Organotins are chemical compounds that are organic derivatives of tin. A major source of organotins in the marine environment is the antifouling paints applied on ship hulls. Organotin compounds (chemically, they are characterized by the presence of at least one covalent carbon-tin bond) have been used as biocides in antifouling paints applied on hulls of ships and boats and, in general, on surfaces in prolonged contact with seawater to control the growth of fouling organisms.
As organotins are highly effective against most fouling organisms, their application resulted in enormous savings to the shipping industry. In fact, organotin-based, in particular tri-substituted organic compounds of tin (tributyltin, TBT), paints are described as the most effective antifouling paints ever devised for use on boat hulls. TBT has also been described as the most toxic substance ever introduced into the marine environment, especially because it is directly released into the aquatic environment. The high toxicity of TBT, together with its tendency to get accumulated in marine organisms, can adversely affect marine organisms, particularly mollusks and gastropods.