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Environmental fate & pathways

Phototransformation in water

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Reference
Endpoint:
phototransformation in water
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
Non-GLP non-guideline experimental study, published in peer reviewed literature, notable limitations in design and/or reporting, but adequate for assessment
Study type:
direct photolysis
Principles of method if other than guideline:
Aliquots of 15 ml 1.00 ppm solution were placed in quartz tubes, which were placed horizontally on a tray on the roof of the laboratory.
The tubes were washed once a week during the entire experiment. Tubes were removed periodically for analysis by a hollow fiber-mass spectroscopic method.
GLP compliance:
no
Radiolabelling:
no
Analytical method:
other: hollow fiber-mass spectroscopy
Light source:
sunlight
Type of sensitiser:
not specified
Details on test conditions:
15 ml of the test solution was placed in 22-mm i.d. x 53-mm quartz tubes. The ice cooled tubes, previously constricted at the neck, were sealed. The tubes were placed horizontally on a tray on the roof of the laboratory. The tubes were washed once a week during the entire experiment to remove soot and (or) snow and shaken once a week during the entire year. The temperature range of these tube was estimated to be between -20 and 40 oC. Tubes were removed periodically for analysis.
Duration:
1 yr
Initial conc. measured:
1 mg/L
Dark controls:
yes
Key result
% Degr.:
>= 70 - < 79
Sampling time:
1 yr
Test condition:
outdoor exposure
Rate constant (for indirect photolysis):
0.105 other: month-1
Key result
DT50:
6.6 mo
Test condition:
outdoor conditions
Transformation products:
not specified
Conclusions:
Trichloroethylene (1 mg/l) in water was degraded by 52-56% after one year in the dark and by 70-79% in the presence of sunlight.

Description of key information

Degradation of trichloroethylene in water by photolysis is slow, with a half-life of 201 days (6.6 month)

Key value for chemical safety assessment

Half-life in water:
201 d

Additional information

Photolysis is not likely to be a significant removal process for trichloroethylene.

Trichloroethylene (1 mg/l) in water was degraded by 52-56% after one year in the dark and by 70-79% in the presence of sunlight (Dilling et al., 1975).

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