Assessment of metal, metalloid, and radionuclide bioaccessibility from mussels to human consumers, using centrifugation and simulated digestion methods coupled with radiotracer techniques.

The dietary bioaccessibility of seven elements ((241)Am, Cd, Co, Cs, Mn, Se, and Zn) in the Mediterranean mussels Mytilus galloprovincialis (Lamarck, 1819) was assessed for human consumers. In this respect, we assessed and compared the proportion of elements associated with the cellular cytosolic ("soluble") fraction vs. the bioaccessible fraction derived, respectively, from (1) the differential centrifugation method and (2) the simulated digestion method. Comparisons were carried out on both raw and cooked mussels. Results showed that (1) the centrifugation method systematically underestimated (up to a factor 4) element bioaccessibility in raw mussels compared with the in vitro digestion method (e.g., 10% vs. 42% for (241)Am), and (2) the cooking process (5min at 200 degrees C) leads to concentrating the elements in mussel tissues (e.g., by a factor 2 for Zn) and reducing their bioaccessibility. Overall, the simulated in vitro digestion method appears as a powerful tool for seafood safety assessment and cooking could contribute in reducing substantially the global trace element intake from mussel tissues (up to 65% for Cd and Cs).

Bioaccessibility of essential and non-essential metals in commercial shellfish from Western Europe and Asia.

Maximum acceptable concentrations of metals in food - based on total concentrations - have been established in many countries. To improve risk assessment, it would be better to take into account bioaccessible concentrations. A total of seven species of molluscs from France, UK and Hong Kong was examined in this study including clams, mussels, oysters, scallops and gastropods. The species which have total metal concentrations higher than the most severe food security limits are mainly oysters (all of the three studied species), the gastropod Buccinum undatum for cadmium and zinc, and scallops for cadmium. The lowest bioaccessibility (in % extractability with gut juices) was observed for silver (median for all of the species: 14%), it was moderate for lead (median: 33%) and higher for cadmium, zinc and copper (medians were respectively 54%, 65%, and 70%). In most cases, bioaccessible concentrations remained higher than the safety limits, except for cadmium in scallops and zinc in B. undatum. The influence of feeding habit (masticated or swallowed, addition of vinegar or lemon) on metal bioaccessibility in oysters is limited. On the contrary, cooking the gastropods decreased the bioaccessibility of metals, except silver.