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Toxicity to aquatic algae and cyanobacteria

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Description of key information

No effects were observed and thus the NOEC was considered to be equal to the maximum water solubility in medium and the 72h-EC50 was considered to exceed the maximum solubility of the test substance in medium.

Key value for chemical safety assessment

Additional information

The toxicity to Pseudokirchneriella subcapitata was examined under static conditions in a test that was carried out according to OECD 201 and GLP.

The test was carried out as a limit test with a nominal concentration of 100 mg/L. The test substance and dilution water were mixed and they were stirred by magnetic stirrer for about 48h at 20°C to prepare 100 mg/L (nominal concentration). Then, the test medium was filtrated with glass fiber filter (diameter 0.4 µm). The filtrate was also filtered by suction filtration with a membrane filter (diameter 0.22 µm). The concentration of the test substance was measured at t = 0, 24, 48 and 72 h. At the start a separate solution sampled from the container for preparation was used for analysis. At the end, samples were taken out of from the middle layer from each test vessel and mixed. Samples were analysed by HPLC-UV.

The test solution of the present test was clear and colourless, whereas in the test with fish and daphnia that were also carried out with a loading rate of 100 mg/L a yellow colour and undissolved substance was observed. A possible explanation is the filtration step with the 0.22 µm filter.

The measured concentration was 0.010 mg/L at the start and below the detection limit (0.0087 mg/L) at t = 24, 48 and 72h. The measured TWA concentration calculated by reviewer (using 0.5*LOD = 0.00435 mg/L as measured concentration at t = 24, 48 and 72 h) = 0.0051 mg/L.

No effects were observed and thus the NOEC was considered to be equal to the maximum water solubility in medium and the 72h-EC50 was considered to exceed the maximum solubility of the test substance in medium.

The validity criteria were fulfilled.

The study is considered reliable without restriction