Metal Levels in Crab Sentinel Species from the Mediterranean Sea: Safety and Toxicological Risk Assessment

The assessment of metal contamination in aquatic species represents an important tool to monitor the risk of exposure for these species in relation to marine pollution. Crabs are the sentinel species of the aquatic environment and are very sensitive to metal exposure because these inorganic contaminants can be easily absorbed into their exoskeleton and migrate into their inner tissues. The aim of this study was to assess the content of metals and metalloids (Hg, Pb, Cd, As, Cr, Mn and Ni) in species of warty crab (Eriphia verrucosa), brown crab (Cancer pagurus), and marbled crab (Pachygrapsus marmoratus), mainly distributed along the Mediterranean coastlines. The investigations, carried out on several parts of crabs (carapace and the related pulp, gills, claws and bronchial muscle) showed the presence of residual levels of metals and metalloids (Mn > Pb > Hg > As > Ni > Cr > Cd), correlated to the distribution of these elements in the marine environment and to the specific biological features of crabs. However, the values of Metal Pollution Index (MPI) suggested a low level of contamination of the marine ecosystem where these species were found, and the coefficient of correlation (K), a specific parameters of toxicological risk assessment, was indicative of crab health status. However, the residual levels of Hg, Pb and As above the MRL in all analyzed crab species underlined the importance of continuous monitoring studies on the safety of these sea-foods.