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Toxicity to aquatic algae and cyanobacteria

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Description of key information

The substance was tested for growth inhibition on algae Desmodesmus subspicatus.
The test was performed according to method C.3. - Freshwater Algae and Cyanobacteria, Growth Inhibition Test, Commission Regulation (EC) No. 761/2009, Annex IV.
Since the test substance is multi-component poorly soluble substance the water-accommodated fractions (WAFs) were prepared by adding measured amounts of the test substance to the test medium and then were stirred for a period of 72 hours. After period of stirring the WAFs were filtered through 0.45 μm filter and these solutions were used for testing. The WAFs were prepared for preliminary and main test.
The preliminary test was performed in range of test substance loading rates 10 – 100 mg/L. The highest inhibition of growth rate was 1.7 % and the highest inhibition of yield was 9.4 % in the preliminary test. Therefore the main test was performed in appropriate concentration range. The main test was performed in range of test substance loading rates 62 – 100 mg/L.
The study was performed without the analytical determination of the test substance concentrations. Only the concentrations of metals in the highest loading rate 100 mg/L were analysed in the main test. For all evaluations and results the loading rates of the test substance were used.
Test results:
72 hour - ErL50 > 100 mg/L (loading rate)
72 hour - EyL50 > 100 mg/L (loading rate)
72 hour - NOELRr = 100 mg/L (loading rate)
72 hour - NOELRy = 100 mg/L (loading rate)

Key value for chemical safety assessment

EC50 for freshwater algae:
19.9 mg/L
EC10 or NOEC for freshwater algae:
12 mg/L

Additional information

Since the test substance is multi-component poorly soluble substance the water-accommodated fractions (WAFs) were prepared by adding measured amounts of the test substance to the test medium and then were stirred for a period of 72 hours. After period of stirring the WAFs were filtered through 0.45 μm filter and these solutions were used for testing. The WAFs were prepared for preliminary and full test.

 

The preliminary test was performed in range of test substance loading rates 10 – 100 mg/L. Based on the toxicity of the test substance found in preliminary test, the full test was performed in appropriate loading rates.

The full test was performed in range of test substance loading rates 12 – 90 mg/L.

 

The study was performed without the analytical determination of the test substance concentrations. For the analytical determination of the test substance concentration was not available suitable analytical method.

For all evaluations and results the loading rates of the test substance were used.

 

Test results:

72 hour – ErL50 = 50.5 mg/L       (loading rate)   (95% confidence limit: 47.0 – 54.0 mg/L)

72 hour – EyL50 = 19.9 mg/L       (loading rate)   (95% confidence limit: 18.4 – 21.4 mg/L)

72 hour – NOELRr = 24 mg/L      (loading rate)

72 hour – NOELRy < 12 mg/L      (loading rate)