Alkyltins in farmed fish and shellfish

A study to update dibutyltin (DBT) and tributyltin (TBT) residues in farmed fish and shellfish (Mytilus edulis) was carried out 4 years after the adopting of the restricting regulation of the antifouling uses of organotins in Italy. DBT and TBT were simultaneously extracted from farmed fish and shellfish (M. edulis) and from free living specimens, used as control, purchased from retail stores or fishermen in the province of Naples (Italy), and detected using a capillary gas chromatograph equipped with a flame photometric detector (GC-FPD). Dosable amounts of DBT were found in the 10% of the farmed fish analyzed, ranging from 1 to 26 micrograms kg-1 wet wt (mean 10 micrograms kg-1) and in the 23% of the free living fish at an average level of 2 micrograms kg-1 wet wt (range 1-4 micrograms kg-1 wet wt). TBT was detected in 85% of the farmed fish, in concentrations varying from 2 to 260 micrograms kg-1 wet wt (mean 28 micrograms kg-1 wet wt) and in 46% of the free living specimens (mean 39 micrograms kg-1 wet wt; range 1-93 micrograms kg-1). All the mussel samples analyzed were polluted by both DBT and TBT. In the farmed mussels the average amounts of DBT and TBT were, respectively, 4 and 2 micrograms kg-1 wet wt; in the free living they were 4 and 5 micrograms kg-1 wet wt, respectively. The results indicate that the DBT and TBT contamination is as highly diffuse in farmed as in free living fish and mussels on sale in retail markets in Naples province even if the levels of the contamination are meanly quite low.