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Ecotoxicological information

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 3‑Hour EC50 of  230 mg/l. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 25mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:
230 mg/L
EC10 or NOEC for microorganisms:
25 mg/L

Additional information

Introduction.

A study was performed to assess the effect of the test item on the respiration of activated sewage sludge. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (1984) No 209 "Activated Sludge, Respiration Inhibition Test", Method C.11 of Commission Regulation (EC) No. 440/2008 and US EPA Draft Ecological Effects Test Guidelines OPPTS 850.6800.

Methods. 

Activated sewage sludge was exposed to an aqueous solution of the test item at concentrations of 10, 32, 100, 320 and 1000 mg/l for a period of 3 hours at a temperature of 21±1°C with the addition of a synthetic sewage as a respiratory substrate.

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.

Results.

The effect of the test item on the respiration of activated sewage sludge gave a 3‑Hour EC50 of 230 mg/l. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 25 mg/l.

It was considered unnecessary and unrealistic to test at concentrations in excess of 1000 mg/l.

The reference item gave a 3-Hour EC50 value of 6.4 mg/l, 95% confidence limits 4.9 – 8.4 mg/l.