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Toxicity to aquatic algae and cyanobacteria

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Description of key information

No toxicity up to the limit of water solubility.

Key value for chemical safety assessment

Additional information

No data are available on the toxicity of (Z)-N-Octadecyldocos-13-enamide (CAS No. 10094-45-8) to aquatic algae. Therefore data from the analogue substance (Z)-N-octadec-9-enylhexadecan-1-amide (oleyl palmitamide, CAS 16260-09-6) were used as read across. This read-across is in accordance with Regulation (EC) No. 1907/2006 Annex XI, 1.5 and justified in detail in the overall summary (IUCLID Chapter 6.1) and within the analogue justification attached in IUCLID Section 13.

A study was performed to assess the effect of (Z)-N-octadec-9-enylhexadecan-1-amide (oleyl palmitamide, CAS 16260-09-6)on the growth of the green alga Pseudokirchneriella subcapitata. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (2006) No 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" referenced as Method C.3 of Commission Regulation (EC) No 761/2009.

The test substance is highly insoluble in water and pre-study solubility work conducted indicated that it was not possible to obtain a testable solution of the test item using traditional methods of preparation e. g. ultrasonication and high-shear mixing. A pre-study media preparation trial indicated that the use of a saturated solution method of preparation was most appropriate for this test item.Exposure of Pseudokirchneriella subcapitata to the test item gave EC50 values of greater than 100% v/v saturated solution. The No Observed Effect Concentration was 100% v/v saturated solution.Analysis of the 100% v/v saturated solution test preparation at 0 hours showed a measured test concentration of less than the limit of quantitation (LOQ) of the analytical method employed, which was determined to be 0.014 mg/L. Analysis of the test preparation at 72 hours showed a measured test concentration of 0.015 mg/L. This study showed that there were no toxic effects at saturation.