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Ecotoxicological information

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)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Activated sludge from laboratory wastewater plant treating municipal sewage.
- The inoculum was washed, brought to a concentration of 5 g/L dry substance and aerated during the night.
- 50 mL were added to a total volume of 250 mL to obtain a concentration of 1 g/L dry substance in the test.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
30 min
Test temperature:
20+/-2°C
Dissolved oxygen:
- During aeration: >2.5 mg/L
- Immediately before measurement: >6.5 mg/L
Nominal and measured concentrations:
- Nominal concentrations of test substance (mg/L): 10, 100, 248, 496, 1000
Details on test conditions:
- Test vessels: Erlenmeyer-vessels (nominal volume 250 mL)
- Test volume: 250 mL
- Synthetic medium: 8 mL/vessel 100-fold concentrated OECD
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol
Duration:
30 min
Dose descriptor:
other: EC20
Effect conc.:
ca. 170 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Key result
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
ca. 550 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
30 min
Dose descriptor:
other: EC80
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Results with reference substance (positive control):
- EC50 of 3,5-dichlorophenol in the range of 5-30 mg/L
- Deviation of blank controls < 15%

Description of key information

The test substance was tested in an OECD guideline study. The EC50 was determined to be 550 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
550 mg/L

Additional information

Freshwater

Key

The test substance was tested in an OECD guideline 209 study. The nominal concentrations tested were 10, 100, 248, 496, 1000 mg/L.The test was conducted under static conditions. Domestic activated sludge was used as inoculum. The total exposure duration was 30 min. The EC50 was determined to be 550 mg/L.

Supporting

The toxicity to microorganisms was tested in a study according to DIN 38412-8. The nominal concentration (mg/L) used were: 39.06, 78.13, 156.25, 312.5, 625, 1250, 2500, 5000, 10000. The EC50 value was determined to be 55.4 mg/L and the EC10 value was determined to be 41.3 mg/L. Both values based on growth inhibition.

The toxicity to microorganisms was tested in this OECD guideline study. The test substance was tested under static conditions with a total exposure duration of 30 min. The EC50 value was determined to be 560 mg/l.

The toxicity to microorganisms was tested in this OECD guideline study. Only few data were available for this study. The EC50 value was determined to be 370 mg/L and the EC10 value was determined to be 140 mg/L.

Conclusion: 4 different studies were available. 3 OECD guideline studies were available one study according to DIN 38412 -8. The results of the guideline studies lay all in the same range. As a result the EC50 value of 550 mg/L was chosen as key result.