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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
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
- Name of test material (as cited in study report): C-SAT 090069
- Physical state: amber coloured viscous liquid
- Analytical purity: > 89%
- Lot/batch No.: C-081
- Expiration date of the lot/batch: 26.02.2013
- Storage condition of test material: room temperature
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test substance was directly weighed into the incubation vessels.
Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Laboratory culture: fresh sample of activated sludge taken from the aeration basin of a municipal sewage treatment plant (Moers, Germany)
- Preparation of inoculum for exposure: Activated sludge was filtered by means of a water jet pump through a filter paper. The sludge was washed twice with mineral medium. Afterwards, 4g/L activated sludge was suspended in mineral medium, 50 mL synthetic sewage were added and the whole mixture was stirred and aerated overnight at 20 °C.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Test temperature:
20 ±2 °C
pH:
7.61 - 8.37
Nominal and measured concentrations:
Nominal: 10, 32, 100, 320 and 1000 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 1 L beakers (incubation) and 300 mL Karlsruher flasks (O2 measurement)
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline

EFFECT PARAMETERS MEASURED: Oxygen consumption was followed after the 3h incubation period by continuous measurement of the oxygen concentration with an oxygen electrode for up to 10 min.
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol
Key result
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
200.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
EC50
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:
- Effect concentrations exceeding solubility of substance in test medium: Test substance was directly weighed into vessels because of its negligible water solubility.
Results with reference substance (positive control):
- Results with reference substance valid? Yes
Validity criteria fulfilled:
yes
Conclusions:
In a GLP study according to OECD guideline 209, the 3h-EC50 of the test substance is > 1000 mg/L, while the respective EC10 is determined to be 200.4 mg/L.
Executive summary:

The toxicity of the test substance to microorganisms was evaluated in a study according to OECD guideline 209 under GLP conditions.

In a static study domestic activated sludge was exposed for 3h. The test material was applied directly to the test vessels. Analytical monitoring was not performed. All validity criteria were fulfilled. The EC50 is determined to be > 1000 mg/L, while the respective EC10 is determined to be 200.4 mg/L based on nominal concentrations.

Description of key information

EC50 (3h) > 1000 mg/L, EC10 (3h) = 200.4 mg/L (nominal) for activated sludge (OECD 209)

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
200.4 mg/L

Additional information

One study investigating the toxicity of the test substance to aquatic microorganisms is available. The study was performed according to OECD guideline 209 under GLP conditions using domestic activated sludge as inocculum (Wehrhahn 2010). The test material was applied directly to the test vessels. Analytical monitoring was not performed. All validity criteria were fulfilled. The EC50 is determined to be > 1000 mg/L, while the respective EC10 is determined to be 200.4 mg/L based on nominal concentrations.