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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

ErC50 > 100 mg a.i./L (Pseudokirchneriella subcapitata)

ErC10 = 27 mg a.i./L (Pseudokirchneriella subcapitata)

Key value for chemical safety assessment

Additional information

The toxicity towards freshwater algae was determined in a study according to OECD TG 201 and in compliance with GLP criteria (Ibacon, 2017). In this study, exponentially growing freshwater algae (Pseudokirchneriella subcapitata) were exposed to nominal test substance concentrations of 0 (control), 1.3, 4.2, 13.3, 42.1 and 133 mg test item/L for 72 hours under static conditions. The test material as such exists as aqueous solution. The test material concentration corresponds to a nominal concentration of 1, 3.2, 10, 31.6 and 100 mg/L based on active ingredient (a.i.). Test concentrations were analytically verified and determined to be <LOD, 1.3155, 4.6675, 15.6875, 44.389 and 143.4535 mg test material/L (mean measured). All measured test concentrations remained within ± 20% of nominal concentrations throughout the test. Therefore, effect concentrations are expressed as nominal. At the start of the test and after 24, 48 and 72 hours exposure duration, the algae were scored for number of cells and for microscopic abnormalities. At concentrations of nominal 31.6 and 100 mg a.i./L, significant inhibition in yield and growth rate was observed after 48 hours. After 72 hours exposure, yield was inhibited for 49.2% and 86.4% and growth rate was inhibited for 13% and 38.1% at test concentrations of 31.6 and 100 mg a.i./L, respectively. Cells also showed deformations at these concentrations. Based on these findings, the 72-h EC50 values for growth rate and yield are determined at > 100 mg a.i./L and 34.2 mg a.i./L, respectively. The 72-h EC10 values for growth rate and yield are determined at 27 mg a.i./L and 11.5 mg a.i./L.