H. Ettajani, L. Pirastru oysters (Crassostrea gigas) exposed through sea water or via particulate matter (natural sediment, diatoms). The physico-chernical forms of silver stored in oysters suggests a moderate transfer to consumers. In the case of copper, transfer through feeding is not a negligible factor, through the associated risk is not doubt limited because of the key biological role played by this metal, and it therefore merits careful evaluation.