Current technology uses biocides in marine coatings lo protect the immersed part of ship hulls against fouling by marine organisms. Tributyltin (TBT) containing paints, although extremely effective as antifoulants, are highly toxic. TBT accumulates in bioorganisms because of" its fat soluble nature. Ingestion of TBT-contaminated seafood or water by humans can cause alterations in blood lipid levels, the endocrine system, liver and spleen, and has toxic effects on thymus.1 High levels of TBT in marine water has lead to increased mortality of oysters, mussels, clams and sea otters, and also a condition known as "imposex" in snails wherein female species began lo develop male characteristics. Because of its adverse environmental impacts, the use of TBT in antifouling paints is greatly restricted, and its ban by the International Maritime Organization will be effective in 2008.2 Copper-based coatings, which arc now widely used in its place, are also expected to face similar restrictions in the near future. Environmentally benign coatings that repel fouling organisms, or aid fouling release, are desirable alternatives to biocidal paints.
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