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Environmental fate & pathways

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Glyceryl undecylenate (CAS 123759-97-7) is considered readily biodegradable according to OECD criteria (69-95% in 28 d, read across). Due to the ready biodegradability a persitency of the substance in the environment is not expected. Abiotic degradation by hydrolysis is not relevant for the substance as indicated by QSAR calculations resulting in estimated half-lives in water ranging from 2.63 – 7.71 years (at pH 7) and 96.13 to 281.6 days (at pH 8). The substance is furthermore characterised by a low water solubility (8.5 - 182.5 µg/L at 20 °C, pH=6.3) and a low vapour pressure (< 0.0001 Pa at 20 °C). Together with the estimated high log Koc of single substance components (1.2 – 4.32) these characertistics indicate that the substance would mainly distribute to soil and sediment when released to the environment.

However, an exposure of these environmental compartments is unlikely, since the substance is expected to be extensively eliminated in conventional sewage treatment plants. In the case insoluble chemicals enter a standard Sewage Treatment Plant (STP), they will be extensively removed in the primary settling tank and fat trap and thus, only limited amounts will get in contact with activated sludge organisms, according to the Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2014). Due to the insolubility the substance is not expected to be present in the water column. The log Koc range of 1.2 – 4.32 for the main components, indicates a potential for adsorption to sewage sludge. Thus, a reduction of the substance concentration in the water column due to adsorption to sewage sludge is possible (Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2014). In conclusion, the concentration of the substance in conventional STP effluents is expected to be low.

The volatilization potential of the substance is negligible (VP < 0.0001 Pa at 20°C). If the substance should be present in the atmosphere, a rapid photodegradation is expected based on the estimated half-lives in air, ranging from 7.31 – 4.63 hours (AOPWIN 1.92 program). Based on the above information, accumulation in air, subsequent transportation and deposition into other environmental compartments is not anticipated.

Due to the rapid environmental biodegradation and metabolization via enzymatic hydrolysis a relevant uptake and bioaccumulation in aquatic organisms is not expected. Enzymatic breakdown will initially lead to the free fatty acid and glycerol. These hydrolysis products will be metabolised and excreted in fish effectively (Tocher, 2003). The low bioaccumulation potential is also indicated by BCF values ranging from 3.49 – 6.78 L/kg calculated for the main components (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic).

A detailed reference list is provided in the technical dossier (see IUCLID, section 13) and within the CSR.