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Environmental fate & pathways

Phototransformation in air

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Endpoint:
phototransformation in air
Data waiving:
other justification
Justification for data waiving:
other:
Endpoint:
phototransformation in air
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
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
Justification for type of information:
QSAR prediction:Model considered valid by OECD
Qualifier:
no guideline required
Principles of method if other than guideline:
QSAR model, EPI Suite v 4.1/Aopwin v1.92
GLP compliance:
no
Remarks:
not applicable
Estimation method (if used):
PHOTOCHEMICAL REACTION WITH OH RADICALS - assumed reaction conditions used in model:
- Concentration of OH radicals:1.5E6 per cm3
- Temperature for which rate constant was calculated: 25C
- Computer programme: AOPWIN v1.92
Light source:
sunlight
Preliminary study:
Using the AOPWIN QSAR model, the photochemical degradation rate of Talc (Mg3H2(SiO3)4) in the atmosphere is 6.9000 E-12 cm3/molecule-sec, with a resultant predicted half live of 18.602 Hrs ( 1.550 Days (12-hr day; 1.5E6 OH/cm3))
OVERALL OH Rate Constant = 6.9000 E-12 cm3/molecule-sec
HALF-LIFE = 1.550 Days (12-hr day; 1.5E6 OH/cm3)
HALF-LIFE = 18.602 Hrs


Reaction with:
OH radicals
Rate constant:
0 cm³ molecule-1 s-1
Transformation products:
no
Results with reference substance:
OVERALL OH Rate Constant = 6.9000 E-12 cm3/molecule-sec
HALF-LIFE = 1.550 Days (12-hr day; 1.5E6 OH/cm3)
HALF-LIFE = 18.602 Hrs




Hydrogen Abstraction      =  0.0000 E-12 cm3/molecule-sec

Reaction with N, S and -OH =  6.9000 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 = 6.9000 E-12 cm3/molecule-sec

HALF-LIFE = 1.550 Days (12-hr day; 1.5E6 OH/cm3)

HALF-LIFE = 18.602 Hrs

Validity criteria fulfilled:
yes
Remarks:
The photochemical degradation rate of Calcium dodecylbenzenesulphonate in the atmosphere is 32.4364 E-12 cm3/molecule-sec, with a resultant predicted half live of 3.957 Hrs ( 0.330 Days (12-hr day; 1.5E6 OH/cm3))
Conclusions:
Using the AOPWIN QSAR model, the photochemical degradation rate of Talc (Mg3H2(SiO3)4) in the atmosphere is 6.9000E-12 cm3/molecule-sec, with a resultant predicted half live of 18.602 Hrs ( 1.550 Days (12-hr day; 1.5E6 OH/cm3))
Executive summary:

Using the AOPWIN QSAR model, the photochemical degradation rate of Talc (Mg3H2(SiO3)4) in the atmosphere is 6.9000 E-12 cm3/molecule-sec, with a resultant predicted half live of 18.602 Hrs ( 1.550 Days (12-hr day; 1.5E6 OH/cm3))

Description of key information

Talc (Mg3H2(SiO3)4) has low vapor pressure ( 1.48E-020 Pa) indicating significant amounts of Talc (Mg3H2(SiO3)4) are unlikely to be present in the atmosphere for photodegradation. If released to air, a vapor pressure of 1.11E-022 mm Hg  at 25 deg C (1.11E-022 mm Hg is equivalent to a vapour pressure of 1.48E-020 Pa) indicates significant amounts of Talc (Mg3H2(SiO3)4) are unlikely to be present in the atmosphere for photodegradation and therefore Talc (Mg3H2(SiO3)4) is not expected to be susceptible to direct photolysis by sunlight. 

Using the AOPWIN QSAR model, the photochemical degradation rate of Talc (Mg3H2(SiO3)4) in the atmosphere is 6.9000 E-12 cm3/molecule-sec, with a resultant predicted half live of 18.602 Hrs ( 1.550 Days (12-hr day; 1.5E6 OH/cm3))

Key value for chemical safety assessment

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

Additional information

Talc (Mg3H2(SiO3)4) has low vapor pressure ( 1.48E-020 Pa) indicating significant amounts of Talc (Mg3H2(SiO3)4) are unlikely to be present in the atmosphere for photodegradation. If released to air, a vapor pressure of 1.11E-022 mm Hg  at 25 deg C (1.11E-022 mm Hg is equivalent to a vapour pressure of 1.48E-020 Pa) indicates significant amounts of Talc (Mg3H2(SiO3)4) are unlikely to be present in the atmosphere for photodegradation and therefore Talc (Mg3H2(SiO3)4) is not expected to be susceptible to direct photolysis by sunlight. 

Using the AOPWIN QSAR model, the photochemical degradation rate of Talc (Mg3H2(SiO3)4) in the atmosphere is 6.9000 E-12 cm3/molecule-sec, with a resultant predicted half live of 18.602 Hrs ( 1.550 Days (12-hr day; 1.5E6 OH/cm3))