Heavy metal accumulation and health risk assessment of crayfish collected from cultivated and uncultivated ponds in the Middle Reach of Yangtze River

Abstract

Crayfish, an aquatic food consumed globally, has been reported to accumulate heavy metal. To assess the health risk to the crayfish-consuming population, we investigated heavy metals (Cu, Pb, Zn, Fe, Mn, Cd, Cr, Ba, and As) in crayfish tissues (exoskeleton, abdominal muscle, gills, and hepatopancreas) and sediments from uncultivated and cultivated ponds in the middle reach of the Yangtze River. The metals, except for As, were measured by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and As was measured by atomic fluorescence spectrometry. The distribution of heavy metals differed significantly among tissues and concentrations were generally highest in the hepatopancreas. The average concentrations of heavy metals were higher in crayfish from uncultivated ponds than in crayfish from cultivated ponds. Heavy metal concentrations in crayfish correlated positively with sediment concentrations in uncultivated ponds, indicating that heavy metals can accumulate in crayfish. However, this positive correlation between sediment concentration and crayfish concentration was not observed in cultivated ponds. Source identification, using correlation analysis, indicated that heavy metals in the sediments derive from transportation and agriculture. Based on correlations between heavy metal concentration and body weight, and data on metal distribution in organs, heavy metals accumulate in the hepatopancreas of crayfish in uncultivated ponds, but not in cultivated ponds. Heavy metal concentrations were somewhat higher in female crayfish than in male crayfish and the difference was significant for Fe and Pb. The target hazard quotient (THQ) was used to evaluate non-carcinogenic health risk, with THQ < 1 considered to be safe. All THQ values were < 1, except for Cu in the hepatopancreas (THQ = 1.38) of cultured crayfish and Pb (THQ = 1.01) and Cd (THQ = 1.69) in the hepatopancreas of wild crayfish. Thus, the health risk posed by consuming crayfish, particularly cultured crayfish is low. Our research was designed to protect food safety and the results indicate that the health risk posed by heavy metals in crayfish is low.