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Environmental fate & pathways

Phototransformation in air

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phototransformation in air
Type of information:
Adequacy of study:
key study
1 (reliable without restriction)
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
Principles of method if other than guideline:
SRC AOP v1.92
GLP compliance:
Estimation method (if used):
- Concentration of OH radicals: 500000
- Degradation rate constant: 0.0000000000018143 cm³/molecule-sec
- Temperature for which rate constant was calculated: 25 °C
- Calculated t 1/2 is based on a 24 h day
8.8 d
Remarks on result:
other: the substance is within the applicability domain of the model (see attched QPRF)
Reaction with:
OH radicals
Rate constant:
0 cm³ molecule-1 s-1

AOP Program (v1.92) Results:
MOL WT : 72.11
------------------- SUMMARY (AOP v1.92): HYDROXYL RADICALS (25 deg C) --------
Hydrogen Abstraction = 1.8143 E-12 cm3/molecule-sec
Reaction with N, S and -OH = 0.0000 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 = 0.0000 E-12 cm3/molecule-sec
Addition to Fused Rings = 0.0000 E-12 cm3/molecule-sec
OVERALL OH Rate Constant = 1.8143 E-12 cm3/molecule-sec
HALF-LIFE = 8.843 Days (24-hr day; 0.5E6 OH/cm3)
HALF-LIFE = 212.230 Hrs

After evaporation or exposure to air the product will be slowly degraded by photochemical processes (DT50 = 8.8 d)

Description of key information

After evaporation or exposure to the air, the product will be slowly degraded by reaction with OH radicals.

Key value for chemical safety assessment

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

Additional information

In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met.

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.


For the assessment of the test item (Q)SAR results were used for photodegradation in air. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.


Therefore, further experimental studies on photodegradation in air are not provided.


Based on a EPISuite calculation with the model AOPWIN v1.92, the test item is indirectly photodegraded by reaction with hydroxyl radicals in the atmosphere with a half-life (t1/2) of about 8.8 days taking into account a 24-h day and a mean OH radical concentration of 0.5E06 radicals per cm³. The degradation rate constant was calculated to be 1.8143e-12 cm³/molecule*s.