Isooctadecyl isooctadecanoate

Endpoint summary

Additional information

There are no data available investigating the aquatic toxicity of isooctadecyl isooctadecanoate (CAS 41669-30-1). 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.

Ecotoxicological parameters for the aquatic toxicity of the target and the source substances are provided in the following table.

ID	CAS	Short term toxicity to fish	Long term toxicity to fish	Short term toxicity to aquatic invertebrates	Long term toxicity to aquatic invertebrates	Toxicity to aquatic algae	Toxicity to microorganisms
Target	41669-30-1	RA: CAS 93803-87-3	Waiving based on CSA	RA: CAS 93803-87-3	RA: CAS 93803-87-3 RA: CAS 3687-45-4	RA: CAS 93803-87-3	RA: CAS 93803-87-3
Source 3	93803-87-3	Experimental result: LL50 (96 h) > 100 mg/L	--	Experimental result: EL50 (48 h) > 86 mg/L	Expert statement: Study technically not feasible	Experimental result: EL50 (72 h) >100 mg/L NOELR (72 h) ≥ 100 mg/L	Experimental result: NOEC (14 d) ≥ 14.2 mg/L
Source 4	3687-45-4	--	--	--	Experimental result: NOELR (21 d) >100 mg/L	--	--

 

The above mentioned 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 the same endpoints for isooctadecyl isooctadecanoate (CAS 41669-30-1). The target substance is characterized by a branched C18 fatty acid esterified with branched C16 and C18 alcohol. Both source substances are structurally very similar to the target substance. They are characterized by isostearic acid esterified with a branched alcohol (2-octyldocdecanol) and oleic acid esterified with oleyl alcohol, respectively. A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

All available experimental data on the source substances performed according to internationally accepted guidelines indicate no evidence of acute and chronic toxicity to aquatic organisms. Data for all three trophic levels are available. 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 be 0.044 mg/L at 20 °C.

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 on aquatic invertebrates was considered to be necessary to assess the aquatic toxicity. The available study performed with the suitable source substance (Z)-octadec-9-enyl oleate (CAS 3687-45-4) 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 of the source substance 2-octyldodecyl isooctanoate (CAS 93803-87-3). 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 the occurrence of bioavailable concentrations of the test substance in the water phase is not very likely, i.e. of concentrations high enough to induce any acute or chronic effects in aquatic organisms.

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. Available information taken from a biodegradation study with the source substance 2-octyldodecyl isooctanoate (CAS 93803-87-3) performed with activated sludge from sewage treatment plants did not indicate a risk since biodegradation was not inhibited.

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 isooctadecyl isooctadecanoate (CAS 41669-30-1) 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.

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