Antifoulants, tributyltin

In more recent years two new types of antifouling composition have been developed, using organometallic compounds as poisons. In one type, based chiefly on vinyl resin and organotin compounds (e.g. tributyltin fluoride), the poison and resin form a solid solution. As the poison dissolves from the surface of the film, more poison diffuses from deeper in the film to... 

Poller (498, 544) prepared a number of tributyl- and triphenyl-stan-nyl esters of sucrose hydrogenphthalate and succinate, and found that, as potential antifoulants, these were at least three times as effective against the marine alga, Enteromorpka, as bis(tributyltin) oxide, even though they contain almost one third the tin (see Table VIII). A new antifouling paint that also contains tributyltin compounds has recently been developed in Norway (545). 

A second, parallel approach, has been to incorporate the tributyltin toxicant into an elastomeric matrix to produce long-life, antifouling. 

Butyltin compounds, in contrast, are produced only anthropogenically. Besides the applications covered in this CICAD, there exist other applications of butyltin compounds that may represent a significant source of these substances in the environment. In particular, the use of tributyltin compounds in antifouling coatings represents a significant source of these substances in the marine and freshwater environments. Hence, many of the measured concentrations reported will relate predominantly to this use. 

The highest levels of monobutyltin and dibutyltin in water and sediment are thought to relate mainly to degradation of tributyltin from its use on boats as an antifouling paint. 

Tributyltin compounds used as antifouling agents on boats have had serious toxic effects upon many mollusks, including populations of oysters and dog whelks. Females of the latter species developed a condition known as imposex, which rendered them infertile and caused local extinction of the population in shallow coastal waters. Imposex provides the basis for a valuable biomarker assay. 

Gibbs, P.E., Pascoe, P.L., and Burt, G.R. (1988). Sex change in the female dog whelk, Nucella lapillus, induced by tributyltin from antifouling paints. Journal of the Marine Biological Association of the United Kingdom 68, 715-731. 

Butyl- and phenyltin compounds, particularly the trialkylated forms are very toxic to marine life. The antifouling paints, mainly tributyltin (TBT) but also triphenyltin (TPhT) caused and continue to cause substantial damage because of their slow biodegradation and their accumulation in the biota, notwithstanding a substantial reduction in application through multi-national regulation). 

Marine antifouling paints containing tributyltin oxide or tributyltin fluoride are widely used all over the world29. However, tributyltin from marine antifouling paints has been shown to have a major impact on the oyster industry in Australia and in France. Concern for these effects has now led to the banning in many countries of the use of tributyltin-based antifouling paints on pleasure boats35. 

Organotin levels of the sediments, especially in tributyltin, are found to be very high compared with those of waters. It has been shown that Bu3Sn+, like other organometallics, is adsorbed rapidly by marine and other sediments. The sediment therefore represents a sink for Bu3Sn+ leached from the antifouling coating of boats. 

Bis(tributyltin)oxide in antifouling paint was found to change to tributyltin chloride and an unknown organotin species by Allen and coworkers106. The organotin species appear to be held strongly within the paint film. In the case of triphenyltin chloride and triphenyltin acetate, evidence of dephenylation to form diphenyltin and monophenyltin compounds has been obtained. 

Recently, pollution by organotin compounds was extensive in the environment and its effects on human health are feared. Organotin compounds such as tributyltin and triphenyltin, which are widely used in antifouling paints for ships and fishing nets, are very toxic to aquatic organisms38. These compounds may be accumulated in various organisms through the food chain. 

Copper is the active agent in many antifouling paints applied to watercraft (Aaseth and Norseth 1986 Hall et al. 1988). The growing use of copper-based paints subsequent to the prohibition in 1982 of tributyltin-based paints (Hall et al. 1988) is associated with elevated copper concentrations in Pacific oysters (Crassostrea gigas) farmed in the Bay of Arcachon, France (Claisse and Alzieu 1993). 

Tributyltin antifouling paints were banned for use in tin-based paints in the U.K. in 1987. Field work on the River Crouch Estuary showed that sediments from areas most contaminated with TBT in 1987 contained 0.16 mg TBT/kg DW however, by 1992 this had declined to 0.02 mg TBT/kg DW. TBT declines were accompanied by increases in abundance and diversity of benthic fauna, especially bivalve molluscs and amphipod crustaceans (Rees et al. 1999 Waldock et al. 1999). 

Bryan, G.W., P.E. Gibbs, L.G. Hummerstone, and G.R. Burt. 1986. The decline of the gastropod Nucella lapillus around south-west England evidence for the effect of tributyltin from antifouling paints. Jour. Mar. Biol. Assoc. U.K. 66 611-640... 

Dixon, D.R. and H. Prosser. 1986. An investigation of the genotoxic effects of an organotin antifouling compound (bis (tributyltin) oxide) on the chromosomes of the edible mussel, Mytilus edulis. Aquat. Toxicol. 8 185-195. 

Gray, B.H., C.L. Gaworski, J. Horton, C.D. Flemming, and L.H. Lee. 1985. Comparative dermal irritation by tributyltin and organotin-containing antifouling paints. Jour. Toxicol. Cutan. Ocul. Toxicol. 4 105-116. 

U ren, S.C. 1983. Acute toxicity of bis(tributyltin)oxide to a marine copepod. Mar. Pollut. Bull. 14 303-306. U.S. Environmental Protection Agency (USEPA). 1986. Initiation of a special review of certain pesticide products containing tributyltins used as antifoulants availability of support document. Federal Register 51(5) 778-779. 

U.S. Environmental Protection Agency (USEPA). 1987. Tributyltin. Technical support document. Position document 2/3. Mimeo. 152 pp. Avail, from U.S. Environ. Protection Agency, Office of Pesticides Programs, Registration Division, Special Review Branch, 401 M Street S.W., Washington, D.C. 20460. U.S. Navy (USN). 1984. Environmental Assessment of Fleetwide Use of Organotin Antifouling Paint. U.S. 

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