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Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Start of experimental part: 06.08.1997 / End of experimental part: 06.08.1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: 1a: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report date:
1997

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Qualifier:
according to guideline
Guideline:
ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
α,α-Dimethyl-ethyl ester benzeneacetic acid
EC Number:
608-307-7
Cas Number:
2901-13-5
Molecular formula:
C12 H16 O2
IUPAC Name:
α,α-Dimethyl-ethyl ester benzeneacetic acid
Details on test material:
Name: Ethyl dimethylphenylacetate
Synonyms: EDMPA
Chemical name: Benzeneacetic acid, α,α-dimethyl-, ethyl ester
Code: HOE CG 0523 0Y ZD00 0001
Certificate of analysis: March 18, 1997
Purity: 99.8%
Appearance: clear, colorless liquid
Solubility: 0.3 g/L in water
Batch number: B 0006
Date of production: March 12, 1997
Date of expiry: March 18, 2000

Test organisms

Test organisms (species):
activated sludge, domestic
Details on inoculum:
Origin: Sewage treatment plant at Frankfurt am Main-Sindlingen
Type of inoculum: Domestic activated sludge
Preparation of the suspension: sediment from activated sewage sludge was washed three times by centrifuging and resuspending in water with 0.9 %NaCl.
Amount used: 450 ml/l sludge suspension
Content of suspended solids: 27.78 g/l (centrifuged wet matter)
Content of suspended solids: 3.56 g/l (dry matter)
Content in the final test volume: 1.6 g/l (dry matter)
Pretreatment: corresponding to the cited test guideline.
State of acclimatization: not pre-adapted to the test substance or the reference substance.
Storage: The concentrated inoculum suspension was aerated over 2 days. Nutrition solution was added during this period.

Study design

Water media type:
freshwater
Total exposure duration:
3 h

Test conditions

Test temperature:
The incubation temperature was controlled at 20.4°C to 21.2°C.
pH:
6.9-7.5 after the incubation of the test batches.
Details on test conditions:
TEST SYSTEM
- Test vessel: Glasbottles with a diameter of 60 mm and a grounded neck (NS 29), height 170 mm and a total volume of approx. 480 ml.
- Test volume: 200 ml
- Aeration/test vessel: 50L/hour only during the incubation period

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Justification for test concentrations: Due to the low solubility no stock solution was prepared. The test material was weighed out directly into the test vessels.
Highest concentration tested: 1000 mg/l, lowest concentration tested: 62.5 mg/l
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol in the concentrations of 5, 20 and 30 mg/l

Results and discussion

Effect concentrationsopen allclose all
Duration:
3 h
Dose descriptor:
other: EC20
Effect conc.:
186 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: 27 to 351 mg/l
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
561 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: 295 to 3342 mg/l
Results with reference substance (positive control):
Testing the respiration inhibition of activated sludge proceeded without disturbances. The EC50 of the reference substance 3,5-Dichlorophenol was between 5 mg/L and 30 mg/L and amounted to 10 mg/L.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The EC50 of the substance to Activated sludge (domestic sewage treatment plant) is in the range >100 mg/l to 1000 mg/l.

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