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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The analysis of the growth rate of the algal population within the 72 h exposure period showed an ErC50 of >100 mg/L, a NOEC[r] of 25 mg/L and a LOEC[r] of 50 mg/L for the test substance.

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
25 mg/L

Additional information

"should read" >100 mg/L

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 Algae and Cyanobacteria, Growth inhibition test’ (2009) which is equivalent to OECD Guideline for Testing of Chemicals No. 201 'Alga, Growth Inhibition Test' (2006). Exponentially growing algal cells were exposed for a period of 72 hours to different test concentrations of 6.3, 12.5, 25, 50 and 100 mg/l. The cell densities were measured in 24 hours intervals. Inhibition of the algal population was measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions. Growth rates were also used to calculate a No Observed Effect Concentration (NOEC) and a Lowest Observed Effect Concentration (LOEC) according to the Dunnett Test. After 72 hours exposure an ErC50 of >100 mg/L was obtained. The NOEC was 25 mg/l and the LOEC was 50 mg/l. The results are expressed in terms of nominal concentrations since no analytical monitoring was carried out.

This toxicity study is classified as acceptable and satisfies the guideline requirements for the acute Algae study.