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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 (incl. certificate)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 239930
- Analytical purity: 93.9 g/100 g; w(C6H11) = 25.4 g/100 g; w(C3H60) = 68.5 g/100 g

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Medium: 8 ml synthetic medium 50 ml inoculum, filled up with dionised water to a total volume of 250 ml.
Test organisms (species):
activated sludge, domestic
Details on inoculum:
Activated sludge from laboratory wastewater plant treating municipal sewage.
- Initial biomass concentration: dry substance: 1 g/l
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
30 min
Test temperature:
20 ± 2 °C
pH:
before correction: 6.7 - 6.8
after correction: 7.2 - 7.7
Nominal and measured concentrations:
Nominal test concentrations (mg/l): 10, 100, 248, 496, 1000
Details on test conditions:
Type: aquatic
TEST SYSTEM
- Test vessel: Erlenmeyer vessel (250 ml)
- Fill volume: 250 ml
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 3

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: 8 ml/vessel 1 00-fold concentrated OECD

OTHER TEST CONDITIONS
- Adjustment of pH: yes

Reference substance (positive control):
yes
Remarks:
3,5 dichlorphenole
Duration:
30 min
Dose descriptor:
other: EC20
Effect conc.:
ca. 130 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
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
ca. 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
Since TS 5 (10 mg/l) delivered no feasible value, if was not considered to determine the EC20 value.

Test item

respiration

% of blank

[mg/L]

[mg O2/g TS]

 

Blank

20

-

10

15

75

100

17

85

248

13

65

496

13

65

1000

10

50

Conclusions:
No inhibition was observed at nominal concentrations up to 1000 mg/L. The EC50 (30 min) value was determined to be ca. 1000 mg/L for activated sewage sludge.

Description of key information

EC50 (30 min) = ca. 1000 mg/L for activated sewage sludge (OECD Guideline 209)

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L

Additional information

The Klimisch 1 study by BASF AG (2003) performed a test at concentrations of 10, 100, 248, 496 and 1000 mg/L. Activated sewage sludge from laboratory wastewater plant treating municipal sewage was used in the study. The rate of respiration was determined after 30 minutes contact time. No inhibition was observed at nominal concentrations up to 1000 mg/L.