Registration Dossier
Registration Dossier
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 202-851-5 | CAS number: 100-42-5
Phototransformation in water
Administrative data
Link to relevant study record(s)
- 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
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Hydrogen peroxide is cleaved by photolysis and the indirect photchemical degradation through OH radicals is measured using gas chromatography.
- GLP compliance:
- no
- Radiolabelling:
- no
- Analytical method:
- gas chromatography
- other: Photospectroscopy
- Light source:
- other: pressure mercury lamp
- Light spectrum: wavelength in nm:
- > 290
- Details on light source:
- Philips HPK 125 W high pressure mercury lamp
- Type of sensitiser:
- OH radical
- DT50:
- 237 d
- Transformation products:
- not specified
- Validity criteria fulfilled:
- not applicable
- Executive summary:
Styrene was tested for phototransformation in water. The Rate constant was determined to be 3.37 x 10^9 cm3 • molecule-1• s-1, the half live is 237 d.
Reference
A relative rate method was used to determine the degradation of styrene by OH radicals in water, produced by the photolysis of H2O2.
Table: Relative OH- and RO2 -radical reaction rate constant and half-life:
| KOH | K[RO2] | τ (Tage) |
Styrene | 3.37 x 109 | ~ 0.1 | 400 |
The relative rate constant was 3.37 x 10^9. Correcting this for an OH concentration of 10^-17 mol/L, this produces a half-life of 237 days for this degradation route (BUA, 1990).
Description of key information
A half-live of 237 d can be estimated in Mansour (1985).
Key value for chemical safety assessment
- Half-life in water:
- 237 d
Additional information
Styrene does not adsorb solar radiation appreciably at wavelengths greater than 300 nm, therefore degradation of styrene by direct photolysis is unlikely. Mansour (1985) studied the indirect photolysis of styrene in water by reaction with hydroxyl radicals. Using the observed relative rate constant and assuming an OH-concentration of 10 E-17 mol/L a half-life of 237 days can be estimated. Indirect photolysis is therefore not a relevant degradation process in water in comparison to volatilisation and biotransformation.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
