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 im posex in Nucella spp. and intersex in L. littorea were used to assess the l evels of TBT contamination in two estuaries, Puget Sound and Narragansett B ay, 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 si tes. Commercial harbours and dry docks were still hot-spots of contaminatio n, but serious impacts were localised to within a few kilometres of the sou rces. Marinas were formerly highly polluted, but levels of contamination ar e now low, indicating that regulations prohibiting the use of TBT-based ant ifoulants on vessels <25m in length have been effective in reducing environ mental levels of these compounds.