Tributyltin compounds are a group of compounds containing the (C₄H₉)₃Sn moiety, such as tributyltin hydride

Tributyltin hydride

Tributyltin hydride is an organotin compound with the formula 3SnH. It is a colorless liquid that is soluble in organic solvents. The compound is used as a source of hydrogen atoms in organic synthesis.-Synthesis and characterization:...

 or tributyltin oxide

Tributyltin oxide

Tributyltin oxide , or bisoxide, is an organotin compound chiefly used as a biocide , especially a wood preservative. Its chemical formula is C24H54OSn2. It has the form of a thin, colorless to pale yellow liquid with melting point -45 °C, boiling point 180 °C, and slight water solubility...

. They are the main active ingredients in certain biocide

Biocide

A biocide is a chemical substance or microorganism which can deter, render harmless, or exert a controlling effect on any harmful organism by chemical or biological means. Biocides are commonly used in medicine, agriculture, forestry, and industry...

s used to control a broad spectrum of organisms. These compounds are being considered for inclusion in the Rotterdam Convention

Rotterdam Convention

The Rotterdam Convention on the Prior Informed Consent Procedure for Certain Hazardous Chemicals and Pesticides in International Trade, more commonly known simply as the ', is a multilateral treaty to promote shared responsibilities in relation to importation of hazardous chemicals...

  and have been banned by the International Maritime Organisation.

Uses

Uses include wood preservation

Wood preservation

All measures that are taken to ensure a long life of wood fall under the definition wood preservation . Apart from structural wood preservation measures, there are a number of different preservatives and processes that can extend the life of wood, timber, wood structures or engineered wood...

, antifouling pesticide

Pesticide

Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...

 in marine paint

Paint

Paint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...

s, antifungal

Antifungal

* Antifungal medication, a medication used to treat fungal infection s such as athlete's foot , ringworm, candidiasis, etc.* Antifungal protein, a protein family* an adjective referring to a fungicide compound...

 action in textiles and industrial water systems, such as cooling tower and refrigeration water systems, wood pulp and paper mill systems, and breweries. Tributyltin oxide

Tributyltin oxide

Tributyltin oxide , or bisoxide, is an organotin compound chiefly used as a biocide , especially a wood preservative. Its chemical formula is C24H54OSn2. It has the form of a thin, colorless to pale yellow liquid with melting point -45 °C, boiling point 180 °C, and slight water solubility...

 is the most widely used compound in TBT–containing commercial products.

In the chemical laboratory, tributyltin hydride

Tributyltin hydride

Tributyltin hydride is an organotin compound with the formula 3SnH. It is a colorless liquid that is soluble in organic solvents. The compound is used as a source of hydrogen atoms in organic synthesis.-Synthesis and characterization:...

 generated by the action of lithium aluminium hydride

Lithium aluminium hydride

Lithium aluminium hydride, commonly abbreviated to LAH or known as LithAl, is an inorganic compound with the chemical formula LiAlH4. It was discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters,...

 on tributyltin chloride is used to replace halogen

Halogen

The halogens or halogen elements are a series of nonmetal elements from Group 17 IUPAC Style of the periodic table, comprising fluorine , chlorine , bromine , iodine , and astatine...

s in organic compounds

Organic chemistry

Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...

 for hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

.

Toxicity

TBT compounds are considered toxic chemicals which have negative effects on human and environment. Tributyltin compounds are moderately to highly persistent organic pollutant

Persistent organic pollutant

thumb|right|275px|State parties to the Stockholm Convention on Persistent Organic PollutantsPersistent organic pollutants are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes...

s that bioconcentrate up the marine predators' food net. One common example is leaching of TBT from marine paints into the aquatic environment, causing irreversible damage to the aquatic life. Tributyltin has also been linked to obesity in humans, as it triggers genes that cause the growth of fat cells.

TBT is harmful to some marine organisms, including the dog whelk

Dog Whelk

The dog whelk, dogwhelk, or Atlantic dogwinkle, scientific name Nucella lapillus, is a species of predatory sea snail, a carnivorous marine gastropod mollusc in the family Muricidae, the rock snails....

. TBT causes dog whelks to suffer from imposex

Imposex

Imposex is a descriptive term applied to some sea snails, marine gastropod molluscs which, under the toxic effects of pollutants, develop sex organs that are in contrast to their actual sex...

: females develop male sexual characteristics such as a penis. Trace amounts of just 2.4 nanograms of TBT per litre are needed to produce sexual changes in dog-whelks. This causes them to become infertile or even die. In severe cases males can develop egg sacs.

Tributyltin, dibutyltin and toxicity to marine mammals

Studies have shown that wild, dead sea otter

Sea Otter

The sea otter is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 14 and 45 kg , making them the heaviest members of the weasel family, but among the smallest marine mammals...

s (Enhydra lutris) and stranded bottlenose dolphin

Bottlenose Dolphin

Bottlenose dolphins, the genus Tursiops, are the most common and well-known members of the family Delphinidae, the family of oceanic dolphins. Recent molecular studies show the genus contains two species, the common bottlenose dolphin and the Indo-Pacific bottlenose dolphin , instead of one...

s can have extremely high levels of tributyltin in their livers. Both tributyltin and dibutyltin, a metabolite byproduct, cause immunosuppression, leading to secondary infections. This was supported by the finding that otters dying of infectious causes tend to have higher levels of tissue butyltins than those dying of trauma or other causes.

TBT has also been blamed by hearing experts for causing hearing loss in mammalian top predators such as toothed whale

Toothed whale

The toothed whales form a suborder of the cetaceans, including sperm whales, beaked whales, dolphins, and others. As the name suggests, the suborder is characterized by the presence of teeth rather than the baleen of other whales.-Anatomy:Toothed whales have a single blowhole on the top of the head...

s.

Tributyltin toxicity to marine invertebrates

TBT is extremely toxic to molluscs. In the case of bivalve larvae, the effective concentration (EC50) of TBT is 1000 times lower than that of any other toxic compound introduced into the marine environment. TBT also causes imposex

Imposex

Imposex is a descriptive term applied to some sea snails, marine gastropod molluscs which, under the toxic effects of pollutants, develop sex organs that are in contrast to their actual sex...

 in marine gastropods and is probably responsible for reductions in their populations in zones with important ship traffic.

Concerns over toxicity of these compounds have led to a worldwide ban by the International Maritime Organization

International Maritime Organization

The International Maritime Organization , formerly known as the Inter-Governmental Maritime Consultative Organization , was established in Geneva in 1948, and came into force ten years later, meeting for the first time in 1959...

. It is now considered a severe marine pollutant

Pollutant

A pollutant is a waste material that pollutes air, water or soil, and is the cause of pollution.Three factors determine the severity of a pollutant: its chemical nature, its concentration and its persistence. Some pollutants are biodegradable and therefore will not persist in the environment in the...

.

External links

• Newcastle University Biofouling Group
• "Ambient Aquatic Life Water Quality Criteria for Tributyltin (TBT)" United States Environmental Protection Agency
  United States Environmental Protection Agency
  The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
  
  , December 2003