: C.carpio > O. nilotus > C.punctatus > J.coitor > M.armatus > M.tengara > Baikari. Average HI value for C. carpio and O. nilotus was found above 1 which indicates that intake of heavy metals through these species may cause health hazard for human. Maximum HI was recorded in Carpio, which is highly consumed fish by human, hence may be harmful to them. These findings pose a threat to human population and hence needs regular monitoring of metals in fishes to prevent entry into food chain and its effect on the human beings.