1H,5H-Pyrazolo(1,2-a)pyrazol-1-one, 2,3-diamino-6,7-dihydro-, dimethanesulfonate

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20 September 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: compliant to GLP and testing guideline; adequate coherence between data, comments and conclusions

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

Deviations:

no

GLP compliance:

yes

Test material

Reference

Name:

Unnamed

Type:

Constituent

Details on test material:

- Name of test material (as cited in study report): R0054002C, synonym IMEXINE OBH
- Physical state: beige to yellow powder
- Purity: 99.7%
- Impurities (identity and concentrations): not indicated
- Purity test date: 20 July 2006
- Lot/batch No.: R0054002C 013 L 001, synonym 0604070001
- Expiration date of the lot/batch: 01 August 2007
- Stability under test conditions: not indicated
- Storage condition of test material: at room temperature and under nitrogen gas

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Origin: the water treatment plant of Evreux (France)
- Preparation of inoculum for exposure: after sampling, the inoculum was left to settle and the main part of the supernatant was rejected.
As the sludge was used the next day, 50 mL of sewage feed were added, per liter, and it was then agitated and aerated until use.
- Pretreatment: no
- Initial biomass concentration: 4 g/L

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

Oxygen concentration was determined for a period of approximately 10 minutes

Test conditions

Hardness:

280 ± 20 mg/L as CaCO3

Test temperature:

between 21 and 23°C

pH:

between 6.0 and 8.0

Dissolved oxygen:

air was bubbled through each suspension at the rate of 0.5 to 1 L/min until the start of oxygen concentration measurements

Salinity:

Not measured

Nominal and measured concentrations:

10, 31.6, 100, 316 and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type: open
- Material, size, headspace, fill volume: glass, 500 mL of solution
- Aeration: 0.5 to 1 liter of air per minute using a Pasteur-pipette connected with a flexible tube to an air pump as an aeration device
- No. of vessels per concentration (replicates): one
- No. of vessels per control (replicates): two
- Biomass loading rate: 1.6 g/L


TEST MEDIUM
- Source/preparation of dilution water: dechlorinated tap water


OTHER TEST CONDITIONS
- Adjustment of pH: none
- Light intensity: no special precautions were taken


EFFECT PARAMETERS MEASURED: respiration rate was determined from the recorder trace in terms of mg O2/L/h

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

3 h

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 2

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

316 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

Inhibitions of the respiration rate in the test item suspensions was 6 % at 10, 31.6, 100 and 316 mg/L and 29% at 1000 mg/L, relative to mean of the controls

Results with reference substance (positive control):

EC50 3 h (3,5-dichlorophenol) =13.6 mg/L

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The 3-hour EC50 of the test item IMEXINE OBH for activated sludge respiration inhibition was > 1000 mg/L. The highest test item concentration without significant effect on the respiration was 316 mg/L.