Isobutyl laurate

Endpoint summary

Additional information

The biodegradability of isobutyl laurate (CAS 37811-72-6) was tested in natural seawater (OECD 306; 55% in 28 d). A ready biodegradability of the substance in marine environments could not be demonstrated. Generally the the potential for degradation is lower in seawater compared to freshwater degradation tests (Guidance on information requirements and chemical safety assessment, Chapter R.7b; ECHA, 2016). Thus the assessment of ready biodegradability was furthermore based on read-across to the structurally related substances isopentyl laurate (CAS 6309-51-9) and isopropyl laurate (CAS 10233-13-3) 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.

The target substance isobutyl laurate (CAS 37811-72-6) is a branched C4 alcohol esterified with a linear C12 fatty acid chain. The source substances isopentyl laurate (CAS 6309-51-9) and isopropyl laurate (CAS 10233-13-3) are also branched alcohols (C3 and C5) esterified with a linear C12 fatty acid chain. Thus, the read across substances cover the fatty acid chain length of the source substance as well as the characteristics of the alcohole moiety of the source substance.

Based on the results determined for the source substances, the target substance isobutyl laurate (CAS 37811-72-6) is considered readily biodegradable (≥ 67% 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 14.15 years at pH 7 and 1.41 years at pH 8 respectively. The substance is furthermore characterised by a low water solubility, a low vapour pressure and a log Koc value >3. 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, 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: 0.02 Pa at 20°C). 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 a calculated BCF value of 183.1 L/kg and a BAF value of 215.7 L/kg (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic).

References:

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