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Environmental fate & pathways

Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
supporting study
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
VEGA v1.1.4

2. MODEL (incl. version number)
Ready Biodegradability model (IRFMN) 1.0.9

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
O=C1Oc2ccccc2(C(=O)N1)

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
[Explain how the model fulfils the OECD principles for (Q)SAR model validation. Consider attaching the QMRF or providing a link]
See attacged QMRF

5. APPLICABILITY DOMAIN
[Explain how the substance falls within the applicability domain of the model]
- Descriptor domain:
Not applicable as the QSAR is based on structural alerts.
- Structural and mechanistic domains:
All atom entered fragments of the compound have been found in the compounds of the training dataset.
- Similarity with analogues in the training set:
Similarity Index = 0.831.
Explanation: only moderately similar compounds with known experimental value in the training set have been found. However, these do capture the estimated most important molecular structures for the ready biodegradability: the benzene ring bonded with a OC(=O)N1 fragment.
- Other considerations (as appropriate):
The concordance index for similar molecules is quite low (0.338). However, for the similar molecules where the predictions do not correspond with the experimental values, the predicted values are possible readily biodegradable instead of readily biodegradable. Because these predictions are close to experimental values and because the predicted value of the test compound is NON readily biodegradable, this was not considered an issue.

6. ADEQUACY OF THE RESULT
[Explain how the prediction fits the purpose of classification and labelling and/or risk assessment]
Following this QSAR prediction, the test substance is considered as not readily biodegradable for any risk assessment of classificaiton purposes.
Qualifier:
according to
Guideline:
other: Guidance on information requirements and chemical safety assessment Chapter R.6: QSARs and grouping of chemicals
Specific details on test material used for the study:
SMILES: O=C1Oc2ccccc2(C(=O)N1)
Remarks on result:
not readily biodegradable based on QSAR/QSPR prediction
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Using the VEGA Ready Biodegradation model (IRFMN) 1.0.9, CH02586 was predicted to be non readily biodegradable.
The substance falls within the applicability domain of the QSAR and the prediction is therefore regarded as reliable.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reason / purpose:
read-across source
Parameter:
% degradation (CO2 evolution)
Remarks:
%Defr. calculated as ratio between CO2 produced (cumulative) and ThCO2 of the test substance.
Value:
18
Sampling time:
28 d
Details on results:
Points of degradation plot (test substance):
0 % degradation after 2 d
5 % degradation after 5 d
7 % degradation after 7 d
8 % degradation after 9 d
12 % degradation after 14 d
12 % degradation after 19 d
14 % degradation after 23 d
14 % degradation after 27 d
16 % degradation after 29 d
Results with reference substance:
Points of degradation plot (reference substance):
1 % degradation after 2 d
4 % degradation after 5 d
7 % degradation after 7 d
8 % degradation after 9 d
11 % degradation after 14 d
11 % degradation after 19 d
11 % degradation after 23 d
16 % degradation after 27 d
20 % degradation after 29 d

In the toxicological control the test substance was found not to inhibit microbial activity.

Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily biodegradable
Conclusions:
Read-across from a structurally similar substance was used to assess the ready biodegradability of CH02586.
Based on this, CH02586 should be considered not readily biodegradable.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
1992
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Version / remarks:
1992
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Duration of test (contact time):
28 d
Reference substance:
other: Sodium acetate
Parameter:
% degradation (CO2 evolution)
Remarks:
%Defr. calculated as ratio between CO2 produced (cumulative) and ThCO2 of the test substance.
Value:
18
Sampling time:
28 d
Details on results:
Points of degradation plot (test substance):
0 % degradation after 2 d
5 % degradation after 5 d
7 % degradation after 7 d
8 % degradation after 9 d
12 % degradation after 14 d
12 % degradation after 19 d
14 % degradation after 23 d
14 % degradation after 27 d
16 % degradation after 29 d
Results with reference substance:
Points of degradation plot (reference substance):
1 % degradation after 2 d
4 % degradation after 5 d
7 % degradation after 7 d
8 % degradation after 9 d
11 % degradation after 14 d
11 % degradation after 19 d
11 % degradation after 23 d
16 % degradation after 27 d
20 % degradation after 29 d

In the toxicological control the test substance was found not to inhibit microbial activity.

Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily biodegradable

Description of key information

A similar chemical was tested and found to not readily biodegrade (OECD 301B). This conclusion for CH02586 was supported by a QSAR prediction with the Ready Biodegradability model IRFMN v1.0.9.

Key value for chemical safety assessment

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

Additional information