Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Phototransformation in air

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
phototransformation in air
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Qualifier:
according to guideline
Guideline:
other: U.S. EPA Determination of Rates of Reaction in the GAS - Phase in the Troposphere 796.3900 (1992)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline draft (Photochemical Oxidative Degradation in the Atmosphere)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: Commission Directive 94/37/EC of 22 July 1994, Official Journal of the European Communities, Annex I, Point 2.10.
Deviations:
no
GLP compliance:
no
Estimation method (if used):
PHOTOCHEMICAL REACTION WITH OH RADICALS
- The relationship between the bimolecular rate constant for –OH radical addition to the aromatic rings and the sum of the electrophillic substituent constants of the aromatic rings is (Σσ+) employed.
- Concentration of OH radicals: [OH] = 1.5 x 10e6 molecules/cm³
- Temperature for which rate constant was calculated: 25°C
- Computer program: AOP v1.92

Hydrogen Abstraction: Group rate constants (k x 10e12 cm³ molecules/sec) are 0.136 for primary carbon, 0.934 for secondary carbon, and 1.94 for tertiary carbons. Substituent factors for hydrogen abstraction are designated as F(X).
Key result
DT50:
0.208 d
Test condition:
12-hr day; 1.5E6 OH/cm3
Remarks on result:
other: For the test substance
Key result
DT50:
7.391 d
Test condition:
12-hr day; 1.5E6 OH/cm3
Remarks on result:
other: For the test substance metabolite
Key result
Reaction with:
OH radicals
Rate constant:
0 cm³ molecule-1 s-1
Remarks on result:
other: For the test substance
Key result
Reaction with:
ozone
Rate constant:
0 cm³ molecule-1 s-1
Remarks on result:
other: For the test substance
Key result
Reaction with:
OH radicals
Rate constant:
0 cm³ molecule-1 s-1
Remarks on result:
other: For the test substance metabolite
Transformation products:
no
Validity criteria fulfilled:
yes
Conclusions:
Test substance:
Overall OH rate constant: 51.4567E-12 cm³/molecule/sec
Half-life (12-hr day): 0.208 Days (1.5E6 OH/cm³) or 2.494 Hrs
Overall ozone rate constant: 10.500000E-17 cm³/molecule/sec
Half-life (Ozone reaction): 0.109 Days (at 7E11 mol/cm³) or 2.619 Hrs

Test substance metabolite:
Overall OH rate constant: 1.4471E-12 cm³/molecule/sec
Half-life (12-hr day): 7.391 Days (1.5E6 OH/cm³) or 88.696 Hrs
No ozone reaction estimation was done
Executive summary:

The calculation of the second-order rate constant and associated half-life for the reaction of the test substance and its metabolite, IN-QDY64, in the gas phase in the troposphere, using the method of Atkinson is provided. This calculation is an estimate of the photochemical oxidative degradation (indirect phototransformation) of the test substance and IN-QDY64. The overall OH rate constant for picoxystrobin is 51.46 x 10e-12 cm3/molecule-sec and the OH rate constant for IN-QDY64 is 1.45 x 10e-12 cm³/molecule-sec. The half–lives (t1/2) of the test substance and IN-QDY64 for reaction with average daily air concentrations of hydroxyl radicals (12-hr day; 1.5 x 10e6 OH radicals per cm3) are 2.49 hours and 88.7 hours respectively. Hydrogen abstraction, reaction with N and –OH and addition to aromatic rings are predicted to contribute to the rate of photochemical degradation.

Description of key information

Half-life is 0.208 days or 2.494 hours (12 -hour day)

Key value for chemical safety assessment

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

Additional information