Heavy metal contamination in commercial fish feed and cultured fish

Abstract

Fish is one of the major protein sources for Bangladeshis. It is a promising sector. One of the measures taken to encourage fish farming is the production of fish feeds. Fish feeds are usually in the form of granules or pellets which provide the nutrition in a stable and concentrated form, enabling the fish to feed efficiently and grow to their full potential. The feeds are combined with other ingredients such as vegetable, proteins, cereal grains, vitamins and minerals. Considering the importance of fish, the contamination of its feeds will greatly affect both the fish and the vulnerable population that depends on it as sources of proteins and as a food. In many ways these sources can be associated with anthropogenic heavy metal pollution. It is better to monitor any probable propagation of heavy metals into the food chain through the final feeds rather than the various raw materials for feeds. Three different commercial fish feeds Quality, Mega, Ruposhi and fish (Oreochromisniloticus) were collected from nine aquaculture farms ofMuktagachaUpazilla of Mymensingh district. Heavy metal (Cu, Fe, Pb, Cd, Na, Cr, Ni) concentration were determined by Atomic Absorption Spectrometer (AAS) in edible muscle from fish and in feed diets. The results show higher concentrations of Cd, Fe, Na and Pb in both fish feeds and fish muscles all of which exceeded the World Health Organization’s or other standard limits for food safety. Target hazard quotient (THQ) and target cancer risk (TR) were calculated to estimate the non-carcinogenic and carcinogenic health risks from fish muscles, respectively. The highest THQ value was estimated for Na (1.51) followed by Cd (1.45). This indicates that excessive consumption of Na and Cd over a long time period might cause non-carcinogenic effect as their THQ values were higher than the acceptable guideline value of 1 (USEPA 2011). In case of TR, although consumption of tilapia at current accumulation level is safe but continuous and excess consumption for a life time of more than 70 years has probability of TR.Precocious steps must be taken to avoid use of such health hazardous concentrations of heavy meals in fish feed and fish.