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Environmental fate & pathways

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The ready biodegradability of gestonorone was studied in a CO2 evolution test according to OECD 305B. The test compound was incubated with a suspension of activated sludge from a municipal sewage treatment plant over a period of 28 days. A reference substance (sodium acetate) was used as positive control and a toxicity control with gestonorone and sodium acetate was used to study the potential toxicity to sewage sludge microorganisms. The test compound was degraded to 70% after 28 days. However, the degradation of 60 % was not reached during the 10 days window as required according to the guideline. Therefore, gestonorone was not ready biodegradable but showed significant degradation and can be expected to be inherently biodegradable in appropriate test designs. The test was performed according to GLP (report X515, study TXST20000174).