The effects of regulating the use of TBT-based antifouling paints on TBT contamination

There was severe TBT pollution in coastal waters in the mid-1980s, particularly in areas of high shipping and mariculture activity. Organotin concentrations were high in water samples sediments and tissues of marine molluscs. Responses, such as imposex in whelks and shell growth abnormalities in oysters, which can be caused by TBT, were also well-developed. They were associated with reproductive failure, and even local extinction of species, in the most severe cases. However, several governments have regulated the use of TBT-based antifouling paints, prohibiting their application to vessels <25 m in length. These regulations have been highly successful in reducing TBT pollution. Environmental concentrations of TBT have decreased, and there has been substantial recovery of populations of whelks and oysters. Serious TBT contamination is now restricted largely to ports and harbours, especially those with dry-docking facilities