Pyrasulfotole

Phototransformation in air

Link to relevant study record(s)

Reference

Endpoint:

phototransformation in air

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

11 Jan 2005

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

Qualifier:

according to guideline

Guideline:

other: Commission Directive, 95/36/EC, amending Council Directive 91/414/EEC concerning the placing of plant protection products on the market: Annex II, Fate and Behavior in the Environment, 7171/VI/94-EN, 7.2.2.3 Photolysis in Air

Qualifier:

according to guideline

Guideline:

other: Federal Biological Institute for Agriculture and Forestry (BBA), Germany: Guidelines for the Testing of Plant Protection Products in Registration Procedure, Part IV, 6-1 “Determination of the volatilization and the fate of plant protectants in the air.”

Version / remarks:

1990

Qualifier:

according to guideline

Guideline:

other: Canada PMRA DACO Number 8.2.3.3.3

Principles of method if other than guideline:

Calculation of the Indirect Photolysis Reaction Using the Incremental Method of Atkinson and the Program AOPWIN, version 1.91

GLP compliance:

no

Remarks:

Not applicable for this modeling report.

Estimation method (if used):

Atmospheric Oxidation Program (AOPWIN), estimates the rate constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals. “Short-term” refers to a 12-hr day (because OH radicals exist only during sunlight hours) and an OH concentration of 1.5E+06 radical/cm3 (an average concentration for daylight hours only). “Long-term” refers to a 24-hr day and an OH concentration of 0.5E+06 radical/cm3 (average including dark hours when OH concentration is zero).

Key result

DT50:

10.3 h

Test condition:

Time frame: long term 24 h day

Remarks on result:

other: Half-life due to reaction with OH radicals

DT50:

3.4 h

Test condition:

Time frame: short term 12 h day

Remarks on result:

other: Half-life due to reaction with OH radicals

Transformation products:

not measured

Output from AOPWIN:

Calculation of the Indirect Photolysis Reaction Using the Incremental Method of Atkinson and the Program AOPWIN, version 1.91 according to William Meylan, Philip Howard, Syracuse Research Corporation, Environmental Science Center, Merill Lane, Syracuse, NY 13212-2510, USA 1996:

------------------- SUMMARY (AOP v1.91): HYDROXYL RADICALS -------------------

**Hydrogen Abstraction = 1.3328 E-12 cm3/molecule-sec

Reaction with N, S and -OH = 0.1400 E-12 cm3/molecule-sec

Addition to Triple Bonds = 0.0000 E-12 cm3/molecule-sec

Addition to Olefinic Bonds = 0.0000 E-12 cm3/molecule-sec

**Addition to Aromatic Rings = 36.0575 E-12 cm3/molecule-sec

Addition to Fused Rings = 0.0000 E-12 cm3/molecule-sec

OVERALL OH Rate Constant = 37.5303 E-12 cm3/molecule-sec

HALF-LIFE = 0.285 Days (12-hr day; 1.5E6 OH/cm3)

HALF-LIFE = 3.420 Hrs

HALF-LIFE = 0.427 Days (24-hr day; 0.5E6 OH/cm3)

HALF-LIFE = 10.260 Hrs

........................ ** Designates Estimation(s) Using ASSUMED Value(s)

------------------- SUMMARY (AOP v1.91): OZONE REACTION ----------------------

****** NO OZONE REACTION ESTIMATION ******

(ONLY Olefins and Acetylenes are Estimated)

NOTE: Reaction with Nitrate Radicals May Be Important!

Experimental Database: NO Structure Matches

Hydrogen Abstraction Calculation:

Kprim = 0.136 F(S(+4,+6) **)=0.136(7.800)= 1.061

Kprim = 0.136 F(-Aromatic)=0.136(1.000)= 0.136

Kprim = 0.136 F(-Aromatic)=0.136(1.000)= 0.136

H Abstraction TOTAL = 1.333 E-12 cm3/molecule-sec

...................................ASSUMED Values designated by: **

Reaction Rates With Nitrogen, Sulfur and -OH:

K(-OH) = 0.140 E-12 cm3/molecule-sec

OH Addition to Aromatic Rings Calculation:

Most negative Es+ = 0.000

Log Kar = -10.4437 - 1.34(Es+) cm3/molecule-sec

where -10.4437 is the measured parent value for imidazole

Ring #1 Kar = 36.000 E-12 cm3/molecule-sec

Es+ = sm+(-S+6 **) + sp+(-C(=O)- **) + sm+(-CF3) + = 1.300

Es+ = sp+(-S+6 **) + sm+(-C(=O)- **) + sp+(-CF3) + = 1.142

Es+ = sp+(-S+6 **) + sm+(-C(=O)- **) + sp+(-CF3) + = 1.142

Most negative Es+ = 1.142

Log Kar = -11.71 - 1.34(Es+) cm3/molecule-sec

Ring #2 Kar = 0.0575 E-12 cm3/molecule-sec

TOTAL Kar = 36.0575 E-12 cm3/molecule-sec

...................................ASSUMED Values designated by: **

Validity criteria fulfilled:

not applicable

Description of key information

DT50 (24 h-day): 10.3 h (AOPWIN v1.91)

Key value for chemical safety assessment

Half-life in air:

10.3 h

Additional information

Since no experimental study is available investigating the phototransformation of the test item in air (Q)SAR modelling was applied (M-243077-01-1). AOPWIN estimates the rate constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals. The rate constants estimated by the program are used to calculate atmospheric half-lives for organic compounds based upon average atmospheric concentrations of hydroxyl radicals and ozone. The photochemical half-life of the test item in air was estimated by use of the AOPWIN, version 1.91. When the OH concentration is assumed to be 1.5E+06 radicals/cm³ (12 h day), for the reaction with evaporated compound in air, a half-life of 3.4 h (0.3 d) was calculated. The corresponding chemical lifetime is 4.9 h (0.4 d). When the OH concentration is assumed to be 0.5E+5 radicals/cm³ (24 h day), the half-life is 10.3 h (0.4 d) and the corresponding chemical lifetime is 14.8 h (0.6 d).