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Ecotoxicological information

Toxicity to aquatic plants other than algae

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Description of key information

ErC50 (Lemna minor, frond numbe and dry mass, 7 d): >  28.13 mg/L (geom. mean of measured concentrations corresponding to nominal concentration of 100 mg/L).

Key value for chemical safety assessment

Additional information

The acute toxicity of the test item to aquatic plants was investigated in a 7–day static test to Lemna minor, according to the OECD Guideline 221 (2006). The study was performed using 5 concentrations ranging from 4.6 to 100 mg/L (nominal concentration). The frond number of each replicate was determined at the beginning, at day 3 and 6 during the test and at the end of the experiment. Additionally, the dry mass of each replicate was determined at the beginning and at the end of the experiment. Growth rate µ and the yield were determined from the frond number and the dry mass at the respective observation times.

Plant growth at 4.6 mg/L was biased because these replicates were contaminated. Therefore, this concentration was not used for evaluation. Despite the lack of this treatment, the results can be considered reliable because toxicity was observed only in the highest concentrated treatment.

At the start and at the end of the test, the content of the test item in the test solutions was determined using photometer.

In the treatments 10 – 100 mg/L, the measured concentrations lay between 35 % and 39 % of the nominal concentrations at the beginning of the test and between 15 % and 21 % of the nominal concentrations at the end of the test.Therefore, the determination of the NOEC / LOEC / ECx was based on the geometric mean of the measured concentrations.

No turbidity of the solution occurred either at the beginning or at the end of the test. The reduction of the test item content can be explained by the adsorption of the test item onto the plants. During validation, the test item was stable in test medium without plants.