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Environmental fate & pathways

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A reliable measured biodegradation study in water for FX511 is available and included in the dossier. Reliable studies on the biodegradation in sediment and soil are not available, however waivers are applied for these endpoints.

 

A reliable measured biodegradation study for FX511 is available and included in the dossier. Clark (2012) conducted a reliable (Klimisch 1) GLP compliant study according to OECD 301 B (CO2 Evolution Test) method. The biodegradability of FX511 exposed to microorganisms derived from activated sludge obtained from a municipal wastewater treatment plant was investigated under aerobic exposure conditions. After 28 days the test substance showed 92% degradation, with an initial test concentration of 10 mgC/L. Greater than 60% degradation occurred within 10 day window. The study concluded that FX511 can be considered to be readily biodegradable, passing the 10-day window. Consequently this study will be taken for the biodegradation in water endpoint.

 

Waiver. In accordance with Column 2 of REACH Annex IX, the simulation test on ultimate degradation in surface water, the soil simulation test and the sediment simulation test (required in Sections 9.2.1.2, 9.2.1.3 and 9.2.1.4 respectively) do not need to be conducted as direct or indirect exposure of soil is unlikely or if the substance is readily biodegradable. Exposure potential is expected to be unlikely as substance is readily biodegradable. In the environment, ready biodegradability means it can be assumed that FX511 will be biodegraded within the STP process and as a consequence a transfer to the aquatic compartment via STP effluent is not expected. Furthermore, for substances not passing the STP-process but being readily biodegradable, it can be assumed that they will be also biologically degraded in the surface water within a short time. Also, the substance’s low log octanol-water partition coefficient (Log Kow) of 2.98 at a neutral pH indicating low adsorptive potential. Therefore, no additional degradation testing is necessary.