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Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))
GLP compliance:
yes
Analytical monitoring:
yes
Vehicle:
not specified
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
The test item was tested using 4 concentrations ranging from 1000 to 1 mg/L nominal concentration. Duration of the test was 3 hours. Activated sludge was used as inoculum. It was taken from a domestic sewage treatment plant and washed before usage. The dry matter was determined as 2.14 g suspended solids/L, giving a concentration of 1.07 g suspended solids/L in the test.
Test type:
not specified
Limit test:
yes
Total exposure duration:
3 h
Hardness:
tap water
Test temperature:
22. 1 – 24.7 °C (first experiment (pre-test))
21.7 -24.8 °C (second experiment (main test))
pH:
7.6-7.9
Reference substance (positive control):
yes
Remarks:
1 replicate/concentration (all experiments)
Key result
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
ca. 320 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Key result
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
ca. 630 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
ca. 3 700 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Validity criteria fulfilled:
yes
Conclusions:
3h NOEC = 320 mg/L
3h EC10 = 630 mg/L (confidence interval: 420 – 810 mg/L)
3h EC50 = 3700 mg/L (extrapolated) confidence interval: not determinable

Description of key information

3h NOEC = 320 mg/L

3h EC10 = 630 mg/L (confidence interval: 420 – 810 mg/L)

3h EC50 = 3700 mg/L (extrapolated) confidence interval: not determinable

Key value for chemical safety assessment

EC50 for microorganisms:
3 700 mg/L
EC10 or NOEC for microorganisms:
320 mg/L

Additional information