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Ecotoxicological information

Toxicity to aquatic plants other than algae

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Description of key information

In a static toxicity key study (Institute of Industrial Organic Chemistry, 708271, 2014) with Lemna gibba the 7 d-NOEC was determined to be 2.01 mg/L and the 7d-ErC50 was determined to be 26.20 mg/L.

Key value for chemical safety assessment

EC50 for freshwater plants:
26.2 mg/L
EC10 or NOEC for freshwater plants:
2.01 mg/L

Additional information

In a 7-day static toxicity laboratory key study (Institute of Industrial Organic Chemistry, 708271, 2014) the effect of the test substance on growth of freshwater aquatic plant Lemna gibba was investigated. The primary objective of the test was to estimate 7day median effect concentration (EC50) values for Lemna gibba exposed to the test substance. The plants were exposed to concentrations of 2.010, 4.038, 8.909, 17.207, 39.090 mg/L (initial measured test item concentrations) and the control, with four replicates for each test item concentration and eight for control. The nominal concentrations of the test substance were 2-fold, 4-fold, 8-fold and 16 fold diluted centrifuged solution of the loading of 100 mg/L. The control consisted of test medium only. Number of fronds in each test vessel was counted and changes in plant development were observed on days 3, 5 and after 7 days of exposure. Dry weight of each control and test substance treatment replicate was assessed at test termination. The inhibition of growth rate and the inhibition of yield were estimated in comparison to the control based on frond number and based on dry weight after 7 days of exposure. The biological results are based on the initial measured and geometric mean of the determined test item concentrations. At exposure termination, in the initial measured test item concentrations of 2.010 and 4.038 mg/L no distinctive changes from the normal development of plants in the control were observed. In the initial measured test item concentration of 8.909 mg/L, smaller young fronds, spots of chlorosis, bending down of colonies and shorter roots were observed. In the initial measured test item concentrations of 17.207 and 35.090 mg/L, spots of chlorosis, smaller young fronds and shorter roots were observed. Moreover, in the initial measured test item concentration of 35.090 mg/L, breaking-up of colonies were observed. After 7 days of exposure, the ErC50 of the reference item was determined to be 9.99 mg/L (based on frond number) and the EyC50 was determined to be 8.55 mg/L (based on frond number). The validity criteria were met. The 7 d-NOEC was determined to be 2.01 mg/L and the 7d-ErC50 was determined to be 26.20 mg/L. These values were based on the growth rate of the frond number.