2-ethyl-2-(hydroxymethyl)-1,3-propanediyl dioleate

Endpoint summary

Additional information

There are no data available on the biodegradation of 2-ethyl-2-(hydroxymethyl)-1,3-propanediyl dioleate (CAS 25111-05-1). 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 structurally related substances 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 is characterized by C18 unsaturated fatty acid esterified trimethylolpropane (TMP) (mainly di- and triester). The selected source substances are structurally very similar to the target substance and are thus adequate for the assessment of biodegradability of the target substance. Fatty acids, C16-18 even numbered and C18-unsatd. triesters with propylidynetrimethanol (former CAS 57675-44-2) is characterized by C18, C18 unsatd fatty acids triesterified with TMP. Fatty acids, C16-18 (even numbered) and C16-18-unsatd. (even numbered), triesters with trimethylolpropane (CAS 68002-79-9) and Fatty acids, C8-10 (even), C14-18 (even) and C16-18 (even)-unsatd., triesters with trimethylolpropane (former CAS 85186-89-6) mainly consist of C18:1 FA triesterified with TMP. A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

The target substance 2-ethyl-2-(hydroxymethyl)-1,3-propanediyl dioleate (CAS 25111-05-1) is characterised by a low vapour pressure (VP < 0.0001 Pa at 20 °C, SPARC (v4.6)), a low water solubility (1.26 µg/L - 13.54 µg/L at 20 °C, pH = 6.3 (OECD 105), mean: 7.40 µg/L) and a high log Koc indicating a high adsorption potential to soil and sediment particles (log Koc ≥ 3.78, MCI method, KOCWIN v2.00). Based on the result from the selected source substances and valid QSAR predictions, the target substance is readily biodegradable (76.3 - 79.9% after 28 d (OECD 301B), 86% after 28 d (OECD 301F)). Thus, it is expected that an extensive elimination of the substance in sewage treatment plants will occur. In the case insoluble chemicals enter a standard Sewage Treatment Plant (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, according to the Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2014). As a result of the high adsorption potential of the substance (log Koc ≥ 3.78, MCI method, KOCWIN v2.00) a removal from the water column to a significant degree by adsorption to sewage sludge can be expected (Guidance on information requirements and chemical safety assessment, Chapter R.7b, (ECHA, 2014). In conclusion, the concentration of the substance in conventional STP effluents is presumably marginal. Abiotic degradation via hydrolysis is considered as not relevant for the substance. Calculations using HYDROWIN v2.00 predict half-lives > 1 year for the main components of the substance (Müller, 2015). Moreover, the substance is not volatile (VP < 0.0001 Pa at 20 °C) and thus evaporation to the air and subsequent transport through the atmosphere to other environmental compartments is not likely. However, if 2-ethyl-2-(hydroxymethyl)-1,3-propanediyl dioleate is released into air, the substance is susceptible to indirect photodegradation in air by OH-radicals as half-lives of less than 24 hours were calculated for the main components of the substance (Müller, 2015).

Based on the low water solubility and metabolism via enzymatic hydrolysis of the substance a relevant uptake and bioaccumulation in aquatic organisms is not expected. 2-ethyl-2-(hydroxymethyl)-1,3-propanediyl dioleate will be hydrolysed and the cleavage products can be further metabolized. In conclusion, bioaccumulation and biomagnification through the food chain of the substance is not expected. This is supported by low calculated BCF and BAF values of 0.893 - 19.84 and 0.893 - 30 L/kg (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic). Please refer to IUCLID Section 5.3 for a detailed overview on bioaccumulation of the substance.

As it can be seen in the data matrix of the analogue justification in IUCLID Section 13, all reliable data from the target and the source substances support the read-across by showing a consistent pattern of results.