Tributyltin contamination in two estuaries and adjacent ocean coasts: Puget sound, Washington, and Narragansett Bay, Rhode Island (USA)

Concentrations of butyltins in the tissues of gastropods and measures of imposex in Nucella spp. and intersex in L. littorea were used to assess the levels of TBT contamination in two estuaries, Puget Sound and Narragansett Bay, both of which are subject to high shipping activity. Concentrations of butyltins in gastropods collected from both areas were low, although higher than those in adjacent coastal waters of open Pacific or Atlantic Ocean sites. Commercial harbours and dry docks were still hot-spots of contamination, but serious impacts were localised to within a few kilometres of the sources. Marinas were formerly highly polluted, but levels of contamination are now low, indicating that regulations prohibiting the use of TBT-based antifoulants on vessels <25m in length have been effective in reducing environmental levels of these compounds.