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(M/EH072) Zinc pyrithione - an environmentally sound alternative to organotin antifoulants? Doose, Caren1, Ranke, Johannes1, Jastorff, Bernd1, 1 ABSTRACT- Pyrithione based biocides are known since about 50 years and are widely used as cosmetic or industrial preservatives. The most common derivatives are the sodium salt (NaPT) and the zinc complex (ZnPT2). ZnPT2 is used since three decades as an effective antidandruff agent. Its broad spectrum of effectiveness and high activity against marine organisms causing biofouling lead to its use as an antifouling agent in the shipping industry. Recently early life stage tests resulted in significant teratogenic effects of ZnPT2 in fish (zebra fish and Japanese Medaka) at concentrations of 10 Key words: pyrithione, antifouling, speciation, environmental fate |
g/L. Due to the ban of organotin compounds the use of ZnPT2 as an antifouling biocide is expected to increase considerably. In the available publications little consideration has been devoted to the possible biochemically effective species apart from PT and PT- as there are the 1 : 1 and the 1 : 2 complex of e.g., Zn2+, Fe2+, Cu+ and Cu2+, respectively. Similarly, concerning the environmental fate important questions remain unanswered, for example degradation of ZnPT2 at temperatures below 15°C and environmental significance of transchelation of ZnPT2 to copper pyrithione (CuPT2), which exhibits a higher formation constant. We suspect that the persistence of CuPT2 in sea water and/or sediments is higher than the persistence of free PT or ZnPT2, and that CuPT2, which is also a highly effective biocide, is playing an essential role in fate and effects of pyrithiones. Here we report our results regarding chemical speciation of pyrithione complexes and degradation at low temperature.