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Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: screening tests
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification
Justification for type of information:
The supporting QMRF report has been attached
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Principles of method if other than guideline:
The data is predicted using the OECD QSAR toolbox version 3.3 with logKow as the primary descriptor.
GLP compliance:
not specified
Specific details on test material used for the study:
- Name of test material: 1-(3-aminophenyl)urea
- Molecular formula: C7 H9 N3 O
- Molecular weight: 151.168 g/mol
- Smiles notation: O=C(Nc1cccc(N)c1)N
- InChl: 1S/C7H9N3O/c8-5-2-1-3-6(4-5)10-7(9)11/h1-4H,8H2,(H3,9,10,11)
- Substance type: Organic
- Physical state: Solid
Oxygen conditions:
aerobic
Inoculum or test system:
other: Microorganisms
Duration of test (contact time):
28 d
Based on:
not specified
Parameter followed for biodegradation estimation:
other: BOD
Key result
Parameter:
other: BOD
Value:
1
Sampling time:
28 d
Remarks on result:
other: Other details not known
Details on results:
Test substance undergoes 1% degradation by BOD in 28 days.

The prediction was based on dataset comprised from the following descriptors: BOD
Estimation method: Takes average value from the 8 nearest neighbours
Domain  logical expression:Result: In Domain

((((("a" or "b" or "c" )  and "d" )  and "e" )  and "f" )  and ("g" and "h" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Anilines (Acute toxicity) by US-EPA New Chemical Categories

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Radical AND Radical >> Radical mechanism via ROS formation (indirect) AND Radical >> Radical mechanism via ROS formation (indirect) >> Single-Ring Substituted Primary Aromatic Amines AND SN1 AND SN1 >> Nucleophilic attack after metabolic nitrenium ion formation AND SN1 >> Nucleophilic attack after metabolic nitrenium ion formation >> Single-Ring Substituted Primary Aromatic Amines by DNA binding by OASIS v.1.3

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as SN1 OR SN1 >> Nitrenium Ion formation OR SN1 >> Nitrenium Ion formation >> Aromatic phenylureas OR SN1 >> Nitrenium Ion formation >> Primary aromatic amine by DNA binding by OECD ONLY

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as days - weeks by Biodeg primary (Biowin 4) ONLY

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Does NOT Biodegrade Fast by Biodeg probability (Biowin 1) ONLY

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Radical AND Radical >> Radical mechanism via ROS formation (indirect) AND Radical >> Radical mechanism via ROS formation (indirect) >> Single-Ring Substituted Primary Aromatic Amines AND SN1 AND SN1 >> Nucleophilic attack after metabolic nitrenium ion formation AND SN1 >> Nucleophilic attack after metabolic nitrenium ion formation >> Single-Ring Substituted Primary Aromatic Amines by DNA binding by OASIS v.1.3 ONLY

Domain logical expression index: "g"

Parametric boundary:The target chemical should have a value of Molecular weight which is >= 108 Da

Domain logical expression index: "h"

Parametric boundary:The target chemical should have a value of Molecular weight which is <= 244 Da

Validity criteria fulfilled:
not specified
Interpretation of results:
not readily biodegradable
Conclusions:
The test chemical 1-(3-aminophenyl)urea was estimated to be not readily biodegradable in water.
Executive summary:

Biodegradability of 1-(3-aminophenyl)urea (CAS no. 25711 -72 -2) is predicted using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor. Test substance undergoes 1% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 1-(3-aminophenyl)urea

was estimated to be not readily biodegradable in water.

Description of key information

Biodegradability of 1-(3-aminophenyl)urea (CAS no. 25711 -72 -2) is predicted using OECD QSAR toolbox version 3.3 (2017) with logKow as the primary descriptor. Test substance undergoes 1% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 1-(3-aminophenyl)urea

was estimated to be not readily biodegradable in water.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Various predicted data for the target compound 1-(3-aminophenyl)urea(CAS No. 25711-72-2) and various supporting weight of evidence studies for its closest read across substance with logKow as the primary descriptor were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction done by SSS (2017) using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor, percentage biodegradability of test chemical1-(3-aminophenyl)urea(CAS No. 25711-72-2) was estimated.Test substance undergoes 1% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 1-(3-aminophenyl)urea was estimated to be not readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound1-(3-aminophenyl)urea(CAS No. 25711-72-2) in the presence of mixed populations of environmental microorganisms was estimated.The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical  1-(3-aminophenyl)urea is expected to be not readily biodegradable.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, 2017) for the read across chemical 4-methylbenzene-1,3-diamine (CAS no. 95-80-7),biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of read across substance 4 -methylbenzene-1,3 -diamine. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of read across substance was determined to be 0, 3 and 7.9% by BOD, TOC removal and GC parameter in 14 days. Thus, based on percentage degradation, 4 -methylbenzene-1,3 -diamine is considered to be not readily biodegradable in nature.

 

For the same read across chemical 4-methylbenzene-1,3-diamine (CAS no. 95-80-7) from SRC PhysProp Database (2017), biodegradation study was conducted for 14 days for evaluating the percentage biodegradability of read across substance 4 -methylbenzene-1,3 -diamine. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)) under aerobic conditions at a temperature of 25°C and a pH of 7.0, respectively. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of read across substance was determined to be in the range of 0 -29% by BOD parameter in 14 days. Thus, based on percentage degradation, 4 -methylbenzene-1,3 -diamine is considered to be not readily biodegradable in nature.

 

In a supporting weight of evidence study for the read across chemical 2-amino-5-methylbenzene sulfonic acid (CAS no. 88-44-8),biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of read across substance 2 -amino-5 -methylbenzene sulfonic acid (J-CHECK, 2017 and OECD SIDS, 2003). The study was performed according to OECD Guide-line 301 C "Ready Biodegradability: Modified MITI Test (I)" under aerobic conditions. Aniline was used as a reference substance for the study. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. Reference substance undergoes >40% and >60% degradation in 7 and 14 days, respectively. The percentage degradation of read across substance was determined to be 0 and <0% degradation by BOD, O2 consumption, TOC removal, Test mat. analysis and UV-Vis parameter in 14 days. Thus, based on percentage degradation, 2 -amino-5 -methylbenzene sulfonic acid is considered to be not readily biodegradable in nature.

 

Another biodegradation study was conducted for evaluating the percentage biodegradability of read across substance 1,3-diaminobenzene (CAS no. 108-45-2) (George W. Malaney, 1960 and SRC PhysProp Database, 2017). Aniline-acclimated sludge was used as a test inoculum. The original source of microorganisms was mixed liquor from the aeration tank of a municipal treatment plant. Biodegradation of test chemical was tested by the conventional Warburg technique, using 125 ml flasks. Concentration of inoculum i.e, sludge used was 2,500 mg/l and initial test substance conc. used in the study was 500 mg/l. Incubation of the test vessel was carried out at 20ᵒC for 5-8 days i.e, 120-192 hrs. Oxidation in the test flask was recorded as mg O2 uptake per liter of the mixture in the flask. The mg of O2 uptake by the read across substance1,3-diaminobenzene was determined to be 210 mg/l and the percentage degradation of read across substance was determined to be 0% by BOD parameter in 8 days. Thus, based on percentage degradation,1,3 -diaminobenzene is considered to be not readily biodegradable in nature.

 

On the basis of above results for target chemical1-(3-aminophenyl)urea(from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (from authoritative database J-CHECK, SRC PhysProp Database, secondary source OECD SIDS and peer reviewed journal), it can be concluded that the test substance1-(3-aminophenyl)urea can be expected to be not readily biodegradable in nature.