Registration Dossier

Administrative data

Endpoint:
phototransformation in air
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 14 June 1993 to 27 May 1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994
Report Date:
1994

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: The estimation methods used are based upon the structure-activity relationships developed by Dr. Roger Atkinson and co-workers.
Deviations:
not specified
Principles of method if other than guideline:
The Atkinson method is available in the form of a computer program The Atmospheric Oxidation Program available from:
Syracuse Research Corporation
Merrill Lane
Syracuse
New York 13210
USA
The only data required for the program to estimate a rate constant is the chemical structure of the compound. The chemical structure is entered into the program using SMILES (Simplified Molecular Input Line Entry System) notation.
The Atmospheric Oxidation Program 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 the organic compound based upon average atmospheric concentrations of hydroxyl radicals and ozone.
The Atmospheric Oxidation Program is supplied with a table containing experimental and calculated hydroxyl radical rate constants for 479 chemicals. Each time the program is used to estimate a rate constant for a new substance, a reference chemical will be selected from this table and used to show the program is functioning correctly. The reference will be selected to be as close in structure as possible to the substance under test. In cases where the test substance is a complex multi-functional molecule the use of several reference substances may be required to cover all functionalities.

GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Batch n. C103330. CH20512
Purity: 99.9%
Expiry May 1996
Appaerance: white powder
Storage conditions: room temperature

Results and discussion

Any other information on results incl. tables

Atrazine has a hydroxyl radical rate constant of 147 x 10^-12 cm3/molecule-sec. Assuming a hydroxyl radical concentration of 1.5 x 10^-6 cm3 and a 12-hour day, a half-life of 0.871 hours (52 minutes) was obtained.

The rate constants obtained for the reference compound matched exactly with the published estimates, showing that the program was running correctly

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Conclusions:
Atrazine has been estimated to have a hydroxyl radical rate constant of 147 x 10^-12 cm3/molecule-sec and a half-life of 52 minutes.