1-Ethyl-3-methylimidazolium benzoate

Toxicity to aquatic algae and cyanobacteria

Description of key information

In an alga growth inhibition test with Pseudokirchneriella subcapitata according to OECD guideline 201 (BASF SE, 2018), a EC50 of 469 mg/L was determined (EC10 = 144 mg/L).

Key value for chemical safety assessment

EC50 for freshwater algae:

469 mg/L

EC10 or NOEC for freshwater algae:

144 mg/L

Additional information

The toxicity of the test item to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD guideline 201 and Council Regulation (EC) No. 266/2016 method C.3 (BASF SE, 2018). The aim of the study was the determination of EC10-, EC20- and EC50-values of the growth rate over a period of 72 hours.

The test item is yellowish, clear, viscous liquid and miscible with water at room temperature (T = 23 °C) and at T = 20.0 °C ± 0.5 °C in any ratio. The study was conducted under static conditions with an initial cell density of 6839 cells/mL. A stock solution with a nominal concentration of 1000 mg/L was freshly prepared with dilution water and agitated until the solution was visually clear. The stock solution and four dilution levels out of the stock solution were tested in a geometrical series with a dilution factor of √10: 10.0 - 31.6 -100 - 316 - 1000 mg/L. Three replicates were tested for each test item concentration and six replicates for the control. The test media were visually clear throughout the exposure. The environmental conditions were within the acceptable limits. The EC50 -value for inhibition of growth rate after 72 hours was 469 mg/L. The nominal concentrations were confirmed by analytical measurement.