3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2007-08-24 to 2007-08-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
- Test substance: 2.0 g of the test substance were added to about 800 mL of demineralized water and stirred at room temperature until the test substance was completely dissolved. After that the pH-value was measured (measured value = 2.8) and adjusted to 7.5 with 1 Mol sodium hydroxide solution. Finally the stock solution was made up to 1L with demineralized water. The stock solution appeared yellowish.
- Reference substance: 0.5 g of the reference substance were added to about 800 mL of demineralized water and stirred at room temperature until the reference substance was completely dissolved. The pH value of the stock solution was measured and adjusted to 7.4 with 1 Mol sodium hydroxide solution. Following this the stock solution was made up to 1L with demineralized water. The stock solution appeared colourless-clear.
- Evidence of undissolved material: None

Test organisms

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Source and Preparation of inoculum for exposure: Activated sludge from the municipal wastewater treatment plant of Mannheim/Baden Württemberg, Germany was collected on 29 August 2007 from the aeration tank of the plant. 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. An aliquot of this suspension was added to the test vessels to obtain a sludge concentration of 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:

Adjusted to pH 7.5

Dissolved oxygen:

Oxygen concentration during aeration: > 2.5 mg/l
Oxygen concentration immediately before measurement: > 6.5 mg/l

Nominal and measured concentrations:

Nominal: 1000, 500, 250, 125 and 62.5 mg/L

Details on test conditions:

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

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

Reference substance (positive control):

no

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