Health risk assessment of heavy metals in freshwater fish in the central and eastern North China

The distribution and potential health risks of eight heavy metals (Copper (Cu), Chromium (Cr), Zinc (Zn), Lead (Pb), Arsenic (As), Cadmium (Cd), Manganese (Mn), Nickel (Ni)) in 16 freshwater systems from central and eastern North China, were investigated. The fish were divided as wild fish, which grew naturally without artificially feeding, and farmed fish. The total concentrations of the eight heavy metals ranged from 82.9 to 226 mu g/L in the surface water samples and 3.32-27.6 mg/kg dw in the fish samples. There was no significant difference in the heavy metal concentrations between natural and farmed water systems. The concentrations of toxic metals, including Pb, As, Cd, Cr, are similar in all kinds of fish. However, the essential metals (Zn, Cu, Mn, Ni) in crucian carp (15.9 mg/kg) was much higher than other kinds of fish. Comparing the wild and farmed fish, the average concentrations of each heavy metal in wild crucian carp, bighead carp, grass carp were higher than those in farmed fish. The average log BCFs (bioconcentration factor) of Zn, Cr and Cu were the highest (2.14, 2.04, 2.00 L/kg) while that of Cd (0.65 L/kg) was the lowest. The non-carcinogenic and carcinogenic health risks to adults and children resulting from consuming the fish were assessed based on the target hazard quotients (THQ). The results indicated that the non-carcinogenic health risk to humans by consuming fish products, no matter wild or farmed fish, was relatively low. The carcinogenic risk of inorganic As was 5.11 x 10(-6)-1.95 x 10(-4) for children and 2.71 x 10(-6)-1.04 x 10(-4) for adult, which are within the acceptable range. The results indicated that the concentrations of heavy metals in the freshwater fish in central and eastern North China were relatively low, and did not cause considerable human health risks.