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Environmental fate & pathways

Phototransformation in air

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Reference
Endpoint:
phototransformation in air
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 and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
see attached justification

1. SOFTWARE
EPI Suite 4.10
2. MODEL (incl. version number)
AOPWIN (Atmospheric Oxidation Rate Program©) Program, Version 1.92

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
see confidential details on test material

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
see attached justification

5. APPLICABILITY DOMAIN
see attached justification

6. ADEQUACY OF THE RESULT
see attached justification
Qualifier:
according to guideline
Guideline:
other: QSAR method used according to REACh guidance document on QSAR R.6
Qualifier:
according to guideline
Guideline:
other: ECHA guidance on Information Requirements and Chemical Safety Assessment, Chapter R.7b, 2017
Version / remarks:
Appendix R.7.9-4, p 274ff
Qualifier:
according to guideline
Guideline:
other: ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chaper R.11, 2017
Version / remarks:
p 61
Principles of method if other than guideline:
- Software tool(s) used including version: EPI Suite 4.10,
- Model(s) used: AOPWIN (Atmospheric Oxidation Rate Program©) Program, Version 1.92
- Model description: see 'Attached justification' QMRF_AOPWIN_Tetrabutan_representatives.pdf
- Justification of QSAR prediction: see 'Attached justification' QMRF_AOPWIN_Tetrabutan_representatives.pdf
GLP compliance:
no
Estimation method (if used):
PHOTOCHEMICAL REACTION WITH OH RADICALS
- Concentration of OH radicals:
1.5 × 10 6 molecules (radicals)/cm3 per 12-h of daylight

- Degradation rate constant:
see results table

- Temperature for which rate constant was calculated:
298 K

- Computer programme:
AOPWIN (Atmospheric Oxidation Rate Program©) Program, Version 1.92
Key result
DT50:
6.6 h
Test condition:
substance1
Key result
DT50:
6.1 h
Test condition:
substance2
Key result
DT50:
10.9 h
Test condition:
substance3
Key result
DT50:
6 h
Test condition:
substance4

see attachment: AOP 4 Tetrabutanes (C16).pdf

Validity criteria fulfilled:
not applicable
Conclusions:
For all C16 Tetrabutane isomers, the calculated half-life in the atmosphere is less than 11 hours for the reaction with naturally occuring OH radicals.
Executive summary:

For 4 representative Tetrabutane (C16) structures with different degree of branching, the atmospheric half-life for the reaction with OH-radicals was calculated with AOPWIN (Atmospheric Oxidation Rate Program) Program, Version 1.9 (default settings). The atmospheric half-life is in the range of 6.6 to 10.9 hours.

The degree of branching ranges from not branched to extremely branched. Therefore the statement that the half-life is less than 11 hours can be applied to all C16 tetrabutane isomers for the reaction with naturally occuring OH radicals.

Description of key information

For 4 representative Tetrabutane (C16) structures with different degree of branching, the atmospheric half-life for the reaction with OH-radicals was calculated with AOPWIN (Atmospheric Oxidation Rate Program) Program, Version 1.9 (default settings). The atmospheric half-life is in the range of 6.6 to 10.9 hours.

The degree of branching ranges from not branched to extremely branched. Therefore the statement that the half-life is less than 11 hours can be applied to all C16 tetrabutane isomers for the reaction with naturally occuring OH radicals.

Key value for chemical safety assessment

Half-life in air:
11 h

Additional information