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Diss Factsheets

Environmental fate & pathways

Phototransformation in air

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Administrative data

Link to relevant study record(s)

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:
Episuite and the AOPWIN models are well documented and commonly used QSARs for predicting the potential indirect photolysis of chemicals in the atmosphere. Substances within LOA fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.
Qualifier:
no guideline required
Principles of method if other than guideline:
The Atmospheric Oxidation Program for Microsoft Windows (AOPWIN) estimates the rate constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals.  It also estimates the rate constant for the gas-phase reaction between ozone and olefinic/acetylenic compounds. The rate constants estimated by the program are then used to calculate atmospheric half-lives for organic compounds based upon average atmospheric concentrations of hydroxyl radicals and ozone. The author used data from other investigators. This data was generated using two methods: absolute and relative constant techniques. The author then applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.
GLP compliance:
no
Estimation method (if used):
The rate constants were taken from experiments using absolute techniques (flash photolysis) and relative constant techniques.
Key result
DT50:
>= 0.075 - <= 5.49 d
Test condition:
Author reports a recommended rate constant of 1.47E-11 cm3/molecule/second. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 5 E+05 molecule/cm3.
Remarks on result:
other: Result from QSAR
Key result
Reaction with:
OH radicals
Rate constant:
>= 0 - <= 0 cm³ molecule-1 s-1
Transformation products:
not specified
Results with reference substance:
Data not reported
Validity criteria fulfilled:
not applicable
Remarks:
non-standard test
Conclusions:
The estimated half life of Distillates (Petroleum), steam-cracked, dimerised (C5-12, C10-rich) is 0.075 - 5.49 d based on a recommended rate constant of 1.95E-12 - 1.43E-10 cm3/molecule/second.
Executive summary:

The indirect photolysis half-life was estimated using the EPISUITE v4.11 program and the methodology described by Atkinson et al. (1985). The estimated half life of Distillates (Petroleum), steam-cracked, dimerised (C5-12, C10-rich) is 0.075 - 5.49 d based on a recommended rate constant of 1.95E-12 - 1.43E-10 cm3/molecule/second.

Description of key information

The estimated half life of Distillates (Petroleum), steam-cracked, dimerised (C5-12, C10-rich) is 0.075 - 5.49 d based on a recommended rate constant of 1.95E-12 - 1.43E-10 cm3/molecule/second.

Key value for chemical safety assessment

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

Additional information