1H-Pyrazolo[3,4-b]pyridine-3-carboximidamide, 5-fluoro-1-[(2-fluorophenyl)methyl]-

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10 Apr - 29 May 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

[amino({5-fluoro-1-[(2-fluorophenyl)methyl]-1H-pyrazolo[3,4-b]pyridin-3-yl})methylidene]azanium chloride

EC Number:

811-931-4

Cas Number:

1350653-27-8

Molecular formula:

C14 H12 Cl F2 N5

IUPAC Name:

[amino({5-fluoro-1-[(2-fluorophenyl)methyl]-1H-pyrazolo[3,4-b]pyridin-3-yl})methylidene]azanium chloride

Test material form:

solid

Study design

Oxygen conditions:

aerobic/anaerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Species/Origin:
Aerobic activated sludge, microorganisms from a domestic waste water treatment plant was supplied by the sewage treatment plant Rossdorf, Germany.
Conditioning:
The aerobic activated sludge used for this study was deposited for 15 min, washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in test water and centrifuged again. This procedure was done three times. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 3.5 g dry material per litre were mixed with test water (see 6.5) and aerated overnight. This suspension was used for the experiment.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

ca. 100 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Type and Size:
Manometric Test System with test flasks containing a volume of approximately 500 mL.
Apparatus:
BSB/BOD-Sensor-System
Principle:
The test flasks prepared according paragraph 6.6 were incubated at 22°C * 1°C. The pressure decrease in the reaction vessels was measured over complete experimental phase of 28 days using the BSB/BOD-Sensor-System. The test flasks were closed gas-tight by a measuring head. Potassium hydroxide solution (45%) was used for trapping the produced carbon dioxide. The amount of O2 consumed by the activated sludge was calculated from the decrease of pressure in the reaction vessel.
Identification:
Each test unit was uniquely identified with the study number, treatment and replicate number.
Surrounding Type:
Climatised chamber
Temperature:
22°C ± 1°C
Light Conditions:
Darkness
pH-Value of Test Solutions:
7.6 (measured at the start of the test)
7.4 to 7.6 (measured at the end of the test)
Recording:
Test conditions (temperature) were recorded continuously with suitable instruments, documented in the raw data and reported in the final report. (Short-term deviations (< 2 hours) from the recommended temperature range do normally not result in major disturbances of the test performance and were not reported.)
Reconstituted Test Water:
Analytical grade salts were added to pure water to prepare the following stock solutions:
a) 8.5 g KH2PO4, 21.75 g K2HPO4, 33.4 g Na2HPO4 x 2 H2O, 0.5 g NH4Cl filled up with pure water to 1000 mL volume; The pH-value was 7.4.
b) 11.25 g MgSO4 x 7 H2O filled up with pure water to 500 mL volume
c) 18.2 g CaCl2 x 2 H2O filled up with pure water to 500 mL volume
d) 0.125 g FeCl3 x 6 H2O filled up with pure water to 500 mL volume
In order to avoid precipitation of iron hydroxide in the stock solution d), one drop of concentrated HCl per litre was added before storage.
50 mL of stock solution a) and 5 mL of the stock solutions b) to d) were combined and filled up to a final volume of 5000 mL with pure water.
The pH was adjusted to pH 7.5 with 1 M HCl solution.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Key result

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

28 d

Remarks on result:

not readily biodegradable based on QSAR/QSPR prediction

Details on results:

Percentage Biodegradation:
Nitrogen is part of the molecular structure of the test item; therefore nitrification (ThODNO3) was considered for the evaluation of the results. The criterion for ready biodegradability under the conditions of a manometric respirometry test is the degradation of the test item of at least 60%, reached within a 10-day window; the 10-day window starts when the degradation of the test item reaches at least 10% degradation.
The Test Item never reached 10% biodegradation. The mean biodegradation percentage at the end of the 28-day exposure period was 0% (ThODNO3 and ThODNH4).

In the toxicity control containing both, the test item and the reference item sodium benzoate, 48% (ThODNH4) biodegradation was noted within 14 days and 54% (ThODNH4) biodegradation after 28 days of incubation (36% and 40% based on ThODNO3). According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

BOD5 / COD results

Results with reference substance:

Percentage Biodegradation: The reference item sodium benzoate was sufficiently degraded to 96% after 14 days and to 100% after 28 days of incubation.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Biodegradation:
The degradation rate of Fluoroamidine Hydrochloride never reached 10%.
Therefore, Fluoroamidine Hydrochloride is considered to be not readily biodegradable.

Biodegradation of Reference Item Sodium Benzoate
The percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.

Biodegradation in the Toxicity Control:
According to the test guidelines the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

Executive summary:

Title:     Fluoroamidine Hydrochloride: Ready Biodegradability in a Manometric Respirometry Test

               

Guidelines:       This study was designed to comply with the following methods:

               Commission Regulation 440/2008/EC, Method C.4-D of May 30, 2008: Manometric Respirometry Test (EEC Publication No. L 142/496, May 2008)

               OECD Guideline for Testing of Chemicals No. 301 F: "Ready Biodegradability: Manometric Respirometry Test", adopted July 17, 1992

               

Material and Methods:               

Test Item:          Fluoroamidine Hydrochloride

Test Species:    Aerobic activated sludge (microorganisms from a domestic waste¬water treatment plant) was supplied by the sewage treatment plant of Rossdorf, Germany.

 

Test Design:     

The test item Fluoroamidine Hydrochloride was investigated for its ready biodegradability in a manometric respirometry test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

 

Endpoints:         

Degradation rate of test item calculated by the oxygen consumption of the aerobic activated sludge microorganisms after 28 days of incubation.

Test Item Loading Rate (initial concentration in medium C0):    102.5 mg/L corresponding to an oxygen demand of about 126.6 mg/L (ThODNH4) and 227.9 mg/L (ThODN03)

Reference Item:             Sodium Benzoate

Reference Item Loading Rate: 102.0 mg/L corresponding to an oxygen demand of about 170.0 mg/L (ThODNH4)

Test Conditions:             22°C ± 1°C, darkness

               

Results:

Biodegradation of Fluoroamidine Hydrochloride:           

Nitrogen is part of the molecular structure of the test item; therefore the evaluation of biodegradation has to be based on ThODNH4 and ThODNO3. The criterion for ready biodegradability under the conditions of a manometric respirometry test is the degradation of the test item of at least 60%, reached within a 10-day window; the 10-day window starts when the degradation of the test item reaches at least 10% degradation.

Fluoroamidine Hydrochloride never reached 10% biodegradation. The mean biodegradation at test end after 28 days was 0% (ThODNH4 and ThODNO3).

Therefore, Fluoroamidine Hydrochloride is considered to be not readily biodegradable based on ThODNH4 and ThODNO3.

Biodegradation of Sodium Benzoate:   

The reference item sodium benzoate was sufficiently degraded to 96% after 14 days and to 100% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

 

Biodegradation of the Toxicity Control:               

In the toxicity control containing both, the test item and the reference item sodium benzoate, 48% (ThODNH4) biodegradation was noted within 14 days and 54% (ThODNH4) biodegradation after 28 days of incubation (36% and 40% based on ThODNO3). According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.