A typical biocide-based paint erodes slowly over time, giving rise to a slow, but controlled release of biocides in the water. One of those biocides is tributyltin (TBT). In the 1980’s TBT was the dominating biocide in antifouling paints on leisure boats as well as cargo vessels. However, TBT in the marine environment also produced very serious adverse effects on gastropods and molluscs, e.g., oysters, causing endocrine disruption and rendering non-target organisms sterile. In addition, TBT is persistent and accumulates in the food chain. In 1989 the EU prohibited the use of TBT on leisure boats, but new alarming results suggest that large amounts of TBT still is present in underlying paint layers on boat hulls and is scraped off and accumulated in the soil and sediment.
Current marine antifouling paints include heavy metal additives, e.g., copper and zinc. Copper has a longstanding tradition as a biocide in antifouling paints but copper is a well-known toxicant that can be harmful to most organisms including humans. Recently it was found that Cu-ions (copper) interfere with olfactory sense organs in crustaceans and fish at very low concentrations giving rise to sub-lethal effects. Thus copper may seriously affect behaviors in a range of organisms.