p-cresol

Phototransformation in water

Link to relevant study record(s)

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.