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The biotic and the abiotic degradation of Y-15099 (CAS 220727-26-4) were investigated in experimental studies. Testing on biotic degradation exhibited that the substance is not readily biodegradable but showed a moderate biodegradation potential of 56% after 28 days (Grützner, 2001). These results mainly reflect the biodegradation of the hydrolysis products since testing on hydrolysis indicated that the substance is hydrolytically unstable with a DT50 of 45.5 h under environmental conditions (pH 7). The DT50 at pH 4 was 0.628 h and 4.46 h at pH 9, respectively (Tarran and White, 2012). Thus, the bioavailability of Y-15099 is limited if released into the environment and the hydrolysis products have to be taken into account for the environmental assessment. Since the hydrolysis products were not identified in the hydrolysis study they were derived from the chemical structure. Octanoic acid, silanetriol, (3-mercaptopropyl)- and ethanol were estimated to be the initial hydrolytic degradation products.  

 

If Y-15099 is released into water it will mainly participate to sediment particles since the log Koc of = 3.6 indicates a potential to be adsorbed by organic carbon (Völkel, 2001). The log Koc for the hydrolysis products was calculated to be < 3 showing low potential for adsorption to soil and sediment particles (Müller, 2012). Evaporation from water into air is negligible due to the low calculated Henry’s Law constant of < 1 for Y-15099 and its hydrolysis products (Müller, 2012). The hydrolysis product ethanol, which is expected to participate mainly to the atmospheric compartment is well characterized and the expected half-life was estimated to be 10 - 36 h. It's photochemical ozone creation potential is considered to be moderate to low (OECD, 2004). Thus, it is concluded that accumulation in air and transport through the vapour phase into other environmental compartments is not relevant. Air is not a likely route of environmental contamination and no accumulation is expected. However, if emitted from the water phase into the air the substance and the hydrolysis products are susceptible to indirect photodegradation (Müller, 2012). 

 

The potential for bioaccumulation of Y-15099 was evaluated experimentally in a 60 d study according to OECD 305 with the carp Cyprinus carpio (Yakata, 2003). A BCF of 20 indicates a low potential for bioaccumulation. This study also reflects to hydrolyis products of the substance. The hydrolysis products silanetriol, (3-mercaptopropyl)- and ethanol have a log Kow < 3 assuming a low potential for bioaccumulation as well. Octanoic acid with a log Kow of 3.05 slightly exceeds the trigger value of 3. But a supporting QSAR calculation indicates a low potential for this hydrolysis product with a BCF of 83.64 L/kg wet weight (Müller, 2012).

References: OECD (2004): Ethanol. SIDS Initial Assessment Report For SIAM 19, Berlin, Germany, 19 - 22 October 2004. UNEP publications.