Fatty acids, C12-18 (even-numbered), 3-methylbutyl esters

Endpoint summary

Additional information

Data on the ready biodegradability of Fatty acids, C12-18, even numbered, 3-methylbutyl esters (CAS 1314763-50-2) are not available. In order to fulfil the standard information requirements set out in Annex VII, 8.5, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from the structurally related substances Isopropyl palmitate (CAS 142-91-6) and Isopentyl laurate (CAS 6309-51-9) was conducted. Fatty acids, C12-18, even numbered, 3-methylbutyl esters (CAS 1314763-50-2) is an UVCB substance comprising linear C12-C18 fatty acids esterified with a branched C5 alcohol. The source substances are C12 and C14 fatty acids esterified with a branched C3 or C5 alcohol. The read across substances cover the shorter fatty acid chains of the target substance. The ready biodegradability of components with longer fatty acid chains was predicted by reliable QSAR calculation (VegaNIC version 1.0.8). The components were in the applicability domain of the model.

Based on the results determined for the source substances and by QSAR calculation, the target substance Fatty acids, C12-18, even numbered, 3-methylbutyl esters (CAS 1314763-50-2) is considered readily biodegradable (OECD 301 B >90 % in 28 d) according to the OECD criteria. Due to the ready biodegradability persistency 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 of 331.88 days at pH 7 and 9.09 years at pH 8 respectively. The substance is furthermore characterised by a low water solubility and a low vapour pressure. Together with a high log Koc (log Koc >4) estimated for the single substance components these characteristics 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 largely removed in the primary settling tank and fat trap and thus, only limited amounts will get in contact with activated sludge organisms (Guidance on information requirements and chemical safety assessment, Chapter R.7b; ECHA, 2014). The substance is generally not expected to be present in the water column due to the low water solubility. Furthermore the log Koc range of 4.08 – 5.64 for the main components indicates a potential for adsorption to sewage sludge. Thus, further reduction of the substance concentration in the water column due to adsorption is possible (Guidance on information requirements and chemical safety assessment, Chapter R.7b; ECHA, 2014). Thus based on the ready biodegradability and substance characteristics the substance concentration in conventional STP effluents is expected to be neglectible.

The volatilization potential of the substance is very low (VP < 0.01 Pa at 20°C). Nevertheless, if released into the atmosphere, the substance is expected to be rapidly photodegraded based on the estimated half-lives in air, ranging from 14.04 – 30.32 hours (AOPWIN 1.92 program). An accumulation in air, subsequent transportation and deposition into other environmental compartments is not expected.

Due to the rapid environmental biodegradation and metabolization of the substance 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 a primary branched alcohole. 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 0.325 to 2.087 L/kg calculated for the main components (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic).