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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

In a study performed according to OECD TG 209, the effect of the test item on the respiration of activated sewage sludge gave a 3-hour EC50 value of > 1000 mg/L. The 3-hour NOEC was 100 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
100 mg/L

Additional information

A study was performed to assess the effect of the test item on respiration of activated sewage sludge. The method followed was designed to be compatible with OECD TG 209.

 

Following a preliminary range-finding test, activated sewage sludge was exposed to an aqueous dispersion of the test item at concentrations of 250, 500, 750 and 1000 mg/L (5 replicates) for a period of 3 hours at temperatures between 20 and 22 deg C with the addition of a synthetic sewage as a respiratory substrate. One extra concentration was added in order to determine the NOEC.

 

The rate of respiration was determined after 3 hours contact time and compared to data for the control and a reference item, 3,5 -dichlorophenol.

 

The effect of the test item on the respiration of activated sewage sludge gave a 3 -hour EC50 value of > 1000 mg/L. During the definitive test a NOEC was not achieved, however during the second range-finding test a NOEC value of 100 mg/L was observed. The reference item gave a 3-hour EC50 value of 6.5 mg/L, confidence limits 5.0-8.5 mg/L.