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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

Activated sludge, acute toxicity test for microorganisms, EC 440/2008 Method C.11 (OECD 209), EC50 (3h) > 1000 mg/L 

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L

Additional information

The acute toxicity to microorganisms of the test substance was investigated according to EC 440/2008 Method C.11, which is equivalent to OECD 209 (Richter, 2011). The study was conducted under GLP. The inoculum was taken from the aeration tank of a domestic sewage treatment plant (Municipal STP Cologne - Stammheim) and was daily fed with synthetic medium. The substance was tested in the concentrations of 10, 100 and 1000 mg/L under flow-through conditions in freshwater. The temperature was held constant at 20 +/- 2°C at the pH range of 6 - 8. The dissolved test medium was mixed with the activated sludge, synthetic medium and deionised water. 3,5 -Dichlorophenol was used as reference substance and prepared in the same way. Two control vessels were prepared as well as vessels to determine the physico-chemical oxygen consumption. For this purpose no activated sludge is added to the mixture. After 3 h incubation time the respiration was inhibited for 32.2 % at a test item concentration of 1000 mg/L. The EC50 value (> 1000 mg/L) is calculated from respiration rates at different test item concentrations using the statistics program ToxRatPro Version 2.10 (released 2010 -02 -20). All validity criteria of the test method were met: the respiratory rates of the 2 controls differ less than 15 % from each other and the EC50 of the reference compound is in the range of 5 -30 mg/L (result: 10 mg/L).