Assessment of reproductive disorder (imposex) induced by tributyltins in marine gastropods.

Imposex is a genital disorder characterized by imposition of male sexual characteristics in female gastropods due to exposure to tributyltin (TBT). TBT is used as biocidal agent in antifouling paints, applied on the ship hulls and marine submerged structures such as fishing gears and buoys. In the present study bioassay experiment was carried out to determine imposex inductive and endocrine disruptive effect of TBT in two species of gastropods of genus Thais. In this experiment normal specimens of T. bufo and T. rudolphi were exposed to three different concentrations (100, 500 and 1000ngl) of TBTCl for four weeks in laboratory and at the end of experiment level of free testosterone and TBT body burden was estimated by radioimmunoassay and gas chromatograph coupled with a flame photometric detector respectively. In both tested species exposed to 500 and 1000ngl of TBT imposex stages developed, while in 100ng l and control groups showed no imposex condition. Elevation of free testosterone level in imposex females has also been observed. These observations indicate that the TBT act as potential imposex inducer and endocrine disruptor in the targeted gastropod species and these species can be used as sensitive biomonitoring tool for TBT contamination.