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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
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Principles of method if other than guideline:
The prediction was done by using OECD QSAR tool box v3.4
GLP compliance:
not specified
Test material information:
Composition 1
Specific details on test material used for the study:
- Name of test material: 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile
- IUPAC name: 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile
- Molecular formula: C18H19N5O4
- Molecular weight: 369.38 g/mole
- Smiles : Cc1cc(N(CCO)CCO)ccc1N=Nc1ccc(N(=O)=O)cc1C#N
- Substance type: Organic
- Physical state: Solid powder (violet)
Inoculum or test system:
other: Microorganisms
Duration of test (contact time):
28 d
Parameter followed for biodegradation estimation:
other: BOD
Key result
Parameter:
other: % degradation by BOD
Value:
1.72
Sampling time:
28 d
Remarks on result:
other: other details not available
Details on results:
The percent degradability of test chemical 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile was estimated to be 1.72 % by considering BOD as parameter and Microorganisms as inoculum in 28 days.

The prediction was based on dataset comprised from the following descriptors: BOD
Estimation method: Takes average value from the 5 nearest neighbours
Domain  logical expression:Result: In Domain

((((((("a" or "b" )  and "c" )  and "d" )  and "e" )  and "f" )  and ("g" and ( not "h") )  )  and ("i" and "j" )  )

Domain logical expression index: "a"

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

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Radical OR Radical >> Radical mechanism via ROS formation (indirect) OR Radical >> Radical mechanism via ROS formation (indirect) >> Nitro Azoarenes OR SN1 OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Nitro Azoarenes by DNA binding by OASIS v.1.4 ONLY

Domain logical expression index: "c"

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

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as months and longer by Biodeg ultimate (Biowin 3) ONLY

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Not calculated by Hydrolysis half-life (Kb, pH 7)(Hydrowin) ONLY

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Not calculated by Hydrolysis half-life (pH 6.5-7.4) ONLY

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as Not Related to an Existing ECOSAR Class by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Acid moiety by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "i"

Parametric boundary:The target chemical should have a value of Molecular weight which is >= 318 Da

Domain logical expression index: "j"

Parametric boundary:The target chemical should have a value of Molecular weight which is <= 507 Da

Validity criteria fulfilled:
not specified
Interpretation of results:
not readily biodegradable
Conclusions:
The percent biodegradability of test chemical 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile (CAS no. 12236-25-8) was estimated to be 1.72 % by considering BOD as parameter and microorganisms as inoculum in 28 days. On the basis of percent biodegradation it can be concluded that test chemical is 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile is not readily biodegradable.
Executive summary:

Biodegradability of test chemical 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile (CAS no. 12236 -25 -8) was estimated by uisng OECD QSAR tool box v3.4 considering five closest read across chemicals with log kow as primary descriptor. The percent biodegradability of test chemical 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile (CAS no. 12236-25-8) was estimated to be 1.72 % by considering BOD as parameter and microorganisms as inoculum in 28 days. On the basis of percent biodegradation it can be concluded that test chemical is  2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile is not readily biodegradable.

Description of key information

Biodegradability of test chemical 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile (CAS no. 12236 -25 -8) was estimated by uisng OECD QSAR tool box v3.4 considering five closest read across chemicals with log kow as primary descriptor. The percent biodegradability of test chemical 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile (CAS no. 12236-25-8) was estimated to be 1.72 % by considering BOD as parameter and microorganisms as inoculum in 28 days. On the basis of percent biodegradation it can be concluded that test chemical is  2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile is not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Predicted data studies for target chemical 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile (CAS no. 12236 -25 -8)and one experimental study for its structurally similar read across chemical have been conducted and their results are summarized below biodegradation in water endpoint.

 

In first predicted data study biodegradability of test chemical 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile (CAS no. 12236 -25 -8) was estimated by using OECD QSAR tool box v3.4 considering five closest read across chemicals with log kow as primary descriptor. The percent biodegradability of test chemical 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile (CAS no. 12236-25-8) was estimated to be 1.72 % by considering BOD as parameter and microorganisms as inoculum in 28 days. On the basis of percent biodegradation it can be concluded that test chemical is 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile is not readily biodegradable.

 

 In another predicted data study the Estimation Programs Interface Suite (EPI suite, 2017) was run to predict the biodegradation potential of the test compound 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile (CAS no. 12236 -25 -8) in the presence of mixed populations of environmental microorganisms. 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 Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical  2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile is expected to be not readily biodegradable.

 

Next study was experimental study done from authoritative database (J check, 2017) for read across chemical 1-(4-methyl-2-nitrophenylazo)-2-naphthol (CAS no. 2425-85-6) in this study the read across chemical 1-(4-methyl-2-nitrophenylazo)-2-naphthol (CAS no. 2425-85-6) was subjected to biodegradation test by taking sludge as inoculums at 30 mg/L concentration. Biodegradation was analysed by using BOD and HPLC parameters. The initial concentration of read across chemical was 100 mg/L. The read across chemical1-(4-methyl-2-nitrophenylazo)-2-naphthol showed 0 % biodegradability by BOD parameter and 1 % by HPLC parameter and activated sludge as inoculumin 28 days. On the basis of percent degradability value it is concluded that read across chemical 1-(4-methyl-2-nitrophenylazo)-2-naphthol is not readily biodegradable.

 

On the basis of results of all the studies mentioned above it can be concluded that test chemical 2-[[4-[bis(2-hydroxyethyl)amino]-o-tolyl]azo]-5-nitrobenzonitrile (CAS no. 12236 -25 -8) is not readily biodegradable.