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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

The toxicity to microorganisms was determined in this OECD guideline and GLP study. The EC50 was determined to be 12.2 mg/L and the EC10 was determined to be 3 mg/L. 

Key value for chemical safety assessment

EC50 for microorganisms:
12.2 mg/L
EC10 or NOEC for microorganisms:
3 mg/L

Additional information

One GLP study is available which assessed the inhibitory effect of the test item on the respiration of activated sewage sludge, carried out according to standard guidelines (OECD 209). The domestic activated sludge (suspended solids 1.6 g/L) was fed with synthetic sewage and was exposed for 3 hours to nominal concentrations of 3, 10, 30, 80, and 240 mg/L. Test mixtures and two controls were treated with an antifoaming agent to suppress excessive foam formation caused by aeration of the test substance. The rate of oxygen consumption was measured, over a period of approximately 10 minutes or until the dissolved oxygen concentration fell below 2 mg O2/L and compared to control and to the reference chemical 3,5 dichlorophenol as positive control. One replicate per treatment and three controls were established, one control containing inoculated medium and antifoam and the other two without added antifoam. Sludge respiration was unaffected by the antifoam used in all test mixtures. The 3h EC50, determined by statistical analysis, was 12.2 mg/L. The EC10 was ~ 3 mg/L, which represent a closer approximation of a NOEC. Results are expressed as nominal concentrations.