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Diss Factsheets

Environmental fate & pathways

Phototransformation in air

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Endpoint:
phototransformation in air
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
no data
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Qualifier:
according to guideline
Guideline:
other: no guideline reported
Principles of method if other than guideline:
In the test, thiourea was adsorbed on silica gel and irradiated with light (290 nm). Volatile compounds, as well as CO2, were analysed after irradiation.
GLP compliance:
not specified
Light source:
not specified
Light spectrum: wavelength in nm:
290
Key result
% Degr.:
4.7
Test condition:
no data
Transformation products:
not specified
Validity criteria fulfilled:
not specified
Conclusions:
At a wavelength of 290 nm thiourea is degraded to 4.7 % (test duration not reported).
Executive summary:

In the test, thiourea was adsorbed on silica gel and irradiated with light (290 nm). Volatile compounds, as well as CO2, were analysed after irradiation.

At a wavelength of 290 nm thiourea is degraded to 4.7 % (test duration not reported).

Endpoint:
phototransformation in air
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
supporting study
Study period:
no data
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
secondary literature
Qualifier:
no guideline available
Principles of method if other than guideline:
Computer estimation of the Atmospheric gas-phase reaction rate of organic compounds with hydroxyl radicals and ozone.
GLP compliance:
not specified
Light source:
not specified
Validity criteria fulfilled:
not applicable
Conclusions:
The rate constant for the vapour-phase reaction of thiourea with photochemically-produced hydroxyl radicals has been estimated as 4.2X10-11 cu cm/molecule-sec at 25 °C using a structure estimation method, corresponding to an atmospheric half-life t1/2 of about 3 h at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm.
Executive summary:

Meylan & Howard conducted a computer estimation of the atmospheric gas-phase reaction rate of organic compounds with hydroxyl radicals and ozone.

The rate constant for the vapour-phase reaction of thiourea with photochemically-produced hydroxyl radicals has been estimated as 4.2X10-11 cu cm/molecule-sec at 25 °C using a structure estimation method, corresponding to an atmospheric half-life t1/2 of about 3 h at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm.

Endpoint:
phototransformation in air
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
no data
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
secondary literature
Qualifier:
according to guideline
Guideline:
other: GSF Test on photodegradation
GLP compliance:
not specified
Light source:
not specified
Transformation products:
not specified
Validity criteria fulfilled:
not specified
Conclusions:
Thiourea is photochemically degraded to 0.23 % (test duration not reported).
Executive summary:

Under the conditions of the GSF test, Schmidt-Bleek et al. (1982) report that thiourea is photochemically degraded to 0.23 % (test duration not reported).

Description of key information

An atmospheric half-life t1/2 of about 3 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm is reported for thiourea.

Key value for chemical safety assessment

Half-life in air:
3 h

Additional information

Available literature on phototransformation of thiourea in air reports that the substance is degraded from 0.23% to 4.7% under the conditions of the GSF test (Schmidt-Bleek et al., 1982) and when irridiated at a wavelength of 290 nm (Freitag et al., 1985), respectively. The total test duration for these two experiments is however unknown.

In addition, Meylan & Howard (1993; as cited in the Hazardous Substances Data Bank) determined an atmospheric half-life t1/2 of about 3 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm.