In vivo oral bioavailability of Pb sequestered in metal rich granules in bivalves

Abstract

The present study was designed to evaluate in vivo the oral bioavailability of lead (Pb) present in the marine bivalve Dosinia exoleta. This infaunal clam, despite inhabiting in clean areas, presents Pb concentrations that are over the 1.5 mg kg−1 wet weight limit for human consumption set by the European Commission. However, Pb is accumulated in this clam in the form of metal rich granules, and it has been shown to be unavailable for trophic transfer to a marine decapod, so it was hypothesised that it might be unavailable for human consumers as well. Twelve Sprague Dawley rats were fed during 14 days with a diet including control mussels (Mytilus galloprovincialis), D. exoleta, or mussels enriched in Pb to the same levels as those found in D. exoleta. Pb accumulation in different rat tissues (blood, bone, kidneys and liver) was analysed. It was observed that Pb assimilation from D. exoleta was about half of Pb assimilation from M. galloprovincialis, and absolute bioavailabilities were around 2% for M. galloprovincialis and 1% for D. exoleta. These results suggest that it might be possible to increase the limit for human consumption for this bivalve to 3 mg kg−1 wet weight without representing an increase in the risk for consumers.