Lead, mercury and cadmium levels in edible marine molluscs and echinoderms from the Veneto Region (north-western Adriatic Sea – Italy)

In this study, heavy metal levels detected in molluscs produced in the Veneto Region (north-western Adriatic Sea) are presented and discussed. A descriptive analysis was conducted on data collected in the framework of official monitoring activities in shellfish production areas between 2007 and 2012. Concentrations of lead (Pb), mercury (Hg) and cadmium (Cd) in about 2000 samples of 17 different species of marine bivalve molluscs, echinoderms and gastropods were checked by means of atomic absorption spectrometry. Hg and Pb concentrations were always below the maximum levels set by the European legislation; 2.2% of the analysed samples exceeded the threshold level for Cd, 86.7% of witch belonging to purple dye murex (Bolinus brandaris). The highest mean levels of Hg and Cd were found in purple dye murex, with 0.10 mg kg−1 and 0.88 mg kg−1 respectively, while rayed trough shell (Mactra stultorum) and truncate donax (Donax trunculus) were the species with the highest mean value of Pb (0.25 mg kg−1). Species of major consumption showed mean values almost ten times lower than the limits set by the European legislation (Manila clam: Pb: 0.20 mg kg−1; Hg: 0.04 mg kg−1; Cd: 0.07 mg kg−1; Mediterranean mussel: Pb: 0.22 mg kg−1; Hg: 0.03 mg kg−1; Cd: 0.13 mg kg−1). A preliminary evaluation of the impact on human health of shellfish according to the detected levels indicates that the species of major consumption are safe for the average consumers, although a potential risk cannot be ruled out for vulnerable groups, such as women of childbearing potential and children, as well as for regular or high-level shellfish consumers, particularly those who frequently eat species such as murex.