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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
Remarks:
GLP and Guideline compliant study with good documentation
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test item was be weighed out directly in an Erlenmeyer flask and filled up with 100 mL demineralised water. Respective amounts were directly weighed into each test vessel.
- Controls:Test medium without test or reference item
Test organisms (species):
activated sludge of a predominantly domestic sewage
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
3 h
Test temperature:
20.4
pH:
7.29
Nominal and measured concentrations:
1000 mg/L (nominal)
Details on test conditions:
TEST SYSTEM
- Test vessel: 500 mL Erlenmeyer flasks, DIN 12380
- Type (delete if not applicable): open / closed
- Material, size, headspace, fill volume: material: glass; fill voulume: 300 mL
- Aeration: Shaking of flasks at 125 rpm to keep the dissolved oxygen concentration above 60 - 70 % saturation and to maintain the sludge flakes in suspension.
- No. of organisms per vessel: 1.51 g/L dry sludge in test solution
- No. of vessels per concentration (replicates): Triplicates
- No. of vessels per control (replicates): Triplicates
- Biomass loading rate: 1.51 g/L dry sludge in test solution

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Synthetic waste water according to OECD-Guideline 209

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: not provided
- Light intensity: not provided

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : respiration

TEST CONCENTRATIONS
- Spacing factor for test concentrations: NA (limit test)
- Justification for using less concentrations than requested by guideline: limit test
- Range finding study
- Test concentrations: 10, 100 and 1000 mg/L
- Results used to determine the conditions for the definitive study: NOEC at 1000 mg/L
Reference substance (positive control):
yes
Remarks:
copper (II) sulphate pentahydrate
Key result
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
>= 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:
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: not reported
- Effect concentrations exceeding solubility of substance in test medium: no
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- Relevant effect levels: EC50 95.9 mg/L, historical data 53-155 mg/L
- Other: none
Reported statistics and error estimates:
The NOEC was determined by calculation of statistical significance of the inhibition of respiration in comparison to the control. One Way Analysis of Variance (ANOVA) and DUNNETT’s test, if necessary, were used for NOEC calculation. When running a One Way Analysis of Variance a Normality test and an Equal Variance test were done first. P-value for both tests was 0.05. The alpha-value (acceptable probability of incorrectly concluding that there is a difference) is alpha=0.05.
Validity criteria fulfilled:
yes
Conclusions:
NOEC >= 1000 mg/L
Executive summary:

In the klimisch 1 GLP study from Fiebig (2013) the respiration inhibition of Sodium dicyclohexyl sulfosuccinate on activatred municipal sludge was determined according to OECD 209. Based on the outcome of a pre-test, the test was performed as limit test with a control and a test concentration of 1000 mg/L. The test groups were set up in triplicate. All validity parameters as outlined in the OECD 209 were fulfilled. Statistical evaluation showed that the test item had no inhibitory effect on the respiration of the activated sludge at 1000 mg/L. Therefore, the NOEC was determined to be >= 1000 mg/L.

The results of this study are considered relevant and reliable for the risk assessment.

Description of key information

NOEC >= 1000 mg/L

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
1 000 mg/L

Additional information

In the klimisch 1 GLP study from Fiebig (2013) the respiration inhibition of Sodium dicyclohexyl sulfosuccinate on activatred municipal sludge was determined according to OECD 209. Based on the outcome of a pre-test, the test was performed as limit test with a control and a test concentration of 1000 mg/L. The test groups were set up in triplicate. All validity parameters as outlined in the OECD 209 were fulfilled. Statistical evaluation showed that the test item had no inhibitory effect on the respiration of the activated sludge at 1000 mg/L. Therefore, the NOEC was determined to be >= 1000 mg/L.

The results of this study are considered relevant and reliable for the risk assessment.