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Experimental data on the toxicity of Fatty acids, C18-unsatd., dimers, reaction products with fatty acids, C14-18 and C16-18-unsatd. and propylidynemethanol 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 substance2-ethyl-2-(((1-oxoisooctadecyl)oxy)methyl)-1,3-propanediyl bis (isooctadecanoate) (CAS 68541-50-4)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.

The target substance Fatty acids, C18-unsatd., dimers, reaction products with fatty acids, C14-18 and C16-18-unsatd. and propylidynemethanol (CAS 162353-70-0) mainly consists of mixed esters (mono-, di- or tri-component) of fatty acid dimers of predominantly octadecenoic acid (C18 unsaturated) and octadecenoic acid with propylidynemethanol. The source substance2-ethyl-2-(((1-oxoisooctadecyl)oxy)methyl)-1,3-propanediyl bis (isooctadecanoate) (CAS 68541-50-4) is a triester of trimethylolpropane with C18iso fatty acid chains.

Based on the ecotoxicological profile of of Fatty acids, C18-unsatd., dimers, reaction products with fatty acids, C14-18 and C16-18-unsatd. and propylidynemethanol a toxicity of the substance to terrestrial organisms is considered unlikely. The substance is characterised by a low water solubility (WS <1 mg/L). 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 2-ethyl-2-(((1-oxoisooctadecyl)oxy)methyl)-1,3-propanediyl bis (isooctadecanoate). The toxicity of 2-ethyl-2-(((1-oxoisooctadecyl)oxy)methyl)-1,3-propanediyl bis (isooctadecanoate) to earthworms was evaluated in a study following OECD guideline 222 (Harlan Laboratories Ltd., 2013). Eisenia fetida was exposed to the test substance for 56 days at test substance concentrations of a concentration of 62.5, 125, 250, 500 and 1000 mg/kg dry soil. No effects on survival during the exposure period were reported, leading to a NOEC (28 d) ≥ 10000 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 >10) 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. The BCF and BAF values calculated for the main substance components were 0.89 L/kg (Arnot-Gobas estimate, including biotransformation, upper trophic). Even though Fatty acids, C18-unsatd., dimers, reaction products with fatty acids, C14-18 and C16-18-unsatd. and propylidynemethanol is outside the applicability domain of the model, the estimation can be used as supporting indication of low bioaccumulation potential. The model training set is only consisting of substances with log Kow values of 0.31 - 8.70. But it supports the tendency that substances with high log Kow values (> 10) have a lower potential for bioconcentration as summarized in the ECHA Guidance R.11 and they are not expected to meet the B/vB criterion (ECHA, 2014).

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.