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Toxicity to aquatic algae and cyanobacteria

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Description of key information

No effects up to the limit of the water solubility of the substance.
EC50 (72 h) = 28 mg a.i./L (nominal) for Scenedesmus subspicatus (DIN 38412, part 9)
EC10 (72 h) = 21.7 mg a.i./L (nominal) for Scenedesmus subspicatus (DIN 38412, part 9)

Key value for chemical safety assessment

Additional information

One study investigating the toxicity of D-Glucose, reaction products with alcohols C16-18 (even numbered) (excess) to aquatic algae is available. In this key study performed according to DIN 38412, part 9 and GLP, Scenedesmus subspicatus was exposed to nominal concentrations of 10, 30, 100, 300, 1000 and 3000 mg/L of a product containing 30% APG and 70% fatty alcohol in a static test design. Analytical verification of the test substance concentrations was not performed. As a result, an EC50 (72 h) value of 28 mg/L (nominal) and an EC10 (72 h) value of 21.7 mg/L (nominal) was reported. Hence it can be concluded that there is no toxicity to aquatic algae up to the limit of the water solubility of the substance (Henkel, 1993).

Two other supporting studies investigated the toxicity of C16 fatty alcohol and C18 fatty alcohol, respectively, to Scenedesmus subspicatus according to GLP and DIN 38412, part 9 (Henkel, 1992 and 1992). These data from category member substances are considered suitable for read-across based on a category approach. The substances were applied at 10, 30, 100, 300, 1000 mg/L (and 3000 mg/L for C18 fatty alcohol) nominal in a static design, however these concentration are far above the water solubility limit of the substances. As a result, EC50 (96 h) values of 690 and > 10 mg/L for growth rate were stated for C16 and C18 fatty alcohol, respectively. In the study on C18 fatty alcohols, additional treatments with filtrated test solutions were performed, resulting in an EL50 of 0.64 mg/L, still above the water solubility limit, indicating that physical rather than toxic effects are exerted. Accordingly it can be confirmed that there is no toxicity to algae up to the limit of the water solubility of the substances.

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 category justification attached 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 IUCLID Section 13 and the overall summary (IUCLID Chapter 6.1), all reliable data in the category support the hazard assessment of each category member by showing a consistent pattern of results.