The tributylétain (or TBT ) of formula (n-C4H9) 3Sn-X (where X is an anion, or an anion grouping of unit stress).

It is a powerful biocide, of the family of the products organostannic, poison for the plants and other organizations, used for this reason like pesticide and in the Antifouling S as of the Sixties but especially in the Seventies with the explosion of the Naval construction and the pleasure.
Il proved to be also a hormonal Leurre able with low dose of masculiniser the females of certain watery species, and one can fear similar effects on other species, of which the Man. Many a alternate is tested or sold, but rare are those which do not seem to pose problems of Environnement or of Santé.

It is one of the pollutants of appendix 2 of the strategy of OSPAR. Like lead, it was interdict in paintings which contained of them 20% at the end of the years 1980 and which in Europe do not contain any theoretically more

One drew the following industrial derivatives from them:

  • Oxide of tributylétain (TBTO),
  • Benzoate of tributylétain (TBTB),
  • Linoléate of tributylétain (TBTL),
  • Methacrylate of tributylétain (TBTM),
  • Fluoride of tributylétain (TBTF),
  • Chloride tributylétain (TBTCl),
  • Phosphate of tributylétain
  • Naphthenate of tributylétain (TBTN).

France was the first country to limit the use of the toxic TBT in the antifoulings (paintings known as “antisalissure” . to protect the exploitation from scallops, of the mould S and especially of the Oyster S which since 1975, appeared affected by this product on certain zones of the Atlantic Littoral. The bond with the TBT was really shown only in the Eighties, in particular in the Bassin of Arcachon.

Process of prohibition

In 1982, France with the first prohibits the use of the TBT on the boats, but only for the hulls of less than 25 m length. In November 1999, a resolution of the OMI (A.895) was proposed and adopt on October 5th, 2001, prohibiting paintings antifouling containing tin starting from January 1st, 2003. Their presence on the hull of a ship will be prohibited as of 2008.Ses molecules of degradation and metabolites (of which the tin which is not dégradable) will persist nevertheless a long time in the Sédiment S of the ports and on the sites of mud immersion of Dragage and with their downstream following the handing-over in suspension if necessary.

In 2005, according to the INERIS, of the tributylétain could still serve

- as Antifongique (anti-mould) in industry of paper, leather and the textile and in the coolant circuits;
- as Disinfecting and Biocide in the cooling towers and the powerplants, in hospital medium, etc
- as Repulsive for Rodent S;
- as Pest-destroying in the brewery
- as pest-destroying in masonry.
- as biocide certain products general publics (anti-allergenic pillows, aerosols for the feet,
- as biocide for textile fibers,
- as catalyst whose traces could remain in leather, the polyurethane, the polyacrylate)
- As element in medicinal products (RPA, 2003) or certain polyurethane foams. the Danish Agency of the Environment detected di TBT (atrates about the mg/kg) in products of great consumption out of PVC, which could be impurities of compounds organostannic (MBT, DBT) used as stabilizing additives of PVC

In France, in the basin Adour-Garonne, a specific increase (in space and time) in the rates of TBT (> 10 ng/l) was measured in water downstream from the purification plants.

Kinetics and behavior in the environment

It is soluble in sea water, in which it the dissolved one in the form of chloride or carbonate hydroxides. It is badly adsorbed on the suspended matter (5% max). It is degraded under the action of the light and certain microbes, but of many organizations time has to introduce it before it disappears from the environment.
En fresh water (channels, rivers, lakes.), it on the contrary is strongly adsorbed on suspended matter, from where contaminations improtantes of the Sédiment S up to 1.000 times more important (until the mg/kg) that in the water column (in µg/l).

Its fresh water half-life varies from 360 to 775 days in the sediments of surface, and 10 years even more in condition Anaérobie.

breakdown products

The tributylétain is degraded while releasing from the dibutylétain (DBT) and monobutylétain (MBT), also poisons, but less than is to it the TBT.

Toxicology

Ecotoxicology

Its toxicity for the Environment and certain organizations was the subject of concerns only in the middle of the years 1970. it was noted that a small marine snail, the female Pourpre of the Atlantic ( Nucella lapillus ) proved to be sensitive to negligible concentrations of TBT (a half Nano gram (ng) per liter, sufficient to reveal a penis in the female of this animal, which ends up blocking the oviduct, blocking the reproduction of the species, causing in a few years of the brutal reductions in population, even of the local extinctions. This phenomenon baptized “Imposexe” (for imposition of the male sexual physiological characteristics on the females of the same species) is one of the effects of pollutants known as disturbing endocriniens. The TBT is moreover little dégradable. And there remains extremely toxic hidden in the sediments from where he can be extracted by the animals digger, or suspended during the clearings out or in the turbulences caused by the propellers of ships, or at the time of operation of trawling. Important effects on demography of the populations of various organizations are observed as of 40 ng per gram of dry weight.

External bonds

  • Card INERIS (updated: May 10th, 2005)
  • Model of prediction of environmental contamination by the antifoulings
  • Research of alternative
  • Internet site of the American manufacturers of stabilizing to tin
More
  • Report/ratio WHO, Concise International Chemical Assessment Document 14 TRIBUTYLTIN OXIDE, 1999
  • 11èmes days of the medicine of the Sailors, organized with the Ministry for Ecology and Sustainable development.
  • Re-examined Medicina Maritima which produced several articles of which “toxicological Risks aboard ships” December 2004.

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