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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 1
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
Test material information:
Composition 1
Specific details on test material used for the study:
- Name of test material: 1-[(2-methoxyphenyl)azo]-2-naphthol
- Molecular formula: C17 H14 N2 O2
- Molecular weight: 278.31 g/mol
- Smiles notation: c12c(\N=N\c3c(cccc3)OC)c(ccc1cccc2)O
- InChl : 1S/C17H14N2O2/c1-21-16-9-5-4-8-14(16)18-19-17-13-7-3-2-6-12(13)10-11-15(17)20/h2-11,20H,1H3/b19-18+
- 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:
29.8
Sampling time:
28 d
Remarks on result:
other: Other details not known
Details on results:
Test substance undergoes 29.8% 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 5 nearest neighbours
Domain  logical expression:Result: In Domain

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

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Aryl OR Azo OR Ether OR Fused carbocyclic aromatic OR Naphtalene OR Phenol by Organic Functional groups ONLY

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Aryl OR Azo OR Ether OR Fused carbocyclic aromatic OR Naphtalene OR Overlapping groups OR Phenol by Organic Functional groups (nested) ONLY

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Alcohol, olefinic attach [-OH] OR Aliphatic Carbon [CH] OR Aliphatic Carbon [-CH2-] OR Aliphatic Carbon [-CH3] OR Aliphatic Nitrogen, one aromatic attach [-N] OR Aromatic Carbon [C] OR Azo [-N=N-] OR Hydroxy, aromatic attach [-OH] OR Olefinic carbon [=CH- or =C<] OR Oxygen, one aromatic attach [-O-] by Organic functional groups (US EPA) ONLY

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Alkylarylether OR Aromatic compound OR Azo compound OR Ether OR Hydroxy compound OR Phenol by Organic functional groups, Norbert Haider (checkmol) ONLY

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Not calculated by Biodeg BioHC half-life (Biowin) ONLY

Domain logical expression index: "f"

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

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as Biodegrades Fast by Biodeg probability (Biowin 1) ONLY

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Does NOT Biodegrade Fast by Biodeg probability (Biowin 2) ONLY

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Does NOT Biodegrade Fast by Biodeg probability (Biowin 7) ONLY

Domain logical expression index: "j"

Parametric boundary:The target chemical should have a value of Molecular weight which is >= 158 Da

Domain logical expression index: "k"

Parametric boundary:The target chemical should have a value of Molecular weight which is <= 284 Da

Validity criteria fulfilled:
not specified
Interpretation of results:
not readily biodegradable
Conclusions:
The test chemical Octyl acetate was estimated to be readily biodegradable in water.
Executive summary:

Biodegradability of 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol (CAS no. 1229 -55 -6) is predicted using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor. Test substance undergoes 29.8% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical

1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol was estimated to be not readily biodegradable in water.

Description of key information

Biodegradability of 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol (CAS no. 1229 -55 -6) is predicted using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor (2017). Test substance undergoes 29.8% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical

1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol 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 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol(CAS No. 1229 -55 -6) and supporting weight of evidence study for its closest read across substance 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-[(2-methoxyphenyl)diazenyl]-2-naphthol(CAS No. 1229-55-6) was estimated.Test substance undergoes 29.8% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol was estimated to be not readily biodegradable in water.

 

In another prediction done using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol(CAS No. 1229 -55 -6) 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 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol is expected to be not readily biodegradable.

 

In a supporting weight of evidence study for the read across chemical 1-(phenyldiazenyl)-2-naphthol (CAS no. 842-07-9), the carbon dioxide evolution test (former Sturm test) is a static method used for evaluating the ultimate aerobic biodegradability of a read across substance 1-(phenyldiazenyl)-2-naphthol in water (Sustainability Support Services (Europe) AB has letter of access, 2003). Activated sludge was obtained from laboratory wastewater plant treating municipal sewage. Activated sludge of a concentration of 30 mg/I dry substance was pre-aerated for about two days before the start of the test. Mixtures of the test substance, a defined inorganic medium and a non pre-adapted inoculurn (e .g. activated sludge or effluent of a municipal or laboratory waste water treatment plant) are incubated and aerated at room temperature up to 28 days. The biologically produced carbon dioxide is trapped in a 0,25 mol. potassium hydroxide solution. The production of carbon dioxide (C02) is a clear indication of biodegradation. The measured amount of carbon dioxide at the end of the test is compared with the calculated maximal theoretical production (ThC02) and indicated as biodegradation degree in percent. The conductivity shift of the absorption solution is used for calculating of the C02 production. Biodegradation degree of the reference substance after 14 days (% CO2/ThCO2): 60 - 70%. The percentage degradation of the read across substance was determined to be <10% in 28 days by CO2/ThCO2 parameter. Thus, the substance 1 -(phenyldiazenyl)-2 -naphthol is considered to be not readily biodegradable according to OECD criteria.

 

On the basis of above results for target chemical1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol (from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (from experimental report), it can be concluded that the test substance 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol can be expected to be not readily biodegradable in nature.