Bioaccumulation of Pb was determined in Chlamys varia and Pecten maximus exposed to (210)Pb via seawater, food and sediment. Both scallops readily concentrated dissolved Pb with whole-body 7-d concentration factors of 250+/-40 and 170+/-70, respectively. In both species, more than 70% of Pb taken up from seawater was strongly retained within tissues (biological half-life>1.5 month) whereas Pb ingested with phytoplankton was poorly assimilated (<20%). As P. maximus lives buried in the sediment, this exposure pathway was assessed and showed low bioaccumulation efficiency for sediment-bound Pb (transfer factor <0.015). Despite the poor transfer efficiency of Pb from food and sediment, the use of a global bioaccumulation model indicated that the particulate pathway (food and/or sediment) constituted the major bioaccumulation route of Pb in both scallops. Whatever the exposure pathway, the digestive gland and kidneys always played a major role in Pb accumulation. In scallop tissues, Pb was predominantly associated with the insoluble subcellular fraction, suggesting a low bioavailability of Pb for scallop consumers.