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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The acute toxicity of 3-hydroxy-1,1-dimethylbutyl 2-ethyl-2-methylheptaneperoxoate was evaluated with Pseudokirchneriella subcapitata in a study performed in accordance with OECD testing guideline 201 and GLP requirements.

Key value for chemical safety assessment

EC50 for freshwater algae:
9.13 mg/L
EC10 or NOEC for freshwater algae:
0.496 mg/L

Additional information

Triplicate algal cultures were exposed for 72 hours to 3-hydroxy-1,1-dimethylbutyl 2-ethyl-2-methylheptaneperoxoate dissolved in algal nutrient medium at nominal concentrations of 0.1, 0.32, 1.02, 3.28 and 10.5 mg/L. The test media were prepared in algal nutrient medium from an aqueous stock solution, which was made by the direct addition of the test substance to the dilution medium.

Since it was not possible to develop a method of analysis with sufficient sensitivity to verify all exposure concentrations employed during the study, samples were only taken for analysis at the two highest test levels (3.28 and 10.5 mg/L) during the study.

At the start of the test, the measured levels in samples of the test cultures at 3.28 and 10.5 mg/L were 82% and 83% of their nominal values, respectively. After 72 hours, the measured levels had decreased, to less than the limit of detection of the analytical method (1 mg/L) at 3.28 mg/L and 21% of the nominal at 10.5 mg/L. To enable the test results to be expressed in terms of the initial measured concentrations, the concentrations at 0.1 to 1.02 mg/L have been calculated assuming 82.5% of their nominal values were present, giving calculated 3-hydroxy-1,1-dimethylbutyl 2-ethyl-2-methylheptaneperoxoate concentrations of 0.0825, 0.264, and 0.842 mg/L. At 3.28 and 10.5 mg/L, the initial measured levels were 2.70 and 8.75 mg/L respectively.