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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
Study period:
12 June 2020
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
Estimation Programs Interface (EPI) Suite for Microsoft Windows, v4.11 (US EPA, 2012)

2. MODEL (incl. version number)
AOPWIN v1.92a

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
CC(C)c1cc(C(C)C)c(N=C=O)c(C(C)C)c1N=C=O

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF.

5. APPLICABILITY DOMAIN
See attached QPRF.

6. ADEQUACY OF THE RESULT
- The model is scientifically valid (see attached QMRF).
- See attached QPRF for reliability assessment.
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version: EpiSuite v4.11
- Model(s) used: AOPWIN v1.92a
- Model description: see field ''Attached justification'
- Justification of QSAR prediction: see field 'Attached justification'
Specific details on test material used for the study:
CC(C)c1cc(C(C)C)c(N=C=O)c(C(C)C)c1N=C=O
Estimation method (if used):
PHOTOCHEMICAL REACTION WITH OH RADICALS
- Concentration of OH radicals: 1.5 E6 OH/cm³
- Temperature for which rate constant was calculated: 25 °C
- Computer program: AOPWIN v1.92 by US-EPA (EPIWIN software)
Light source:
not specified
Details on light source:
Not applicable.
Details on test conditions:
The computer program estimates the gas-phase reaction rate for the reaction between the most prevalent atmospheric oxidant (hydroxyl radicals) and the desired chemical. For olefins and acetylenes the gas-phase ozone radical reaction rates are estimated as well. Additional information is given by the program if nitrate radical reaction will be important. The assumed average hydroxyl radical and ozone concentration are automatically used to calculate the atmospheric half-live for the chemical of interest.
Reference substance:
no
Remarks:
Not applicable.
Preliminary study:
Not applicable.
Test performance:
No remarks necessary.
DT50:
3.364 h
Reaction with:
OH radicals
Rate constant:
0 cm³ molecule-1 s-1
Transformation products:
not measured
Results with reference substance:
Not applicable.
Validity criteria fulfilled:
yes
Remarks:
scientifically accepted calculation method
Conclusions:
The study report describes a scientifically accepted calculation method for the phototransformation in air using the US-EPA software AOPWIN v1.92. For the test substance an overall gas-phase reaction constant (also called OH rate constant) of 38.1565 E-12 cm³/molecules-sec (= 0.000033 cm³/molecules-day) and an atmospheric half-life of 0.280 days (around 3.364 hours) was calculated. Neither an ozone reaction nor any nitrate radical reaction is important for the desired chemical.
Executive summary:

The phototransformation in air of the substance 2,4,6 -triisopropyl-m-phenylene diisocyanate was determined by the computer program AOPWIN v1.92 (EPIWIN software) by US-EPA (2012). The program estimates the gas-phase reaction rate for the reaction between the most prevalent atmospheric oxidant (hydroxyl radicals) and the desired chemical. For the test substance an overall gas-phase reaction constant (also called OH rate constant) of 38.1565 E-12 cm³/molecules-sec (= 0.000033 cm³/molecules-day) and an atmospheric half-life of 0.280 days (around 3.364 hours) was calculated. Neither an ozone reaction nor any nitrate radical reaction is important for the desired chemical.

Description of key information

Key_Phototransformation in air_QSAR: AOPWIN v1.92 (EPISuite v4.11, US EPA 2012), overall gas-phase reaction constant: 38.1565 E-12 cm³/molecules-sec (= 0.000033 cm³/molecules-day)

Key value for chemical safety assessment

Half-life in air:
0.28 d
Degradation rate constant with OH radicals:
0 cm³ molecule-1 d-1

Additional information

The phototransformation of the test material in air was determined by the computer program AOPWIN v1.92 (EPIWIN software) by US-EPA (2012). The program estimates the gas-phase reaction rate for the reaction between the most prevalent atmospheric oxidant (hydroxyl radicals) and the selected chemical. For the test substance an overall gas-phase reaction constant (also called OH rate constant) of 38.1565 E-12 cm³/molecules-sec (= 0.000033 cm³/molecules-day) and an atmospheric half-life of 0.280 days (around 3.40 hours) was calculated. Neither an ozone reaction nor any nitrate radical reaction is important for the desired chemical.

No GLP criteria are applicable for the usage of this tool, but due to the fact that it is a scientifically accepted calculation method the estimations performed are reliable with restrictions and can be used for the chemical safety assessment.