Registration Dossier

Administrative data

Endpoint:
phototransformation in air
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data are taken from published, peer-reviewed journal articles. The data are presented in review articles and no information is available on the data sources.

Data source

Reference
Reference Type:
review article or handbook
Title:
Gas-phase tropospheric chemistry of organic compounds: a review
Author:
Atkinson R
Year:
1990
Bibliographic source:
Atmospheric Environment. 24A (1): 1-41

Materials and methods

Principles of method if other than guideline:
Guideline not stated. Kinetic data taken from Atkinson R (1990). Kinetics and mechanisms of the gas-phase reactions of the hydroxyl radical with organic compounds. Journal of Physical and Chemical Reference Data.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
No data reported
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable

Study design

Estimation method (if used):
The half-life of 1,2,4-trimethylbenzene was calculated using the formula: half-life = ln2/(rate constant*OH concentration*time) where the OH concentration is 5E+05 and the time is 86400 seconds.
Light source:
not specified
Details on light source:
No data reported
Details on test conditions:
Kinetic data taken from Atkinson R (1990). Kinetics and mechanisms of the gas-phase reactions of the hydroxyl radical with organic compounds. Journal of Physical and Chemical Reference Data.
Reference substance:
not specified

Results and discussion

Preliminary study:
The kinetic rate constant for the reaction of 1,2,4-trimethylbenzene with OH radicals is measured to be 32.5 E+12 cm3/mol/s.
Test performance:
The atmospheric half-life of 1,2,4-trimethylbenzene is calculated to be approximately 12 hours.
% Degradation
% Degr.:
50
Sampling time:
12 h
Degradation rate constant
Reaction with:
OH radicals
Rate constant:
0 m³ molecule-1 s-1
Transformation products:
not specified
Results with reference substance:
Not applicable

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Conclusions:
The kinetic rate constant for the reaction of 1,2,4-trimethylbenzene with OH radicals is measured to be 32.5-40 E+12 cm3/mol/s, indicating that the atmospheric half-life would be 12 hours.
Executive summary:

Atkinson (1990) is a review article, with no data reported on the test methods or conditions of the original data source. Never-the-less, the data are taken from a published, peer-reviewed journal article and are considered to be suitable as supporting data for this endpoint. The measured results provide a rate constant of the reaction of 1,2,4 -trimethylbenzene with OH radicals of 32.5 E+12 cm3/mol/s. The results indicate that the substance would have an atmospheric half-life of approximately 12 hours and therefore would not be persistent in the atmospheric compartment.