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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE: VEGA

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

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL: c1c(cccc1F)F

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
The model is based on the OECD 301C Modified MITI (I) Test data and provides a qualitative evaluation (binary classification) of ready biodegradability properties.
The QMRF is attached below.

5. APPLICABILITY DOMAIN
The applicability domain is available in the attached document below named "VegaNIC_doc_ModelGuide.pdf".
Additionnal information on whether the query chemical falls in the applicability domain of the model is provided in the section "details of results".

6. ADEQUACY OF THE RESULT
Ready biodegradability is a relevant information to determine the environmental classification according to the UN GHS and CLP.

Data source

Reference
Title:
Report - Prediction and Applicability Domain analysis for models: Ready Biodegradability model (IRFMN) 1.0.9
Year:
2017
Bibliographic source:
VEGA in silico platform version 1.1.4

Materials and methods

Test guideline
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
The model is based on the OECD 301C Modified MITI (I) Test data and provides a qualitative evaluation (binary classification) of ready biodegradability properties. It has been developed using Sarpy software, by Istituto di Ricerche Farmacologiche Mario Negri and Politecnico di Milano.
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
1,3-difluorobenzene
EC Number:
206-746-5
EC Name:
1,3-difluorobenzene
Cas Number:
372-18-9
Molecular formula:
C6H4F2
IUPAC Name:
1,3-difluorobenzene
Test material form:
liquid
Details on test material:
Name of the test material: 1,3-difluorobenzene
No data available
Specific details on test material used for the study:
SMILES: c1c(cccc1F)F

Results and discussion

% Degradation
Key result
Parameter:
probability of ready biodegradability (QSAR/QSPR)
Remarks on result:
not readily biodegradable based on QSAR/QSPR prediction
Details on results:
The report of the model indicates that the result may be not reliable. Therefore, a check of the information given in the report was done, paying particular attention to the following issues (as recommanded by the model):
- only moderately similar compounds with known experimental value in the training set have been found : ortho and meta dichlorobenzenes are identified as similar compounds in the training set. The analogy with these compounds is considered as sufficiently robust for the assessment of 1,3-difluorobenzene.
- a prominent number of atom centered fragments of the compound have not been found in the compounds of the training set or are rare fragments (2 unknown fragments found) : The benzene ring and the fluorine elements are covered in the training set which enables the consideration of the entire chemical structure of 1,3-difluorobenzene.

Based on the above information, the prediction is considered as sufficiently robust for 1,3-difluorobenzene. Moreover, the conclusion as "not readily biodegradable" is a worst case scenario.

Applicant's summary and conclusion

Interpretation of results:
not readily biodegradable
Conclusions:
1,3-difluorobenzene is considered as not readily biodegradable.
Executive summary:

1,3-difluorobenzene is considered as not readily biodegradable based on QSAR prediction.

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