Mercury levels in feed and muscle of farmed tilapia

Background: Fish consumption is considered the most important source of contaminant exposure for humans beings, and farmed fish can be exposed to contaminants via feed supply. Methods: Total mercury concentrations (THg) were determined in the muscle, liver, and feed of farmed Nile tilapia (juveniles and adults) from four different fish farms in Brazil (net cages and intensive tanks systems), by a flow injection mercury system. Results: Mercury concentrations observed in fish muscle were markedly lower (13.5-30.5μgkg^-1) than the values recommended by ANVISA/MAPA for edible part of fish (500μgkg^-1), and in the liver the concentrations found were higher than in the muscle. Conclusions: These low levels of THg in farmed tilapia may be due to the low THg concentrations found in the analyzed fish feed, that ranged from 5.2 to 33.2μgkg^-1, below the limit of 100μgkg^-1 established by the European Commission.