1-Propanesulfonamide, N-[3-[[5-bromo-1-(2,6-dichlorobenzoyl)-1H-pyrrolo[2,3-b]pyridin-3-yl]carbonyl]-2,4-difluorophenyl]-

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-11-12 to 2009-12-14

Reliability:

2 (reliable with restrictions)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))

Deviations:

yes

Remarks:

The test substance is a water insoluble (<1 mg/L) solid. No details were given in the report of how a 30 mg/L concentration in the sludge was achieved (this procedure is described in Annex III of the guideline).

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

N-{3-[5-bromo-1-(2,6-dichlorobenzoyl)-1H-pyrrolo[2,3-b]pyridine-3-carbonyl]-2,4-difluorophenyl}propane-1-sulfonamide

EC Number:

806-756-5

Cas Number:

1262985-24-9

Molecular formula:

C24 H16 Br Cl2 F2 N3 O4 S

IUPAC Name:

N-{3-[5-bromo-1-(2,6-dichlorobenzoyl)-1H-pyrrolo[2,3-b]pyridine-3-carbonyl]-2,4-difluorophenyl}propane-1-sulfonamide

Test material form:

other: solid

Details on test material:

Purity >99% w/w
Water solubility: <1 mg/L

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Not adapted activated sludge from the aeration tank of the ARA Werdhölzli (CH-8048 Zürich), a municipal biological waste water treatment plant. 100 mg/l dry matter in the final mixture.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

29.5 mg/L

Based on:

ThOD/L

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

The activated sludge was used after sampling from the treatment plant without adaptation. However, the sludge was pre-conditioned for 1 day (aerated but not fed) to reduce the amount of O2 consumed by the blank controls.
Prior to the test the sludge was washed twice with tap water. The test material was directly added to the test solutions to give the final test concentration of about 30 mg/L. This refers to a ThOD value of about 45.4 mg O2/L.
The reference material was dissolved in the test medium to give a final test concentration as ThOD of about 166 mg O2/L (i.e. about 100 mg/L reference substance).
In the toxicity control about 30 mg/L test substance and about 30 mg/l reference substance were tested as a mixture.
For each test series the following number of test flasks was set up:
T: Test suspension containing inoculum, test medium and test substance (two replicates)
B: Inoculum blank containing inoculum and test medium (two replicates)
R: Procedure control containing inoculum, test medium and sodium benzoate as ready biodegradable reference compound (two replicates)
C: Abiotic sterile control: containing test substance, ultra pure water and 0.2 mM HgCl2 as sterilizing agent to prevent microbial decomposition
X: Toxicity control: containing inoculum + test medium + test substance + sodium benzoate as ready biodegradable reference compound

The test vessels were stirred by an inductive stirring system for a maximum test period of 28 days. During the test the O2 uptake was continuously measured with a manometric BOD measuring device. The pH-value was checked at the beginning and at the end of the test. The value at the beginning was adjusted to pH 7.2 (± 0.2) with NaOH or HCl, respectively.
The biodegradation of the test material was followed by daily measurements. Additionally, ultimate biodegradation was determined based on theoretical carbon content and the analyses of dissolved organic carbon (DOC) concentrations at the end of the test.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Details on results:

Based on the data of the individual O2 determinations, no biodegradability in the Modified MITI Test (II) of the test item was observed after 28 days. The respective DOC concentrations at the beginning and at the end of the test after 28 days were (in mg/l):
13.6* and 0.82 for the test units (mean of two replicates)
<0.5 and 1.04 for the inoculum blank (mean of two replicates)
58.2 and 1.51 for the procedure control (mean of two replicates)
* theoretical concentration based on molecular formula
The calculated elimination based on DOC measurement reached 100% for the Test Substance and 99% for sodium benzoate. The data show that although the test substance is not biodegradable it will be completely retained in sewage treatment plants.
Based on these results the test substance cannot be termed as inherently biodegradable in the Modified MITI Test (Il), since less than 20% degradation was attained after 28 days of incubation.

BOD5 / COD results

Results with reference substance:

The positive control, sodium benzoate, reached 79% biodegradation after 7 days and 86% biodegradation after 14 days, thus confirming suitability of inoculum and test conditions.

Any other information on results incl. tables

At the applied initial test concentration of 29.5 mg/L the test substance showed no significant toxic effect on the microbial population, since the biodegradation of the mixture (test substance + reference compound sodium benzoate) was within the expected theoretical value during the whole test period.

The test substance was not abiotically degraded (by processes using O2) during the whole test period of 28 days in the absence of microorganisms as confirmed by the lack of oxygen consumption.

At the end of the test the pH value of both inoculum blanks and the procedure control was 6.3 and 7.3, respectively. The pH values of the test suspensions were 6.2, 6.2 and 6.6.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test substance was not biodegradable in the Modified MITI Test (II) under the conditions used.

Executive summary:

Method: The biodegradability of the test substance exposed to microorganisms derived from activated sludge of a municipal sewage treatment plant was investigated under aerobic static exposure conditions in the Modified MITI Test (11). The activated sludge was used after sampling from the treatment plant without adaptation. The test material (solid) was directly added to the test solutions to give the final test concentration of about 30 mg/L. The test vessels were stirred by an inductive stirring system for a maximum test period of 28 days. During the test the O2 uptake was continuously measured with a manometric BOD measuring device.

Results: No biodegradability of the test substance based on O2 consumption was observed during 28 days as compared to the theoretical oxygen demand (ThOD). The procedure control sodium benzoate reached 86% biodegradation after 14 days, thus confirming suitability of inoculum and test conditions. At the applied initial test concentration of 30 mg/L the test substance showed no significant toxic effect on the microbial population, since the biodegradation of the mixture (test substance + reference compound sodium benzoate) was within the expected theoretical value during the whole test period. The calculated elimination based on DOC measurement reached 100% for the test substance and 99% for sodium benzoate. The data show that the test substance will be completely retained in sewage treatment plants.

Conclusion: The test substance was not biodegradable in the Modified MITI Test (II) under the conditions used.