The use of antifouling products (boat hull coatings) to prevent biofouling (the attachment of marine organisms to surfaces) is problematic from a marine environmental perspective because the majority of active substances used in hull coatings dissolve in water and are also toxic to aquatic organisms other than biofoulers. Toxic coatings are used because biofouling causes problems for boat owners: it slows boats down and increases fuel consumption.
The majority of the toxins used end up in the Baltic Sea. The Baltic Sea is a sensitive ecosystem, and active substances used in antifouling products are harmful to the "key species" of the Baltic that play a major role in the success of other Baltic species. Because of the adverse effects of antifouling products, a limit value has been set on copper emissions from paints used on pleasure boats. It is totally prohibited to use antifouling coatings on boats that mainly sail inland waters.