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There are no data available investigating the aquatic toxicity of 2-octyldodecyl myristate (CAS 22766-83-2). 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 and all source substances are considered to be similar on the basis of the structural similar properties and/or activities. The available endpoint information on the source substances is used to predict comparable results for the target substance 2-octyldodecyl myristate (CAS 22766-83-2).
The target substance is characterised as an ester of C18 iso branched fatty acid esterified with 2-octyldodecan-1-ol. The two source substances are structurally very similar to the target substance. 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) is characterised by a longer fatty acid chain length (C18 iso branched) and by the same alcohol component (2-octyldodecan-1-ol). Fatty acids, C8-10, C12-18-alkyl esters (CAS 95912-86-0) is as UVCB substance consisting of fatty acids C8-C10 esterified with fatty alcohols C12-C18.
A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

All available experimental studies available for the suitable source substances were performed according to internationally accepted guidelines. They cover all three trophic levels of an aquatic ecosystem. No toxicity was observed up to the limit of water solubility in all available experimental studies. The water solubility of the target substance was determined to be17.7 µg/L, at 19°C, pH 6.3.

The short-term toxicity to fish was determined in a standard OECD guideline study according to OECD 203 (from the source substance CAS 93803-87-3). No mortality was observed after 96 h resulting in a LL50 > 100 mg/L (i.e. above the water solubility limit). The same was recorded for the short-term toxicity to aquatic invertebrates and to aquatic algae. No immobilization 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 with aquatic invertebrates was considered to be necessary to assess the aquatic toxicity. The available study performed with the suitable source substance Fatty acids, C8-10, C12-18-alkyl esters (CAS 95912-86-0) resulted in a NOELR (21 d) ≥ 10 mg/L indicating no effects on reproduction up to the limit of water solubility. Moreover, a statement from the performing laboratory of a long-term study with the suitable source substance 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) is available indicating that a long-term study is technically not feasible.

Long-term toxicity testing to fish was not considered to be necessary since there was no evidence from the available data that fish are more sensitive compared to aquatic invertebrates. No toxicity to fish was observed in the available acute tests. Thus, in order to avoid unnecessary vertebrate testing, no long-term testing with fish was proposed.

The degradation process in commercial sewage treatment plants is not suspected to be inhibited by the target substance. An experimental study with the source substance 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) did not indicate inhibition of degradation using activated sludge microorganisms.

Based on the result from structurally related read-across substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) it can be concluded that the target substance 2-octyldodecyl myristate 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 source substances support the read-across by showing a consistent pattern of results.

A detailed reference list is provided in the technical dossier (see IUCLID, section 13) and within CSR.