Fatty acids, C8-12, isopentyl esters

Endpoint summary

Additional information

Data on the ready biodegradability of Fatty acids, C8-12, isopentylester are not available. 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 Isopentyl laurate (CAS 6309-51-9) and Octyl octanoate (CAS 2306-88-9) was conducted. Fatty acids, C8-12, isopentylester is an UVCB substance comprising linear C8-C12 fatty acids esterified with a branched C5 alcohol (3-methyl-1-butanol; 2-methyl-1-butanol). The source substance Isopentyl laurate (CAS 6309-51-9), a branched C5 alcohole esterified with a linear C12 fatty acid chain, is a constituent of the target substances. Whereas Octyl octanoate (CAS 2306-88-9) is a C8 alcohole esterified with a linear C8 fatty acid chain. The read across substances cover the alcohol as well as the longest and shortest fatty acid chains of the target substance.

Based on the results determined for the source substances, the target substance Fatty acids, C8-12, isopentylesteris considered readily biodegradable (OECD 301 B; ≥ 89% 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. Furthermore, the substance is characterised by a low water solubility (2 - 50 µg/L at 20 °C, pH=6.3) and a low vapour pressure (≤ 0.66 Pa). The log Koc values calculated for the single substance components are >3. The 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, 2016). The substance is generally not expected to be present in the water column due to the low water solubility. The log koc values indicate 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, 2016). 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 < 0.0001 Pa at 20°C). An accumulation in air and 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 122.1 – 203.1 L/kg (BAF 138 – 224.6 L/kg) calculated for the main components (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic).