Dibutyltin (DBT) is used in the stabilization of the plastics polymerization process, and as a catalyst in polyvinylchloride (PVC) products. Approximately 70% of the total annual world production of non-pesticidal organotin compounds are used in the thermal and UV stabilization of PVC. Approximately 27000 tons of DBT and monobutltin (MBT) is used each year as stabilizers and catalysts. These organotin compounds make their way into the environment through PVC processing plants and PVC products maintained in water and water-handling systems. Also not used as a pesticide, DBT also finds its way into environmental systems as the primary degradation product of tributyltin (TBT), an active ingredient used as an antifoulant in marine paint.