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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The 72-hour EC50 for inhibition of growth rate (ErC50) was 2.13 mg/L, the 72-hour EC10 for inhibition of growth rate (ErC10) was 1.68 mg/L. The 72-hour NOEC for inhibition of growth rate was < 0.473 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
2.13 mg/L
EC10 or NOEC for freshwater algae:
1.68 mg/L

Additional information

The toxicity of test item to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 266/2016, C.3.

The study was conducted under static conditions in closed bottles without headspace over a period of 72 hours. Based on preliminary range finding tests, the saturated solution and four dilution levels of the saturated solution were tested in a geometrical series with a dilution factor of 3.2: 1:100 -1:32 - 1:10 -1:3.2 and the undiluted saturated solution.

The measured initial concentrations of test item were 0.603 - 1.59 - 6.37 - 18.4 - 49.1 mg/L and reflect the dilution factor of 3.2. The measured concentrations of test item in the old media (72 h) containing algae were in the range of 62 to 79% of the initially measured values. These results led to the geometric mean measured test item concentrations 0.473 - 1.39 - 5.29 -15.0 - 43.7 mg/L, which all effects were based on.

In this study, test item was found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours with the following effect values (based on geometric mean measured test item concentrations): The 72-hour EC50-value with 95 % confidence intervals for inhibition of growth rate (ErC50) was 2.13 (1.47 - 4.13) mg/L. The 72-hour EC10-value with 95 % confidence intervals for inhibition of growth rate (ErC10) was 1.68 (1.40 - 3.89) mg/L. The 72-hour NOEC for inhibition of growth rate was < 0.473 mg/L.