Tetracycline in antifouling paints

The banning of the use of tributyltin (TBT)-based antifouling paints on boats under 25 m in length, has lead to a search for replacement biocides. A recent yachting magazine article advocated the use of capsules of the antibiotic tetracycline to be added to cheap copper-based paints. The impact of such a paint on non-target bacteria, algae and oysters was investigated. Tetracycline was found to leach rapidly from painted surfaces and degrade quickly in seawater. The concentrations released were insufficient to cause any deleterious effects on marine organisms, including those responsible for fouling boat hulls.