Heavy metals pollution and health risk assessment in farmed scallops: Low level of Cd in coastal water could lead to high risk of seafood

Scallops are one of the most common bivalves, large-scale farmed in the coastal areas of China. Three species of scallops (Chlamys farreri, Argopecten irradians and Patinopecten yessoensis) from 10 samples sites along the Bohai Sea and the Yellow Sea were collected to investigate species-specific and tissues-specific bioaccumulation, spatial-temporal distribution and health risks for people. Cd must be paid attention since Cd concentrations in 96% of scallop samples exceeded standard with the highest Cd bioaccumulation potentials (BCF) >10,000 while those of the other metals were less than the corresponding limits except Zn with exceeding-limit percentage of 13%. The metal pollution index values showed that A. irradians could accumulate more metals than the other two species, and scallops in the Bohai Sea were polluted more seriously by heavy metals than in the Yellow Sea. The capacities of tissues in scallops to accumulate metals generally followed the order of digestive gland > gill > adductor muscle. However, Zn accumulated in gill was more than that in digestive gland and muscle. Adults and children would face the non-cancer risks because of the accumulation Cd in scallops based on health risk assessment. Cd was the major contributor of health risk to account for 85% of total hazard quotient and 48% of total cancer risk. Scallops could accumulate Cd rapidly from ambient environments to cause health risks according to the transplantation test. Moreover, the recommended maximum edible amounts of whole scallops were 127/63 g/week for adult/children on the basis of the provisional tolerance weekly intake. Humans are recommended to only consume adductor muscles for reducing health risks