Tributyl tin (TBT) is a synthetic organic tin compound that is primarily used as an additive to paints. In this application, TBT acts as a biocide or compound that kills plants such as algae, fungus, mildew, and mold that grow in or on the surface of the coating. These antifouling paints, as they are called, are applied to the hulls of ships to prevent sea life (e.g., barnacles and algae) from attaching to the hull. Growth of organisms on the hulls of ships causes ships to slow down and increases fuel consumption due to increased drag. Ships that are covered with these organisms can also transport non-native, or invasive, species around the world, which can disrupt an ecosystem and cause reductions in biological diversity. TBT is also used in lumber preservatives as an industrial biocide.

TBT-based paints were introduced more than 40 years ago. The first...