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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The EC50 for growth rate of Pseudokirchneriella subcapitata at 0–72 h was 8.7–9.19 mg/L. The NOEC for growth rate was 0.22–1.97 mg/L and the EC10 0.17–3.11 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
8.7 mg/L
EC10 or NOEC for freshwater algae:
0.22 mg/L

Additional information

The batch of Adipic acid dihydrazide tested was a white powder with a purity of 99% and the substance was completely soluble in test medium at the concentrations tested.

A final test was performed based on the results of a combined limit/range-finding test. Six exponentially growing algal cultures were exposed to an untreated control, whereas three replicates per group were exposed to 0.32, 1.0, 3.2, 10, 32 and 100 mg Adipic acid dihydrazide per litre. Initial cell density was 104 cells/ml. The total exposure period was 72 hours and samples for analytical

confirmation of exposure concentrations were taken at the start, after 24 and 72 hours of exposure.

The actual concentrations were at the level of nominal (91-98%) at the start of the test. Measured concentrations decreased to 26-73% of initial at the end of the test. The Time Weight Average (TWA) concentrations were calculated to correspond to 0.22, 0.62, 1.7, 5.5, 21 and 81 mg/l at nominally 0.32, 1.0, 3.2, 10, 32 and 100 mg/l, respectively.

The EC50 for growth rate of Pseudokirchneriella subcapitata at 0-72 h was 8.7 - 9.19 mg/L. The NOEC for growth rate was 0.22 - 1.97 mg/L and the EC10 0.17- 3.11 mg/L.

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