Fatty acids, C8-12, isopentyl esters

Endpoint summary

Additional information

Experimental data on the toxicity of Fatty acids, C8-12, isopentylester to terrestrial organisms are not available. In order to fulfil the standard information requirements set out in Annex IX, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across to the structurally related source substance Isopropyl myristrate (CAS 110-27-0) was conducted.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular for human toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across).

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006 whereby substances may be predicted as similar provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity.

Fatty acids, C8-12, isopentylester is an UVCB substance comprising linear C8-C12 fatty acids esterified with a branched C5 alcohol. The source Isopropyl myristate (CAS 110-27-0) is a branched alcohole (C3) esterified with a linear fatty acid chain (C14).

Based on the ecotoxicological profile of Fatty acids, C8-12, isopentylester a toxicity of the substance to terrestrial organisms is considered unlikely. The substance is characterised by a low water solubility (WS: 2 - 50 µg/L at 20 °C). The Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2016) states that once insoluble chemicals enter a standard 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. Consequently a significant release to the environment of the substance via STP effluents is not expected and thus an exposure of terrestrial organisms is unlikely.

However, when terrestrial organisms are exposed to the substance toxic effects are not expected as demonstrated by a short-term toxicity study with earthworms available for the analogue substance isopropyl myristate (CAS 110-27-0). The toxicity of isopropyl myristate (CAS 110-27-0) to earthworms was evaluated by Steber (1999). Eisenia fetida was exposed to the test substance for 14 days at a concentration of 20000 mg/kg dw (limit test). No effects on survival during the exposure period were reported, leading to a LC50 (14 d) > 20000 mg/kg dw.

As stated in the ECHA Guidance R.7c the absence of chronic or long-term toxicological effects in aquatic organisms up to the substance solubility limit, can be used as part of a Weight of Evidence argument to modify/waive the data requirements of Annex IX and X (ECHA, 2014). Since no effects on Daphnia were observed up to the limit of water solubility in the available chronic toxicity study it is assumed that long term tests on terrestrial organisms will not result in a different outcome. Furthermore, bioaccumulation or biomagnification through the food chain of the substance is not likely. Though the high log Pow value (log Pow >5) indicates a potential of the substance to bioaccumulate a relevant uptake is not likely. Due to a metabolization via enzymatic hydrolysis a relevant uptake and bioaccumulation in terrestrial organisms is not expected. This is supported by low BCF and BAF values (BCF 122.1 – 203.1 L/kg; BAF 138 - 224.6 L/kg (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic)) calculated for the main substance components, indicating a low bioaccumulation potential. The available read across studies on the toxicity of the source substances to aquatic microorganisms determined no inhibition of microorganisms (respiration and growth). The Guidance Document (ECHA, 2014) states that a test on soil microbial activity will only be additionally necessary for a valid PNEC derivation if inhibition of sewage sludge microbial activity has occurred. Further evidence on the lack of toxicity is available from literature data. These data show that soil microorganism communities are well capable of degrading fatty acid esters (Hita et al., 1996 and Cecutti et al., 2002) and use them as energy source (Banchio & Gramajo, 1997). Overall, the substance is unlikely to pose a risk to terrestrial organisms based on a) the lack of exposure and b) the lack of adverse effects and low bioaccumulation potential.