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Phototransformation in air

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phototransformation in air
Type of information:
Adequacy of study:
key study
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
Justification for type of information:
QSAR prediction
Principles of method if other than guideline:
Calculation based on AOPWIN v1.92, Estimation Programs Interface Suite™ for Microsoft® Windows v 4.10. US EPA, United States Environmental Protection Agency, Washington, DC, USA.
GLP compliance:
Estimation method (if used):
- Concentration of OH radicals: 0.5E+6 OH/cm³
- Degradation rate constant: 172E-12 cm³/mol×sec
- Computer programme: SRC AOP v1.92
Details on test conditions:
Sensitiser (for indirect photolysis): OH
Sensitiser concentration: 500,000 molecules/cm³
Key result
2.23 h
Test condition:
(24-hr day; SRC AOP v1.92)
Transformation products:
not specified

For detailed description on the model and its applicability, see "Any other information on materials and methods incl. tables". The estimation is based on a 24 hour day.

Validity criteria fulfilled:

Description of key information

After evaporation or exposure to the air, Disodium dihydrogen ethylenediaminetetraacetate will be rapidly degraded by photochemical processes.

Key value for chemical safety assessment

Half-life in air:
2.23 h
Degradation rate constant with OH radicals:
0 m³ molecule-1 s-1

Additional information

No experimental studies investigating the phototransformation of Disodium dihydrogen ethylenediaminetetraacetate (CAS 139-33-3, EDTA-Na2H2) in air is available. A QSAR calculation using AOPWIN v1.92 indicates, that EDTA-Na2H2 is susceptile to indirect photodegradation in air. The estimated half time for the reaction with OH-radicals is calculated to be 2.23 h (24h day; OH-concentration: 0.5E+06 OH/cm3). However, photodegradation is not considered to be an important environmental fate process since the substance is not expected to evaporate into the atmosphere due to the low vapor pressure.