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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 atttached.
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 v3.3

GLP compliance:
not specified
Specific details on test material used for the study:
- Name of the test material: α-bromo-m-toluonitrile
- IUPAC name: 3-(bromomethyl)benzonitrile
- Molecular formula: C8H6BrN
- Molecular weight: 196.046 g/mol
- Smiles: N#Cc1cc(CBr)ccc1
- Inchi: 1S/C8H6BrN/c9-5-7-2-1-3-8(4-7)6-10/h1-4H,5H2
- Substance type: Organic
- Physical state : Solid crystalline powder (Off white)
Oxygen conditions:
aerobic
Inoculum or test system:
other: Microorganisms
Duration of test (contact time):
28 d
Parameter followed for biodegradation estimation:
other: BOD
Key result
Parameter:
other: BOD
Value:
9.113
Sampling time:
28 d
Remarks on result:
other: other details not available
Details on results:
Percent biodegrdation of test chemical 3-(bromomethyl)benzonitrile was estimated to be 9.1125 % by considering BOD as parameter 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" or "d" or "e" )  and "f" )  and "g" )  and ("h" and ( not "i") )  )  and "j" )  and "k" )  and "l" )  and ("m" and ( not "n") )  )  and ("o" and "p" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Benzyl Halides by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as SN2 OR SN2 >> SN2 reaction at sp3 carbon atom OR SN2 >> SN2 reaction at sp3 carbon atom >> Alkyl halides OR SN2 >> SN2 reaction at sp3 carbon atom >> alpha-Halobenzyls (and related cyano, sulfate and sulphonate subs. chem.) by Protein binding by OECD ONLY

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as SN2 OR SN2 >> Nucleophilic substitution at sp3 carbon atom OR SN2 >> Nucleophilic substitution at sp3 carbon atom >> Alkyl halides  OR SN2 >> Nucleophilic substitution on benzilyc carbon atom OR SN2 >> Nucleophilic substitution on benzilyc carbon atom >> alpha-Activated benzyls  by Protein binding by OASIS v1.3 ONLY

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as SN2 OR SN2 >> SN2 at an sp3 Carbon atom OR SN2 >> SN2 at an sp3 Carbon atom >> Aliphatic halides by DNA binding by OECD ONLY

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as AN2 OR AN2 >> Shiff base formation for aldehydes OR AN2 >> Shiff base formation for aldehydes >> Haloalkane Derivatives with Labile Halogen OR SN2 OR SN2 >> Acylation involving a leaving group  OR SN2 >> Acylation involving a leaving group  >> Haloalkane Derivatives with Labile Halogen OR SN2 >> Alkylation, nucleophilic substitution at sp3-carbon atom OR SN2 >> Alkylation, nucleophilic substitution at sp3-carbon atom >> Haloalkane Derivatives with Labile Halogen by DNA binding by OASIS v.1.3 ONLY

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Does NOT Biodegrade Fast by Biodeg probability (Biowin 6) ONLY

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as Does NOT Biodegrade Fast by Biodeg probability (Biowin 5) ONLY

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Non binder, without OH or NH2 group by Estrogen Receptor Binding

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Non binder, MW>500 by Estrogen Receptor Binding

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Reactive unspecified by Acute aquatic toxicity MOA by OASIS ONLY

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as Class 3 (unspecific reactivity) by Acute aquatic toxicity classification by Verhaar (Modified) ONLY

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as Bioavailable by Lipinski Rule Oasis ONLY

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Not classified by Oncologic Primary Classification

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as Alpha, beta-Haloether Reactive Functional Groups by Oncologic Primary Classification

Domain logical expression index: "o"

Parametric boundary:The target chemical should have a value of Molecular weight which is >= 126 Da

Domain logical expression index: "p"

Parametric boundary:The target chemical should have a value of Molecular weight which is <= 237 Da

Validity criteria fulfilled:
not specified
Interpretation of results:
not readily biodegradable
Conclusions:
Percent biodegrdation of test chemical 3-(bromomethyl)benzonitrile was estimated to be 9.1125 % by considering BOD as parameter and microorganisms as inoculum in 28 days.
Executive summary:

Biodegradability of test chemical 3-(bromomethyl)benzonitrile was estimated by using OECD QSAR tool box v3.3 and eight closest read across chemicals with log Kow as primary descriptor. Percent biodegrdation of test chemical 3-(bromomethyl)benzonitrile was estimated to be 9.1125 % by considering BOD as parameter and microorganisms as inoculum in 28 days. Based on the percent biodegradability it is concluded that this test chemical is not readily biodegradable.

Description of key information

Biodegradability of test chemical 3-(bromomethyl)benzonitrile was estimated by using OECD QSAR tool box v3.3 and eight closest read across chemicals with log Kow as primary descriptor. Percent biodegrdation of test chemical 3-(bromomethyl)benzonitrile was estimated to be 9.1125 % by considering BOD as parameter and microorganisms as inoculum in 28 days. Based on the percent biodegradability it is concluded that this test chemical is not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Two different predicted data studies for target chemical3-(bromomethyl)benzonitrile and experimental studies for its closest read across chemical with log Kow as primary descriptor have been studied for biodegradation in water endpoint and their results are summarized below.

In first weight of evidence study the Biodegradability of test chemical 3-(bromomethyl)benzonitrile was estimated by using OECD QSAR tool box v3.3 and eight closest read across chemicals with log Kow as primary descriptor. Percent biodegradation of test chemical 3-(bromomethyl)benzonitrile was estimated to be 9.1125 % by considering BOD as parameter and microorganisms as inoculum in 28 days. Based on the percent biodegradability it is concluded that this test chemical is not readily biodegradable.

In another weight of evidence study the Estimation Programs Interface Suite (EPI suite, 2017) was run to predict the biodegradation potential of the test compound 3-(bromomethyl)benzonitrile (CAS no. 28188 -41 -2) 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 as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical 3-(bromomethyl)benzonitrile is expected to be not readily biodegradable.

 

The supporting weight of evidence study was done from authoritative database (J Check, 2017) for read across chemical 1-(chloromethyl)-4-nitrobenzene (CAS no. 100-14-1) in this study the read across chemical 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. After 4 weeks (28 days)read across chemical1-(chloromethyl)-4-nitrobenzene showed 0.0% biodegradation by HPLC parameter and 51 % biodegradation by HPLC parameter using activated sludge as inoculum in 28 days. Based on percent biodegradability by BOD parameter it is concluded that this test chemical is not biodegradable.

 

Similarly another supporting experimental weight of study was done from same source as mentioned in above study (J check, 2017) for another read across chemical 1,2-dichloro-4-(chloromethyl)benzene (CAS no. 102-47-6) In this study the read across chemical was subjected to biodegradation test by taking sludge as inoculums at 30 mg/L concentration. Biodegradation was analysed by using BOD, TOC and GC parameters. The initial concentration of read across chemical was 100 mg/L. After 4 weeks (28 days) the read across chemical 1,2-dichloro-4-(chloromethyl)benzene showed 0.0% biodegradation by BOD and TOC parameter and 90 % biodegradation by GC parameter in 28 days. On the basis of percent biodegradation by BOD and TOC parameter it is concluded that test chemical 1,2-dichloro-4-(chloromethyl)benzene is not readily biodegradable.

On the basis of all the studies mentioned above biodegradation value by BOD parameter obtained was less than 10 % therefore it is concluded that target chemical 3-(bromomethyl)benzonitrile (CAS no. 28188 -41 -2) is expected to be not readily biodegradable in 28 days.