The Content Variation Characteristics and Risk Analysis for Cadmium, Copper, Lead and Zinc in Some Species of Shellfish

According to the survey data on the shellfish of Ruditapes Philippinarum, Perna viridis, Crassostrea rivularis, Crassostrea gigas and Meretrix meretrix collected from the coast along South China Sea in 2007 and 2009, the content characteristics and the seasonal variation of cadmium(Cd), copper(Cu), lead(Pb) and zinc(Zn) in the samples were discussed, and the risk caused by these trace heavy metals was analyzed using the method of point estimation. The results showed that the contents of Cd, Cu, Pb and Zn changed with the various species of shellfish with the highest contents(except Pb) in Crassostrea rivularis and the lowest contents(except Zn) in Meretrix meretrix. There existed some seasonal variation for the contents of Cd, Cu, Pb and Zn in the shellfish which was due to the changes of environmental factors such as temperature, salt and dissolved oxygen in the seawater. Comparing with the other sea area, the contents of Cd, Cu, Pb and Zn in the shellfish from the present survey fluctuated between the normal levels, which showed most of these trace metals were relatively stable and under the control value issued by the standard of Non-environmental food products-Safe limits for the hazardous chemicals in the aquatic products(except Cd and Cu in a small amount of samples). The risk analysis results showed that the Pb contents in all the shellfish products were in the safe ranges according to the recommended values of the Joint FAO/WHO Expert Committee on Food Additives(JECFA), and the Cd contents were also in the safe ranges except in the species of Crassostrea rivularis. Judged by the contents of the trace heavy metals, the quality of the shellfish products from the present survey was in the edible security level, and just was the same as the products sold in the city markets.