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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
November 2017
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 adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
Model: BIOWIN v4.10
Submodel: Ready Biodegradation (OECD 301C, MITI): Biowin 5 and Biowin 6

2. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
- 1CGE-1MPMD adduct CC(CN)CCCNCC(O)COc1ccccc1C
- 2CGE-1MPDA adduct isomer Cc1ccccc1OCC(O)CNCCCC(C)CNCC(O)COc1ccccc1C
- 3CGE-1MPMD Cc1ccccc1OCC(O)CNCC(C)CCCN(CC(O)COc1ccccc1C)C(O)COc1ccccc1C
- mephenesin Cc1ccccc1OCC(O)CO
- di-CGE Cc1ccccc1OCC(O)COc1ccccc1C
- MPMD CC(CN)CCCN

3. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
The model estimates the ready biodegradability of an organic compound in the presence of microorganisms in an aqueous medium under aerobic condition. The oxygen uptake of microorganisms is measured for 28 days (biological oxygen demand, BOD). The pass levels for ready biodegradability are 60 % removal of BOD. The compounds were tested following MITI test rules. The 10 days window concept does not apply to the MITI method. The Biowin Biodegradability categorisation scheme is based on the structural fragments used by the MITI Biodegradation Probability Models. Seven biodegradation models are included in Biowin. The dataset for Biowin 5 and 6 consists of 884 organic chemicals of which 385 evaluated as “readily biodegradable” and 499 evaluated as “not readily biodegradable”. Estimations are based on fragment coefficients derived from linear (Biowin 5) or non-linear (Biowin 6) regression analyses depending on the model.

4. APPLICABILITY DOMAIN
Descriptor domain:
- Molecular weight MW: 30.02 ≤ MW ≤ 959.2 [g/mol]
MWs of the components of CGE-PMDA range from 116 to 595 g/mol.

5. ADEQUACY OF THE RESULT
Estimations are based on fragment coefficients derived from linear (Biowin 5) or non-linear (Biowin 6) regression analyses depending on the model. The QSAR models for BIOWIN v4.10 are considered reliable based on the numbers (N) of analogues in the training set, and the accuracy of the prediction for compounds in the training set and validation set.



Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Principles of method if other than guideline:
Approximately 900 discrete substances were tested in the Ministry of International Trade and Industry (MITI)-I test: Estimation of the aerobic biodegradation of an organic compound in the presence of mixed populations of microorganisms. Biodegradation is expressed as the percentage oxygen uptake. The BIOWIN Biodegradability categorisation scheme is based on the structural fragments used by the MITI Biodegradation Probability Models

GLP compliance:
no
Remarks:
Not applicable for QSAR
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic, non-adapted
Duration of test (contact time):
28 d
Parameter followed for biodegradation estimation:
O2 consumption
Key result
Parameter:
% degradation (O2 consumption)
Value:
< 60
Sampling time:
28 d
Remarks on result:
not readily biodegradable based on QSAR/QSPR prediction

Model

1CGE-1MPMD adduct

2CGE-1MPMD adduct isomer

3CGE-1MPMD

mephenesin

di-CGE

MPMD

Biowin 5

(MITI Linear)

0.57

Readily Degradable

0.56

Readily Degradable

0.43

not Readily Degradable

0.81

Readily Degradable

0.65

Readily Degradable

0.58

Readily Degradable

Biowin 6

(MITI Non-Linear)

0.35

not Readily Degradable

0.18

not Readily Degradable

0.05

not Readily Degradable

0.90

Readily Degradable

0.66

Readily Degradable

0.56

Readily Degradable

 VEGA (Ready Biodegradation model, IRFMN)  not Readily Biodegradable  not Readily Biodegradable  not Readily Biodegradable  not Readily Biodegradable  not Readily Biodegradable  Possible Readily Biodegradable
Conclusions:
CGE-PMDA is considered not to be readily biodegradable.

Description of key information

The readily biodegradation potential of CGE-PMDA adduct has been assessed using the QSAR models Biowin 5 and Biowin 6, implemented in BIOWIN v4.10. The QSAR model fulfills the OECD criteria for regulatory acceptance.

The models estimate the ready biodegradability of organic compounds in the presence of microorganisms in aqueous medium under aerobic conditions. The oxygen uptake of microorganisms is measured for 28 days (biological oxygen demand, BOD). The pass levels for ready biodegradability are 60 % removal of BOD. Approximately 900 strict compounds were tested following Japanese Ministry of International Trade and Industry (MITI) test rules. The Biowin Biodegradability categorization scheme is based on the structural fragments used by the MITI Biodegradation Probability Models. The dataset for Biowin 5 and Biowin 6 consists of 884 organic chemicals of which 385 evaluated as “readily biodegradable” and 499 evaluated as “not readily biodegradable”. Estimations are based on fragment coefficients derived from linear (Biowin 5) or non-linear (Biowin 6) regression analyses depending on the model.

CGE-PMDA is a mixture of multi constituents. All constituents are within the descriptor domain (30.02 ≤ MW ≤959.2 [g/mol]).

CGE-PMDA is considered as not readily degradable, although the results of Biowin 5 and Biowin 6 are non-conclusive for the two constituents 1CGE-1MPMD adduct and 2CGE-1MPMD adduct isomer. To validate the result, readily biodegradation was also assessed using the in silico platform VEGA. The results are consistent with Biowin 6 results for 1CGE-1MPMD adduct and 2CGE-1MPDA adduct isomer.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information