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There is only limited data available for the aquatic toxicity of the target substance Fatty acids, C16, C18 and C18-unsaturated, C12-15 alcohol (linear and branched), esters. Therefore, the aquatic toxicity of the target substance was assessed by means of a read-across approach, through which additional data from a structurally and chemically closely related source substance was compiled in order to fulfill the standard information requirements laid down in Annex XI of REACh 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 of Regulation (EC) No 1907/2006 "General Requirements for Generation of Information on Intrinsic Properties of substances", information on intrinsic properties of substances may be generated by means other than tests e.g. from information from structurally related substances (grouping or read-across), provided that conditions set out in Annex XI are met. In Annex XI, "General rules for adaptation of this standard testing regime set out in Annexes VII to X”, it is stated that “substances whose physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity may be considered as a group, or ‘category’ of substances. This avoids the need to test every substance for every endpoint and avoids unnecessary animal testing”.

The target substanceFatty acids, C16, C18 and C18-unsaturated, C12-15 alcohol (linear and branched), estersis a UVCB substance consisting of four main constituents which are long-chain aliphatic esters with fatty acid chain lengths ranging from 16 to 18 (unsaturated and branched) and C12 – C15 alcohol components. In the present dossier, the target substance will be assessed on the basis of aquatic toxicity data compiled from the source substance Dodecyl oleate (CAS 36078-10-1). The source substance was selected on the basis of structural similarities and similarities in properties and/or activities to the target substance, with due regard of the requirements for adequacy and reliability of data. The source substance is a UVCB substance and is characterized by similar fatty acid chain lengths (C18:1) and alcohol components (C12) as the target substance. Therefore, the source substance is considered a suitable representative 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 source substance, it is assumed that the target substance will exhibit a similar ecotoxicological profile as the selected source substance. 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 are available for the short-term toxicity of the target substance to aquatic algae and fish as well as for the long-term toxicity to aquatic invertebrates and algae. All the available aquatic toxicity studies were performed with the source substance Dodecyl oleate (CAS 36078-10-1) and in compliance with GLP. Due to the extremely low water solubility of the target substance (< 6.57 µg/L, OECD 105), long-term testing on aquatic invertebrates was considered necessary to fully assess the potential aquatic hazard. In addition, one experimental study is available for the toxicity to microorganisms.

 

The study on the short-term toxicity to fish was conducted according to OECD guideline 203. After 96 h of exposure of the model organism Danio rerio to a Water Accommodated Fraction of the test item (limit test), no mortality was observed and chemical analysis of the test solution resulted in concentrations below the analytical detection limit of 0.005 mg/L, reflecting the very low water solubility of the test item. Thus, it was concluded that the test item does not cause short-term toxic effects to fish up to the limit of water solubility.

The study on the long-term toxicity to aquatic invertebrates was conducted according to OECD guideline 211. After 21 d of exposure of the model organism Daphnia magna to five testing levels prepared as Water Accommodated Fractions no effects on reproduction were observed and the chemical analysis of test solutions resulted in concentrations below the analytical detection limit of 0.005 mg/L reflecting the very low water solubility of the test item. Thus, it was concluded that the test item does not cause chronic effects to aquatic invertebrates up to the limit of water solubility.

The study on the toxicity to aquatic algae was performed according to OECD 201. After 72 h of exposure of the model organism Desmodesmus subspicatus to five exposure levels prepared as Water Accommodated Fractions, no effects on growth rate and yield were observed and the measured test item concentrations in the test solutions were below the limit of quantification (< 0.005 mg/L). Thus, it is concluded that the test item does not cause toxic effects to aquatic algae up to the limit of water solubility.

The study on the toxicity to activated sludge microorganisms was conducted according to OECD 209.

After a 3 h incubation of the activated sludge with the test item, no inhibition of the respiration rate was observed and it was concluded that the test item does not cause toxicity to aquatic microorganisms.

In summary, the compiled data for short-term toxicity to two trophic levels (fish and aquatic algae) and long-term toxicity to two trophic levels (aquatic invertebrates and algae) neither indicate any short-term nor long-term toxicity to aquatic organisms up to the limit of water solubility. Furthermore, no inhibitory effects towards aquatic microorganisms of activated sludge were recorded.

 

Due to the ready biodegradability (89.9% in 28 d, OECD 301 B) and the high adsorption potential (log Koc > 5.0, KOCWIN v.2.00) of the target substance, the substance is expected to be eliminated from sewage treatment plants to a high extent. Release to the aquatic environment and subsequent exposure of sediment is therefore very unlikely. Furthermore, the substance is a long-chain aliphatic ester. Therefore, in the unexpected event where absorption of the substance by aquatic organisms should occur, it is expected to be rapidly metabolized via enzymatic hydrolysis into its corresponding fatty acids and fatty alcohols, which are known from literature to metabolize well in aquatic organisms. Against this background, the overall potential for chronic exposure and for bioaccumulation in aquatic organisms is judged to be very low.

Therefore, it can be concluded that the target substance Fatty acids, C16, C18 and C18-unsaturated, C12-15 alcohol (linear and branched), esters presumably does not cause short-term or long-term toxicity to aquatic organisms up to the limit of water solubility (< 6.57 µg/L at 20 °C, pH 6.3, OECD 105) and is not expected to affect the degradation process in commercial sewage treatment plants.

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