Benzeneacetic acid, .alpha.,.alpha.-dimethyl-, ethyl ester

Toxicity to microorganisms

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 guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Test guideline 2

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

Test material information

Constituent 1

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 concentrations

Effect concentrations 1

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

Effect concentrations 2

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.