FRA

Paints containing biocides prevent the adhesion of organisms to the hulls of ships, and are hazardous to aquatic ecosystems. I reviewed published literature reporting the behaviour, occurrence, and toxicity in aquatic environments of the organotin-free new antifouling biocides. Our analysis included the representative alternative new biocides; 2,4,5,6-tetrachloro-isophthalonitrile（chlorothalonil）, N’-dimethyl-N-phenylsulphamide（dichlofluanid）, 1-（3,4-dichlorophenyl）-3,3-dimethylurea（diuron）, 2-methylthio-4-t-butylamino-6-cyclopropylamino-s-triazine（Irgarol 1051）, 4,5-dichloro-2-（n-octyl）-4-isothiazoline（Sea Nine 211）, 2-（thiocyanomethylthio）benzothiazole（TCMTB）, bis-（1-hydroxy-2（1H）-pyridinethionate-O,S） zinc（zinc pyrithione, ZnPT）, zinc ethylene bis-（dithiocarbamate）（zineb）, pyridinetriphenylboron（PK）, and bis-（1-hydroxy-2（1H）-pyridinethionate-O,S） copper（copper pyrithione, CuPT）. These new biocides are classified as “toxic to very toxic” according to guidelines of the Organization for Economic Co-operation and Development, with toxicity values similar to those of TBT. The new biocides are decomposed by hydrolysis, photolysis, and biological activity and thus are less persistent in the environment than TBT, but low vapour pressure limits their evaporation. Because of medium octanol-water coefficient（Kow） and organic carbon partitioning coefficient（Koc） values, these new biocides, except for zineb, ZnPT, and CuPT, tend to be distributed in both seawater and sediments but have low bioaccumulation in aquatic organisms. Chlorothalonil, dichlofluanid, diuron, Irgarol 1051 and its degradation product, 2-methylthio-4-tert-butylamino-6-amino-s-triazine（M1）, and Sea Nine 211 have been found in natural waters, with higher concentrations in marinas and small harbours for fishing boats than in coastal waters, but insufficient data are available to assess contamination by these biocides. The reported concentrations of Irgarol 1051, M1, and Sea Nine 211 exceed their respective predicted no-effect concentration values, especially in marinas and fishery harbours, suggesting that these new biocides are already harming aquatic ecosystems in some areas. Further research is needed to assess the ecotoxicological risks of these biocides and to develop methods for estimation of their concentrations in ambient water.