Octadecanoic acid, C16-20-branched alkyl esters

Endpoint summary

Additional information

There are no data available investigating the aquatic toxicity of Octadecanoic acid, C16-20-branched alkyl esters (CAS 85203-92-5). In order to fulfil the standard information requirements, 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 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).

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 as an ester of linear fatty acids and linear alcohols with different compositions of C16-C20 fatty acids and C16-C18 fatty alcohols (C18 fatty acid, C16 alcohol; C16 fatty acid, C18 alcohol; C18 fatty acid, C18 alcohol; C20 fatty acid, C16 alcohol). The source substances are structurally very similar to the target substance. The source substance 2-octyldodecyl isooctanoate (CAS 93803-87-3) is and ester of isooctanoate (C18 iso) and 2-octyldodecanol (C20 branched). Lauryl Oleate (CAS 36078-10-1) is specified as an ester of C18 unsaturated fatty acid and C12 fatty alcohol whereas the source substance 9-Octadecenoic acid (Z)-, 9-octadecenyl ester, (Z)- (CAS 3687-45-4) is an ester of C18 unsaturated fatty acid and C18 unsaturated alcohol.

A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

All available experimental studies on the source substances, performed according to internationally accepted guidelines, indicate no evidence of acute and chronic toxicity to aquatic organisms up to the limit of water solubility. The water solubility of the target substance was determined to be <10 µg/L at 20 °C, pH=6.3.
No inhibition of reproduction of Daphnia magna and no inhibition of growth of aquatic algae were observed in experimental studies according to OECD guidelines up to the limit of water solubility. Due to the low water solubility, long-term testing to aquatic invertebrates was considered to be more relevant compared to short-term testing in order to assess the aquatic toxicity. The available studies performed with suitable source substances resulted in a NOELR (21 d) ≥ 100 mg/L indicating no effects on reproduction up to the limit of water solubility. Moreover, an expert statement from a laboratory is available indicating that a chronic toxicity study with Daphnia magna is technically not feasible due to substance characteristics. Based on the high hydrophobicity, there is no analytical method sensitive enough to detect concentrations of the test substance in water samples. As a result, it is not possible to give any analytical support to the reproduction test with Daphnia magna. This analytical support is essential to meet the acceptability criterion for evidence that the actual concentration had been maintained within a 20% window during the total test period. Owing to the fact that the source substance is a liquid with water solubility below detection limit (< 0.05 mg/L) and a log Kow of > 7, it is not possible to prepare solutions that can be tested in a 21-day reproduction test with Daphnia magna. Further, these characteristics support the expectation that it will not be very likely that bioavailable concentrations of the test substance will ever occur in the water phase, i.e. concentrations high enough to induce any acute or chronic effects in aquatic organisms.

Based on the results from structurally related read-across substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) it can be concluded that Octadecanoic acid, C16-20-branched alkyl esters (CAS 85203-92-5) exhibits no toxic effects on freshwater organisms up to the limit of the water solubility. 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.