Heavy Metal Bioaccumulation Pattern in Edible Tissues of Different Farmed Fishes of Mymensingh Area, Bangladesh and Health Risk Assessment

An experiment was conducted to study heavy metals bioaccumulation pattern in edible tissues of different farmed fishes and to assess human health risk through their dietary intake. Total 3 different species viz. grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix) and mrigel (Cirrhinus cirrhosis), and 3 dissimilar sizes of fish samples were collected from Muktagacha and Trishal area of Mymensingh district, Bangladesh during January 2018 and analysed for this study. Among the fish species, mean concentrations of Ca, Na and K were higher in mrigel; Mg and S contents were higher in silver carp and P content was higher in grass carp. As regards to heavy metals, mean concentrations of Pb (18.98 µg g-1), Ni (0.688 µg g-1) and Cu (15.197 µg g-1) were higher in mrigel; Cd (1.127 µg g-1), Cr (15.097 µg g-1) and Zn (36.023 µg g-1) contents were higher in grass carp, while contents of all metals were lower in silver carp. In context of size, both mineral nutrients and heavy metals bioaccumulation pattern in all species were higher in large size fishes. Similarly, metal pollution index values for all species of fish samples showed a sequence- large size> medium size> small size, which indicates that heavy metal bioaccumulation pattern was directly related to the size and age of fishes. The study results revealed that the daily intakes of Pb and Cd for all species and sizes of fish samples were higher than that of upper tolerable intake level. Target hazard quotients (THQ) values for Pb and Cr surpassed 1.0 for both male and female, which indicate that the exposed populations are in a level of concern interval. But in context of other heavy metals, these farmed fishes can assume as safe for human consumption.