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Ecotoxicological information

Toxicity to aquatic plants other than algae

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Description of key information

EC50 (7d) > 100 mg/l for frond numbers growth rate.

Key value for chemical safety assessment

EC50 for freshwater plants:
100 mg/L
EC10 or NOEC for freshwater plants:
0.25 mg/L

Additional information

Toxicity of test substance to aquatic plants other than algae was assessed in a 7 -day semi-static test on lemna gibba according to OECD guideline 221. The following nominal concentrations of the test item were tested: 0.10, 0.32, 1.0, 3.2, 10, 32 and 100 mg/l along with a control. The test medium renewal occurred on day 2 (duration 48 h), 3 (duration (24 h), 5 (duration 48 h). Mean measured concentrations were calculated as the time weighted means of the concentrations measured at the start and end of the 48 h interval (day 0 - day 2) and the 24 h interval (day 2 - day 3). Biological results were related to mean measured concentrations. In particular, mean measured concentrations were: 0.035, 0.14, 0.51, 2.3, 9.0, 32, 105 mg/l.

The following results were obtained:

EC50 (7d) > 105 mg/l for frond numbers growth rate, dry weight growth rate, frond mortality.

In particular, inhibition of growth rate at 105 mg/l during the 7-day exposure period is 41.7 % and 23.82 % for frond numbers and dry weight, respectively.

EC10 (7d) = 0.25 mg/l for frond numbers growth rate, 2.8 mg/l for dry weight growth rate, > 105 mg/l for frond mortality.

NOEC (7d) = 0.035 mg/l for frond numbers growth rate, 0.51 mg/l for dry weight growth rate, 105 mg/l for frond mortality.

ECx concentrations were calculated by Probit analysis; NOEC and LOEC values were calculated by Willams t-test or Welch t-test.

By following a precautionary approach, an EC50(7d) = 100 mg/l is used in the chemical safety assessment.