Ethyl difluoroacetate

Toxicity to microorganisms

Administrative data

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:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Ethyl difluoroacetate

EC Number:

207-223-4

EC Name:

Ethyl difluoroacetate

Cas Number:

454-31-9

Molecular formula:

C4H6F2O2

IUPAC Name:

ethyl difluoroacetate

Details on test material:

- Name of test material (as cited in study report): Ethyl difluoroacetate
- Physical state: Liquid /colourless, clear
- Analytical purity: 99.9%
- Batch No.: 33244/106 A
- Storage condition of test material: Storage in a refrigerator; avoid temperatures >70 °C

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: 2.0 g of the test substance was added to about 800 mL of demineralized water and stirred at room temperature until the test substance was completely dissolved. The pH-value was measured adjusted to 7.1 with 1 M sodium hydroxide solution. Finally the stock solution was made up to 1 L with demineralized water. The stock solution appeared clear.

Test organisms

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Preparation of inoculum for exposure: The activated sludge suspension was washed 3 times with tap water and sieved with a fine woven mesh (mesh size about 1 mm). This suspension was adjusted to a concentration of 7.5 g/L dry weight and pre-aerated over night. After the pre-aeration the lost water of the suspension was replaced
- Initial biomass concentration: 1.5 g/L dry substance

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

180 min

Test conditions

Test temperature:

22± 2 °C

pH:

7.2 - 7.3

Nominal and measured concentrations:

Nominal test concentrations: 62.4, 125, 250, 500, 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer-vessel (nominal volume 250 ml)
- Test volume: 250 ml
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- No. of vessels per reference substance concentration (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: 8 mL/vessel 100-fold concentrated OECD medium

EFFECT PARAMETERS MEASURED: respiration rate after 180 min

Reference substance (positive control):

yes

Remarks:

3,5 dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

180 min

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 2

Duration:

180 min

Dose descriptor:

other: EC20

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 3

Duration:

180 min

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

Effect concentrations 4

Duration:

180 min

Dose descriptor:

other: EC80

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

EC20 (180 min) = 1.0 mg/L
EC50 (180 min) = 7.0 mg/L
EC80 (180 min) = 47.8 mg/L