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Description of key information

The 3H-NOEC of the test item to the respiration of activated sludge was 10 mg/L, the EC10 was 24 mg/L, and the EC50 was 269 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
269 mg/L
EC10 or NOEC for microorganisms:
24 mg/L

Additional information

A respiration inhibition test with activated sludge according to OECD guideline n°209 and GLP was carried out with the test item. Test system was activated sludge of the municipal treatment plant of 31137 Hildersheim, Germany. The test was carried out under static conditions and the following nominal concentrations were tested : 10 -32 -100 -320 -1000 mg/L. The respiration rates of the control, reference and test item replicates were measured after a contact time of three hours, and the inhibitory effects of the test and reference items were determined in comparison to the control respiration rates.

All the validity criteria of the OECD Guideline 209 were fulfilled: the mean specific oxygen uptake rate of the control replicates was 20 mg O2/g.h ( validity criterion ≥ 20 mg O2/g.h) and the coefficient of variation was 6.1 % (validity criterion < 30%). The EC50 for the reference substance, copper (II) sulfate pentahydrate, was 97.3 mg/L in the required range 53 - 155 mg/L.

The mean inhibition of respiration for the test item replicates ranged from 4% to 82%. The NOEC of the test item was 10 mg/L, the EC10 was 24 mg/L, the EC50 was 269 mg/L and the EC80 was 922 mg/L.