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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Desmodesmus subspicatus was exposed under static conditions for 72 h to one concentration (100 mg/L) of the test substance. No toxic effect was observed.

Key value for chemical safety assessment

EC50/LC50 for freshwater algae:
100 mg/L
EC10, LC10 or NOEC for freshwater algae:
100 mg/L

Additional information

A study was performed to assess the adverse effects of the substance on the growth rate (= rate of increase in cell density with time) of the planktonic freshwater algal species Desmodesmus subspicatus (former name: Scenedesmus subspicatus) over several generations. The study was conducted in accordance with Commission Regulation (EC) No 761/2009 amending Regulation No 440/2008, Method C.3 ‘Freshwater Alga and Cyanobacteria, Growth inhibition test’ (2009) which is equivalent to OECD Guideline for Testing of Chemicals No. 201 (2006). Exponentially growing algal cells were exposed for a period of 72 hours to a limit effective loading of nominally 100 mg/L of the substance dissolved in dilution water. Auxiliaries used to prepare the test media were an ultra turrax, a magnetic stirrer and a folded filter. The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions.

The results are expressed in terms of Effective Loadings (EL). As the substance is a multi-constituent substance and only poorly soluble in water, a suitable selective and sensitive chromatographically method for the determination of the substance in aqueous solutions could not be established. Therefore a Water Accommodated Fraction (WAF) was used to test effects at a limit effective loading of 100 mg/L, and no specific analysis was performed. The content of the test item during the exposure period was verified by DOC determination.