tributyltin compound

Tributyltin (TBT) is an umbrella term for a class of organotin compounds which contain the group, with a prominent example being tributyltin oxide. For 40 years TBT was used as a biocide in anti-fouling paint, commonly known as bottom paint, applied to the hulls of oceangoing vessels. Bottom paint improves ship performance and durability as it reduces the rate of biofouling, the growth of organisms on the ship's hull. The TBT slowly leaches out into the marine environment where it is highly toxic toward nontarget organisms. TBT toxicity can lead to biomagnification or bioaccumulation within such nontarget organisms like invertebrates, vertebrates, and a variety of mammals. TBT is also an obesogen. After it led to collapse of local populations of organisms, TBT was banned. Chemical properties TBT, or tributyltin, tributylstannyl or tributyl stannic hydride compounds are organotin compounds. They have three butyl groups covalently bonded to a tin(IV) atom. A general formula for these compounds is . The is typically a chloride , hydroxide , or a carboxylate , where R is an organyl group. TBT is also known to be an endocrine disrupting compound, which influences biological activities such as growth, reproduction and other physiological processes. TBT compounds have a low water solubility, a property that is ideal for antifouling agents. The toxicity of TBT prevents the growth of algae, barnacles, molluscs and other organisms on ships hulls. When introduced into a marine or aquatic environment, TBT adheres to bed sediments. TBT has a low Log Kow of 3.19 – 3.84 in distilled water and 3.54 for sea water, this makes TBT moderately hydrophobic. TBT compounds have a high fat solubility and tend to absorb more readily to organic matter in soils or sediment. The bioaccumulation of TBT in organisms such as molluscs, oysters and dolphins, have extreme effects on their reproductive systems, central nervous systems and endocrine systems. However, the adsorption of TBT to sediments is reversible and depends on pH level in the body of water. TBT has a half-life of one or two weeks in marine water. When it accumulates in sediments its half life is about 2 years. TBT often bonds to suspended material and sediments, where it can remain and be released for up to 30 years. Studies have shown that 95% of TBT can be released from the sediments back into the aquatic environment.