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Toxicity to microorganisms

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Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1988-11-30
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Non GLP study. Deviations from the updated OECD-guideline (adopted 2010). Instead a centrifuged sludge a settled sludge was used. Due to the expected low toxicity of the test substance, the substance was tested at one concentration (100 mg/L) in duplicate samples. The substance was not dissolved but distributed in the test medium. The sludge concentration in the test bottles was 2 g/L instead of 1.4 - 1.8 g/L.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1988
Report date:
1988

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
yes
Remarks:
Settled sludge instead of centrifuged one. The substance was tested at one concentration (100 mg/L) in duplicate samples. The substance was not dissolved, but distributed in the test medium. Sludge concentration was 2 g/L.
GLP compliance:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Didodecyl 3,3'-thiodipropionate
EC Number:
204-614-1
EC Name:
Didodecyl 3,3'-thiodipropionate
Cas Number:
123-28-4
Molecular formula:
C30H58O4S
IUPAC Name:
didodecyl 3,3'-sulfanediyldipropanoate

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: 20.5 rsp. 20 mg of the test substance were weighed and added to the test medium. The volume was adjusted to 200 mL with bidistilled water and aerated for 3 hours.

Test organisms

Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Source: Activated sludge collected from the sewage treatment plant of CH - 4153 Reinach on 28/11/88.
- Pretreatment: according to guideline
- Initial biomass concentration: 2.0 g/L
The sludge was separated from the aqueous layer by settling instead of centrifugation.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
3 h
Post exposure observation period:
None

Test conditions

Test temperature:
20 ± 2 °C
pH:
7.8
Nominal and measured concentrations:
102.5 and 100 mg/L (nominal)
Details on test conditions:
TEST SYSTEM
- Test vessel: BOD flasks with gas inlet
- Type: closed
- Material, size, headspace, fill volume: 250 mL (size)
- Aeration: None
- No. of organisms per vessel: 2 g/L
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): None
- Reference substance: 3,5-Dichlorophenol at 32, 10, and 3.2 mg/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dechlorinated drinking water
- Medium: In accordance to the guideline

OTHER TEST CONDITIONS
- Adjustment of pH: None

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Oxygen consumption per hour in mg/liter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: Single concentration in duplicate
- Justification for using less concentrations than requested by guideline: Expected low toxicity of the test substance
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol

Results and discussion

Effect concentrationsopen allclose all
Duration:
3 h
Dose descriptor:
IC50
Effect conc.:
> 100 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:
other: IC20
Effect conc.:
> 100 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:
other: IC80
Effect conc.:
> 100 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: None
- Effect concentrations exceeding solubility of substance in test medium: None
Results with reference substance (positive control):
- Results with reference substance valid: Yes
- Relevant effect levels: Graphically determined IC50 = 12 mg/L

Any other information on results incl. tables

The inhibitions were calculated on the basis of the measured time dependent oxygen consumption of Blank and Test solutions.

Applicant's summary and conclusion

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