Surveys of imposex in the dogwhelkNucella lapillussuggest that most parts of the north Atlantic are free of TBT contamination at biologically significant levels. Imposex was absent or poorly developed at the large majority of sites, including coasts adjacent to major shipping lanes passing through Pentland Firth, the Minches and North Channel. There were “hot-spots” of TBT pollution at ports and harbours along the northeast coast of England but, with the exception of the stretch of coast which includes the major ports of Hartlepool and Teesside, impacts were highly localised. The severity of imposex has declined dramatically during the past decade in those areas for which there are comparative data from earlier surveys. This can presumably be attributed to the success of regulations prohibiting the use of TBT-based antifoulants on vessels <25 m in length.