Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

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
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: 1a: GLP guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

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

Test material

Constituent 1
Chemical structure
Reference substance name:
α,α-Dimethyl-ethyl ester benzeneacetic acid
EC Number:
Cas Number:
Molecular formula:
C12 H16 O2
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:
Total exposure duration:
3 h

Test conditions

Test temperature:
The incubation temperature was controlled at 20.4°C to 21.2°C.
6.9-7.5 after the incubation of the test batches.
Details on test conditions:
- 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

- 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):
3,5-Dichlorophenol in the concentrations of 5, 20 and 30 mg/l

Results and discussion

Effect concentrationsopen allclose all
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
respiration rate
Remarks on result:
other: 27 to 351 mg/l
3 h
Dose descriptor:
Effect conc.:
561 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
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:
The EC50 of the substance to Activated sludge (domestic sewage treatment plant) is in the range >100 mg/l to 1000 mg/l.