The effects of short-term changes in environmental parameters on the release of biocides from antifouling coatings: Cuprous oxide and tributyltin

Current and forthcoming UK and European legislation requires environmental risk assessment of antifouling paints, For assessments to be carried out su ccessfully, the leaching rate of biocides from antifouling paints should be determined. Current methods for the measurement of biocide leach rate have been shown to be very susceptible to changes in parameters such as pH, sal inity and temperature. Using apparatus designed to simulate environmental c onditions the effect of short-term changes in salinity, pH, temperature, su spended particulate matter and simulated vessel speed on cuprous oxide and tributyltin (TBT) leaching from self-polishing antifouling paint was invest igated. No effect on copper leaching was observed over a wide range of envi ronmentally relevant conditions, whilst vessel speed was the only parameter found to influence TBT release rates significantly, It is suggested that t he decrease observed may be due to the formation of a boundary layer which slows down the release of TBT from the paint surface. The environmental aut henticity of this observation and its possible implications for the environ mental risk assessment of TBT are discussed. Copyright (C) 1999 Crown Copyr ight.