Survey of organotin compounds in the western Mediterranean using molluscs and fish as sentinel organisms

Tributyltin (TBT) and its degradation products, mono- (MBT) and dibutyltin (DBT) as well as triphenyltin (TPT) were determined in molluscs and fish collected along the Catalan coast (Western Mediterranean). Marine molluscs (mussels, clams and snails) were sampled from three harbors with different characteristics (small vs. large boats). Two fish species were studied (a) the grey mullet Liza aurata sampled in Barcelona harbor and (b) the red mullet Mullus barbatus sampled along the coast; different tissues (muscle, liver, gills and digestive tube) were analysed separately. The composition of butyltin compounds was different according to the organism and sampling point, but in general elevated concentrations of TBT were noticed in molluscs. The highest organotin residue levels (5.4 mu g/g d.w. as Sn) were detected in mussels from Masnou, a recreational marina, followed by those collected in Barcelona harbor (1.2 mu g/g d.w. as Sn). In contrast, no organotin compounds were detected in fish muscle and very low levels in the other organs, being TPT the major organotin in red mullet liver.