The variation features of heavy metal contents in oyster samples from the coast of South China Sea and their safety assessment

The contents,distributions and variation features of heavy metal Cd,Cu,Pb,As,Hg and Zn in oyster samples collected from the coast of the South China Sea in 2009 were discussed,and the dietary exposure of heavy metals were calculated using point estimate.It showed that the contents of copper,zinc and cadmium in oyster samples were high and the contents of mercury,arsenic and lead were low,and their contents were 92.0,268,1.32,9.21,0.11 and 0.26 mg/kg(wet weight),respectively.The statistics results showed that the contents of cadmium,copper,lead,mercury,arsenic and zinc in oyster samples had obvious variation with sampling areas and cultivation seasons.Compared with the limit values of the safety requirements for non-environmental pollution aquatic product,the contents of copper,zinc,lead,mercury and arsenic in oyster samples were lower than the limit values,while the content of cadmium was higher than the limit value.The increased intake of bioavailable zinc reduced excessive cadmium absorption because oysters were rich in zinc with the low ratio of cadmium and zinc content.Therefore the cadmium in oyster samples was not harmful to health.The assessment results showed that the dietary exposures of heavy metals in oysters were lower than the recommended values of the Joint FAO/WHO Expert Committee on Food Additives(JECFA).