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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
Study type:
indirect photolysis
Principles of method if other than guideline:
rose bengal used as sensitizer for formation of singlet oxygen
GLP compliance:
not specified
Analytical method:
gas chromatography
high-performance liquid chromatography
Light source:
other: Sylvania 650W Type DWY tungsten-halogen lamp
Type of sensitiser:
water with additives
Details on sensitiser:
rose bengal leading to formation of 1O2 at:
Concentration of sensitiser:
4 other: 10E-14 molar
Duration:
2 h
Temp.:
19 °C
% Degr.:
50
Sampling time:
500 h
Test condition:
Indirect photolysis

INDIRECT PHOTOLYSIS due to 1O2 (singlet dioxygen)
- Rate constant: 1.1 E7 M-1 s-1 at pH 8.3
                 2.4 E7 M-1 s-1 at pH 8.8
                 1.6 E8 M-1 s-1 at pH 10
                 3.5 E8 M-1 s-1 at pH 11.5
- Half life t1/2: 500 h under noon summer sunlight(Switzerland) with 4E-14 M singlet oxygen

Validity criteria fulfilled:
not specified
Conclusions:
In the hydrosphere the cresols are expected to undergo photolytical degradation because of the presence of the aromatic ring which acts as a chromophore. By irradiation of solutions of p-cresol in a merry-go-round reactor, with rose bengal as a sensitizer, a half-life of 21 d in surface water under noon summer sunlight and the latitude of Switzerland was estimated.
Executive summary:

In the hydrosphere the cresols are expected to undergo photolytical degradation because of the presence of the aromatic ring which acts as a chromophore. By irradiation of solutions of p-cresol in a merry-go-round reactor, with rose bengal as a sensitizer, a half-life of 21 d in surface water under noon summer sunlight and the latitude of Switzerland was estimated.

Description of key information

In the hydrosphere a half-life of 21 d in surface water under noon summer sunlight and the latitude of Switzerland was estimated for p-cresol.

Key value for chemical safety assessment

Half-life in water:
21 d

Additional information

In the hydrosphere the cresols are expected to undergo photolytical degradation because of the presence of the aromatic ring which acts as a chromophore. By irradiation of solutions of p-cresol in a merry-go-round reactor, with rose bengal as a sensitizer, a half-life of 21 d in surface water under noon summer sunlight and the latitude of Switzerland was estimated.

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