10-Undecenoic acid, monoester with 1,2,3-propanetriol

Endpoint summary

Additional information

Data investigating the aquatic toxicity of Glyceryl undecylenate (CAS 123759-97-7) are not available.
In accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from structurally related substances Glyderides, C14-18 and C16-18 unsatd. mono-, di- and tri- (CAS 91052-28-7) and Glycerides, C8-10, mono- and di- (CAS 85536-07-8) was conducted to fulfil the standard information requirements. 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 aquatic 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). According to Annex XI, Item 1.5, of Regulation (EC) No 1907/2006 substances can be considered similar if their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity.

The target and the source substances are esters of a tri-functional alcohol (glycerol) with one or more carboxylic (fatty) acid(s) chain(s). The alcohol moiety (glycerol) is common to all analogue substances. The fatty acid moiety comprises carbon chain lengths from C8-C18 and includes mainly linear saturated alkyl chains, but also unsaturated chains bound to the alcohol, resulting in mono-, di-, and tri-esters. The target substance and the source substance Glyderides, C14-18 and C16-18 unsatd. mono-, di- and tri- (CAS 91052-28-7) are characterised by a low water solubility (<1 mg/L). The water solubility of the second source substance Glycerides, C8-10, mono- and di- (CAS 85536-07-8) is higher compared to the target substance (46 mg/L at 20 °C). The read across is therefore considered as a worst case approach. The available short-term and long-term studies indicate that the source substances are not acutely or chronically toxic to aquatic organisms up to the limit of water solubility of the source substances.

In the acute toxicity studies conducted with the source substance Glyderides, C14-18 and C16-18 unsatd. mono-, di- and tri- (CAS 91052-28-7) EL/LL50 values >100 mg/L were determined for fish, aquatic invertebrates and algae. The reported LL/EL50 values for the second source substance Glycerides, C8-10, mono- and di- (CAS 85536-07-8) for fish, aquatic invertebrates and algae were 75, 218.2 and 49 mg/L, respectively. The determinded NOEC for algae was 20.7 mg/L. In this test, the algae were reported to be encased by small dispersed particles in the suspension (confirmed by microscopical observation). Therefore, a physical interference of test substance particles with algae cells may also have contributed to the observed effect. The Guidance on information requirements and chemical safety assessment, Chapter R.7b, states that poorly water-soluble substances often have technical difficulties during aquatic testing, therefore one should treat results from tests above the limit of solubility with care and they “should not be interpreted as pelagic toxicity, but as confounded by physical effects” (ECHA, 2014). This also may have been the case in the two experimental studies on the source substance Glycerides, C8-10 mono- and di (CAS 85536-07-8) conducted with fish and aquatic invertebrates. Due to the readily biodegradable nature of the substance, such high concentrations are no expected to be reached in natural waters. Therefore, in accordance with the 5th ATP of Regulation (EC) No. 1272/2008, the substance was not classified as dangerous for the environment. The assumption is supported by a study on phase behaviour of lipid/surfactant/water phases demonstrating the technical difficulties for aquatic toxicity testing of this type of Glycerides (Prajapati et al., 2012; see IUCLID section 6.1.4).

The assessment of the toxicity to microorganisms is based on the toxicity control of the biodegradation test performed with the source substance Glycerides, C8-10 mono- and di (CAS 85536-07-8). The ready biodegradability study was conducted according to OECD 301B including a toxicity control with 46.9 mg/L test material (Flach, 2012). A degradation rate of 81.1% within 14 days was determined in the toxicity control clearly indicating the lack of toxic potential of Glycerides, C8-C10, mono- and di- to activated sludge microorganisms. Therefore, the test item concentration of 46.9 mg/L allows to derive the NOEC as ≥ 46.9 mg/L.

Based on the result from structurally related source substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) it can be concluded that Glyceryl undecylenate (CAS 123759-97-7) is not acutely or chronically toxic to freshwater organisms up to the limit of the water solubility (WS < 1 mg/L).