The survey here described was carried out by Department of Marine ecology and founded by the Swedish Environmental Protection Agency in 2003, as a part of the monitoring process established by the OSPAR program in 1987 to monitor certain marine regions for TBT contamination. The present survey has focused mainly on point sources as recommended in OSPAR guidelines.

Nassarius reticulatus were collected from two harbours (Brofjorden and Göteborg harbour), were tributyltin (TBT) contamination was suspected, and three bays that served as reference sites (Burholmarna, Kalvhagefjorden and Malö hamn). Observations of imposex and analyses of tissue samples were used to assess the degree of TBT contamination. Results show that no location is unaffected and effects were found in areas expected to be free from imposex.