Anti-fouling systems have commonly been used to coat the bottoms of ships to prevent sea life such as barnacles attaching themselves to the hull, which might slow the ship and increase fuel consumption. These systems work by producing compounds which “leach” into the surrounding seawater.
Although anti-fouling systems may allow ships to make savings in time and fuel, studies have shown that the compounds remain in the water long after being released from the vessel, killing sea life which was never attached to the ship, harming the environment generally and possibly entering the food chain. One of the most effective and commonly used anti-fouling paints, tributyltin (TBT), has been proven to cause deformations in oysters and sex changes in whelks.
Consideration of the subject led to the International Convention on the Control of Harmful Anti-Fouling Systems on Ships, which was adopted by the IMO on 5 October 2001 and entered into force on 17 September 2008.