BIOACCUMULATION OF ORGANOTIN COMPOUNDS AND IMPOSEX OCCURRENCE IN A MARINE FOOD-CHAIN (EASTERN SCHELDT, THE NETHERLANDS)

During several seasons in 1995 common whelks (Buccinum undatum), musse ls (Mytilus edulis) and sediment were analysed for organotin compounds . For butyltin compounds, the order of concentrations in whole body ho mogenate of common whelks was DBT>MBT>TBT. TBT was usually just above the detection limit except for the samples of the neural ganglia (nerv e centre) taken in September. Here, only TBT could be detected, while the TBT/TPT ratio was >1. This could be important since the induction of imposer concerns the involvement of neuropeptides and/or steroid ho rmones. TPT concentrations in whole body homogenates of common whelks were 4-100 times higher than those of TBT. TPT clearly showed much hig her levels than its metabolites DPT and MPT. No structural differences in organotin contamination were found between the sexes, different st ages of imposer, or adult and juvenile common whelks. In mussels, TBT> DBT>MBT, but phenyltin ratios were comparable to those in the common w helk. Phenyltin whole body concentrations, however, were 5-10 fold bel ow those of B. undatum. Biomagnification of butyltin compounds is not expected, whereas comparison of phenyltin ratios between the two speci es suggests biomagnification. In total sediment samples organotins wer e usually below their detection limit. The percentage of adult and juv enile female B. undatum showing imposer was > 95% throughout the year.