Docosyl stearate

Endpoint summary

Additional information

The dataset for aquatic toxicity of Docosyl stearate (CAS 22413-03-2) is not complete. Therefore, the aquatic toxicity of the target substance was assessed by a read-across approach to structurally and chemically closely related source substances in order to fulfill the standard information requirements laid down in Annex VIII of Regulation (EC) No 1907/2006. Read-across was performed in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5.

According to Article 13(1) of this regulation, "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.” For aquatic toxicity in particular, 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). In regard to the general rules for grouping of substances and the read-across approach, the regulation specifies (Annex XI, Item 1.5) that 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. A detailed justification of the analogue approach is attached in IUCLID section 13.

The target substance Docosyl stearate (CAS 22413-03-2) is a mono-constituent substance and is an aliphatic ester composed of a saturated linear fatty acid (C18, stearic acid) esterified with an alcohol (C22, docosanol). In the present dossier, the target substance will be assessed on the basis of aquatic toxicity data compiled from the source substances dodecyl oleate (CAS 36078-10-1), 2-octyldodecyl isooctanoate (CAS 93803-87-3) and 9-Octadecenoic acid (Z)-, 9-octadecenyl ester, (Z)- (CAS 3687-45-4). The source substance dodecyl oleate (CAS 36078-10-1) consists of a branched C18 fatty acid and a linear C12 alcohol. The source substance 2-octyldodecyl isooctanoate (CAS 93803-87-3) mainly consists of branched C18 fatty acids and linear C20 alcohols. The source substance 9-Octadecenoic acid (Z)-, 9-octadecenyl ester, (Z)- (CAS 3687-45-4) mainly consists of a branched C18 fatty acids and linear C18 alcohols. The source substances were selected on the basis of structural similarities and similarities in properties and/or activities to the target substance, with due regard to requirements for adequacy and reliability of data. Therefore, the source substances are considered suitable representatives for the assessment of the aquatic toxicity of the target substance. Based on the high degree of similarity between the structural and physico-chemical properties of the target and selected source substances, it is assumed that the target substance will exhibit a similar ecotoxicological profile as the source substances. Where applicable, environmental and human health effects of the target substance are predicted by interpolation or extrapolation from source substance data in accordance with Annex XI, Item 1.5, of Regulation (EC) No 1907/2006. A detailed read-across justification is provided in IUCLID section 13.

By means of the read-across approach, guideline studies from the source substances are available for the short-term toxicity of the target substance to fish and algae as well as for the long-term toxicity to aquatic invertebrates and to algae. Due to the extremely low water solubility of the target substance (< 0.504 mg/L, OECD 105), the long-term testing on aquatic invertebrates was considered necessary to fully assess the potential aquatic hazard of the target substance. In addition, one experimental study is available for the toxicity to microorganisms.

All available studies with source substances were conducted according to internationally accepted guidelines and GLP. The source substance Docosyl stearate (CAS 22413-03-2) did not indicate any toxicity up to the water solubility limit for freshwater fish, daphnia and aquatic algae. Since the target substance is poorly soluble in water, a chronic study with Daphnia magna instead of an acute study was considered to be relevant in order to assess to toxicity to aquatic invertebrates adequately. Data on the toxicity to microorganisms were used from a respiration inhibition study where no effects were recorded. Thus, the inhibition process in sewage treatment plants is not considered to be inhibited.

Based on the high degree of structural and chemical similarity between the target and the selected source substances, the target substance is expected to exhibit a similar ecotoxicological profile as the source substances. Based on the available results from the target substance it can be concluded that Docosyl stearate (CAS 22413-03-2) has no toxic effects on freshwater organisms up to the limit of the water solubility.