Ethanol, 2-[(3-nitropyrazolo[1,5-a]pyridin-2-yl)oxy]-

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From July 2014 to January 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well described study performed according to OECD guideline and GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

Temperature in test vessels 20°C ± 4°C instead of 20°C ± 2°C No impact. See detailed report attached.

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

yes

Remarks:

Same as above.

Test guideline 3

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

Deviations:

yes

Remarks:

Same as above.

GLP compliance:

yes

Remarks:

Certificate available in the attached report.

Test material

Test material information

Constituent 1

Reference substance name:

2-({3-nitropyrazolo[1,5-a]pyridin-2-yl}oxy)ethan-1-ol

EC Number:

938-829-3

Cas Number:

936103-10-5

Molecular formula:

C9H9N3O4

IUPAC Name:

2-({3-nitropyrazolo[1,5-a]pyridin-2-yl}oxy)ethan-1-ol

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Test solutions

Details on test solutions:

Test Concentrations: Nominal 25.6, 64, 160, 400 and 1000 mg test item/L

Test organisms

Test organisms (species):

activated sludge, domestic

Study design

Total exposure duration:

3 h

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Conc. based on:

other: total respiration

Effect concentrations 2

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

ca. 270.9 mg/L

Conc. based on:

other: total respiration

Effect concentrations 3

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Conc. based on:

other: total respiration

Effect concentrations 4

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Conc. based on:

other: Heterotrophic Respiration without Nitrification

Effect concentrations 5

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

ca. 341.1 mg/L

Conc. based on:

other: Heterotrophic Respiration without Nitrification

Effect concentrations 6

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Conc. based on:

other: oxygen uptake due to nitrification

Effect concentrations 7

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

ca. 178.6 mg/L

Conc. based on:

other: oxygen uptake due to nitrification

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

R0056895A had no effects on the respiration of activated sludge microorganisms up to a concentration of 400 mg/L.
The mean respiration rate of activated sludge treated with the test item at concentrations up to 400 mg/L differed from the respiration rate in the control less than 15%. Although the inhibition was 20.7% at the test item concentration of 1000 mg/L, the NOEC could be established to be higher than or equal 1000 mg/L.

Executive summary:

The influence of the test item R0056895A on the activity of activated sludge was evaluated by measuring the respiration rate under defined conditions according to the OECD Guideline for Testing of Chemicals, No. 209: "Activated Sludge, Respiration Inhibition Test", adopted July 22, 2010.

The respiration rate (oxygen consumption) of an aerobic activated sludge fed with a standard amount of synthetic sewage was measured in the presence of various concentrations of the test item after an incubation period of 3 hours. Concentrations of 25.6, 64, 160, 400 and 1000 mg test item/L for R0056895A and concentrations of 1.0, 4 and 16 mg 3,5-Dichlorophenol/L and six inoculum controls were used to determine the inhibition on total respiration and heterotrophic respiration (without nitrification) in a doseresponse

study.

In comparison to the inoculum controls the total respiration rate of the activated sludge was not inhibited at the two lower test concentrations only slightly inhibited for the other test concentrations. The inhibition was 1.0% at a test concentration of 25.6 mg/L and -1.0% at a test item concentration of 64 mg/L. For the test item concentrations of 160 mg/L and 400 mg/L the inhibition rates were 14.5%, and 8.9%, respectively. The highest test concentration of 1000 mg/L resulted in an inhibition of 20.7%. Concentrations

exceeding 1000 mg/L nominal were not tested.

In comparison to the inoculum controls the respiration was not inhibited by the lowest test concentration and only slightly inhibited at the other test concentrations. The inhibition rates were 1.0%, 4.6% and 5.3% at test item concentrations of 25.6 mg/L, 64 mg/L and 160 mg/L, respectively. At the concentrations of 400 mg/L and 1000 mg/L the inhibition of the respiration rate was 14.0% and 14.7%.

In comparison to the inoculum controls, the respiration rates of the activated sludge based on nitrification were only moderately inhibited at the test item concentrations of 160 and 1000 mg/L (25.5% and 27.9% inhibition, respectively). For all other test item concentrations there was no inhibition on nitrifying activated sludge bacteria (inhibition below 3%).

The 3-hour EC50 for total respiration, heterotrophic respiration and oxygen uptake due to nitrification could not be calculated, therefore it can be supposed to be >1000 mg/L. Therefore NOEC calculations were performed. The NOEC is established to be higher than or equal 1000 mg/L.

The positive control 3,5-Dichlorophenol was tested in the same way as the test item. The 3-hour EC50 for total respiration, heterotrophic respiration and for the oxygen uptake due to nitrification was in the range recommended by the test guidelines and confirms the suitability of the activated sludge used.