Tributyltin oxide

Tributyltin oxide (TBTO) is an organotin compound chiefly used as a biocide (fungicide and molluscicide), especially a wood preservative. Its chemical formula is [ ( C 4 H 9 ) 3 Sn ] 2 O . It has the form of a colorless to pale yellow liquid that is only slightly soluble in water (20 ppm) but highly soluble in organic solvents. It is a potent skin irritant.

Tributyltin compounds had been used as marine anti-biofouling agents. Concerns over toxicity of these compounds have led to a worldwide ban by the International Maritime Organization. It is now considered a severe marine pollutant and a Substance of Very High Concern by the EU.