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Toxicity to microorganisms

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Description of key information

The effect of the test item on the respiration of activated sewage sludge gave a No Observed Effect Concentration (NOEC) after 3 hours exposure of 125 mg/L (OECD 209).

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
125 mg/L

Additional information

GUIDELINE

A study was performed to assess the effect of the test item on the respiration of activated sewage sludge. The method was designed to be compatible with OECD Guidelines for Testing of Chemicals (2010) No 209 "Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation).

METHODS

Following a preliminary range-finding test and two initial experiments, activated sewage sludge was exposed to an aqueous dispersion of the test item at concentrations of 125, 250 and 500 mg/L (5 replicates of each) for a period of 3 hours at a temperature of approximately 20°C with the addition of a synthetic sewage as a respiratory substrate.

RESULTS

The effect of the test item on the respiration of activated sewage sludge gave a No Observed Effect Concentration (NOEC) after 3 hours exposure of 125 mg/L. The reference item gave a 3 -hour EC50 value of 7.4 mg/L (95 % confidence limits 5.8 -9.5 mg/L).