Branched and linear octadecanoic acid, esters with glycerol oligomers

Endpoint summary

Additional information

The dataset for aquatic toxicity is not complete for Reaction product of Isooctadecanoic acid, ester with oxybis[propanediol] (CAS 73296-86-3). In order to fulfil the standard information requirements, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from a structurally related substance 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 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). With 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.

Di(isooctadecanoic) acid, diester with oxydi(propanediol) (CAS 67938-21-0) was selected as the source substance. The source substance is one main component of the UVCB substance. Thus, it is considered to be suitable for the assessment of the target substance.

The toxicity to fish and algae was investigated using the source substance Di(isooctadecanoic) acid, diester with oxydi(propanediol) (CAS 67938-21-0). For toxicity to aquatic invertebrates a reliable guideline study for the target substance itself is available. All studies were performed according to internationally accepted guidelines and GLP (except for fish). Since the target and the source substance are poorly soluble in water, water accommodated fractions (WAFs) were prepared (if possible) for the test solutions in all tests (except for fish testing).

The acute toxicity to fish was investigated in a static test design performed comparably to OECD 203. Leuciscus idus melanotus was exposed to four concentrations in the range of 1 to 500 mg/L (nominal) under static conditions for 96 h. No mortality was observed after 96 h. Thus, a LC50 (96 h) > 500 mg/L (nominal) was derived.

The acute toxicity to aquatic invertebrates was investigated for the target substance itself and the suitable source substance according to OECD 202. The obtained EL50 (48 h) values from both studies were in the same order of magnitude, supporting the selected read-across approach. In the key study with the target substance D. magna was exposed to five nominal loading rate WAFs between 6.25 – 100 mg/L for 48 h in a static exposure regime. The obtained EL50 (48 h) was > 50 mg/L (nominal). The supporting study with the source substance Di(isooctadecanoic) acid, diester with oxydi(propanediol) confirmed the result of the key study. The derived EL50 (48 h) was > 50 mg/L. All effect values were based on the nominal loading rates of the test item. In both studies (key and supporting) immobilization of > 50% was recorded at the highest loading rate of 100 mg/L. Since the substances are surface active and form micelles in contact with water, this loading rate was excluded from assessment (see water solubility study in IUCLID section 4.8). There is strong evidence that the observed effects are physical effects rather than intrinsic effects due to micelle formation at least at the highest loading rate.

One OECD guideline study conducted with the structurally related source substance Di(isooctadecanoic) acid, diester with oxydi(propanediol) is available to cover the endpoint for the toxicity of the target substance to aquatic algae. The unicellular freshwater green alga Desmodesmus subspicatus was exposed to five nominal loading rates for 72 h. No inhibition of growth was recorded and the derived ErL50 and ErL10 (72 h) were > 250 mg/L (nominal). The corresponding NOELR and LOELR values were ≥ 250 mg/L (nominal) and > 250 mg/L (nominal), respectively.

In conclusion, the target substance is not likely to cause effects to aquatic organisms. No effects were observed in the available studies up to the solubility limit.