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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

No effects up to the limit of water solubility based on available data (OECD 201).

Key value for chemical safety assessment

Additional information

Since no studies investigating the toxicity to algae of (Z)-octadec-9-enyl (Z)-docos-13-enoate (CAS 17673-56-2) are available for this endpoint, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read across to the structurally related category member dodecyl oleate (CAS 36078-10-1) was conducted.

The read-across substance dodecyl oleate is characterized by a smaller fatty acid chain (C18 unsatd. compared to C22 unsatd. (target)) and a smaller fatty alcohol chain length (C12 compared to C18 unsatd. (target)). The read-across substance will probably exhibit a higher water solubility and bioavailability in the water phase since the water solubility is dependent on the C-chain length of the fatty alcohol and fatty acid (Lide, 2005). This read-across is justified in detail in the overall summary (IUCLID Section 6.1) and within the category justification in IUCLID Section 13. In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substance was used for the assessment. Nevertheless, as it can be seen in the data matrix of the category justification in section 13 and the overall summary, all reliable data in the category support the hazard assessment of each category member by showing a consistent pattern of results.

The study with the read-across substance dodecyl oleate (CAS 36078-10-1) was performed according to OECD 201 under GLP conditions (Hafner, 2012). Desmodesmus subspicatus was exposed to the loading rates of five concentrations up to 100 mg/L. Analytical measurements resulted in concentrations below the detection limit (< 0.005 mg/L). The growth of algae was not inhibited resulting in a NOELR (72 h) ≥ 100 mg/L (nominal) and an EL50 (72 h) > 100 mg/L (nominal) based on the growth rate and yield.

Based on the result from one structurally related read-across substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which is characterized by a similar ecotoxicological profile and comparable structure, it can be concluded that (Z)-octadec-9-enyl (Z)-docos-13-enoate will not exhibit effects on algae up to the limit of water solubility.