Registration Dossier
Registration Dossier
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EC number: 201-944-8 | CAS number: 89-83-8
Phototransformation in air
Administrative data
Link to relevant study record(s)
- Endpoint:
- phototransformation in air
- Type of information:
- calculation (if not (Q)SAR)
- Remarks:
- estimated by calculation
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Accepted calculation method.
- Principles of method if other than guideline:
- Calculated with AOP Program v1.92 of EPI-Suite Software. The Atmospheric Oxidation Program (AOPWIN) estimates the rate constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals. The rate constants are then used to calculate atmospheric half-lives for organic compounds based upon average atmospheric concentrations of hydroxyl radicals and ozone.
- GLP compliance:
- no
- Estimation method (if used):
- PHOTOCHEMICAL REACTION WITH OH RADICALS
- sensitiser for indirect photolysis: OH radicals
- Concentration of OH radicals: 0.5 E6 OH/cm³, 24 h/d - % Degr.:
- 50
- Sampling time:
- 3.6 h
- Executive summary:
In the atmosphere a half-life of 3.6 h for thymol is estimated due to reaction with photochemically produced hydroxyl radicals, considering an OH-concentration of 500,000 radicals/cm³ as a 24-h average (Currenta, 2010).
Reference
A 24-hour day and an OH radical concentration of 0.5 E06 OH/cm³ are assumed for the calculation.
Rate constant (for indirect photolysis): 0.000000000107 cm³/(molecule*sec)
Description of key information
In the atmosphere a half-life of 3.6 h for thymol is estimated due to reaction with photochemically produced hydroxyl radicals, considering an OH-concentration of 500,000 radicals/cm³ as a 24-h average (Currenta, 2010).
Key value for chemical safety assessment
Additional information
As no data on phototransfromation in air are available, the rate constant for the atmospheric gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals is estimated with the Atmospheric Oxidation Program (AOPWIN) of US Environmental Protection Agency. Since the estimated half-life of thymol in air is much shorter than 48 h, no potential of long-range transport of thymol is expected.
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