International Trends in Regulatory Aspects

Fuel consumption of ships is highly dependent on frictional loss occurring between ship's hull and sea water. Fouling of the ship's hull by marine organisms including barnacles, algae and molluscs increases friction, resulting in an increase in fuel consumption and/or a decrease in ship's speed. A number of chemical compounds have been used to prevent those organisms attaching to hulls. A typically used antifouling system involves coating the ship's hull with paint containing substances preventing attachment of organisms. Organotin compounds, tributyltin (TBT) and triphenyltin (TPT) were found to be excellent in efficacy as anti-foulants and also less harmful to paint workers than traditional chemicals including mercury or arsenical compounds. Development of self-polishing organotin co-polymer has produced extremely high performance and long life with an additional effect of keeping the surface smooth by the self-polishing mechanism.

In the 1970s most of the ships in the world bore organotin based antifouling paints on their hulls. The extent of the use of organotin compounds caused adverse effects on marine organisms particularly on molluscs. Legislative control of antifouling systems was introduced firstly in individual countries and since then there has been a trend towards worldwide regulation. After patient discussion for more than 10 years, an international treaty banning the use of organotin compounds in antifouling systems was adopted at the International Maritime Organization (IMO). In this chapter, the discussion at IMO is firstly reviewed and, subsequently, the treaty controls are described in detail. Finally, regulations for tin-free antifouling systems, currently being implemented in Europe and the United States, are briefly summarized.