Concentrations of organotin compounds and imposex in the gastropod Hexaplex trunculus from the Lagoon of Venice

In four stations located close to the channels connecting the Lagoon of Venice with the Adriatic Sea (two inside the lagoon and two outside it), individuals of Hexaplex trunculus were collected in order to assess their contamination. Concentrations of some organotin compounds, i.e. tributyltin and triphenyltin with their di- and mono- substituted metabolites, were measured and endocrine disruption such as imposex (superimposition of male sexual characteristics on females of gonochoristic gastropods) was observed. Vas deferens sequence indexes (VDSI) of 4.1–4.9 were found in organisms from stations inside the lagoon, and 3.6–4.2 in the sea stations. Organotin derivatives were measured in both the visceral coil and the rest of the soft body of the organisms. Total concentrations of butyltin compounds ranged from 102F17 to 432F27 ng Sn g 1 d.w. in the visceral coil, and from 96F24 to 297F107 ng Sn g 1 d.w. in the rest of the soft body. Phenyltins were found at far lower concentrations, ranging from 8F1 to 41F3 ng Sn g 1 d.w. (visceral coil) and from 0.25 to 32F22 ng Sn g 1 d.w. (rest of soft body). The degree of imposex in female gastropods, evaluated from VDSI and penis lengths, was related to organotin contents in the soft body. In particular, female penis lengths were significantly correlated (r = 0.917 and r = 0.982, P < 0.05) to tributyltin (TBT) contents and the sum of organotin compounds in organisms.