Continuing Issues of Contamination by Organotins in the Marine Environment After Domestic and International Legislation

Abstract

Organotin compounds, which are used for painting on bottoms of ship’s hull, have high residual property in the environment, and examples of their detection in the environment have been reported even after the introduction of international regulations on their use. To better understand the residual concentrations of organotins in marine environments, studies have been conducted on regional and small-scale fishing harbors, rather than in areas with integrated, large-scale commercial harbors and dockyards and areas where industrial facilities unrelated to the fishing industry exist. This approach of using small fishing harbors has advantages because there are many sites available for analysis, and the analytical noise is low. It is found that the organotin compound concentrations in sediments of fishing harbors with repainting facilities are clearly higher than those of harbors without such facilities. The organotin contamination depends on the presence of the repainting facilities and not on the scale of the fishing harbor. It is proposed that paint flakes produced during the repainting of hull bottoms are discharged into the sea, and these paint flakes are a high concentration source of contamination. Since the difference in organotin values between harbors with and without repainting facilities is less than ten times at the median values, it is considered that organotin compounds are released intermittently into the environment during periods that a ship is in harbor and that the quantities of organotins in the environment are not as low as expected.