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Environmental fate & pathways

Phototransformation in air

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Reference
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:
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:
1.22 h
Test condition:
calculation

rate constant of 3.15 *10-10cm3/(molecule*sec)

Conclusions:
In the atmosphere a half-life of 1.22 hours for MBTS due to reaction with photochemically produced hydroxyl radicals is estimated by AOPWIN v1.92 with a rate constant of 3.15 *10-10cm3/(molecule*sec).
Executive summary:

In the atmosphere a half-life of 1.22 hours for MBTS due to reaction with photochemically produced hydroxyl radicals is estimated by AOPWIN v1.92 with a rate constant of 3.15 *10-10cm3/(molecule*sec), considering an OH-concentration of 500,000 radicals/cm³ as a 24-h average (Currenta, 2010). The estimated half-life in air of MBTS is much shorter than 48 hours and hence no potential for long-range transport of MBTS in air is expected.

Description of key information

In the atmosphere a half-life of 1.221 hours for MBTS due to reaction with photochemically produced hydroxyl radicals is estimated by AOPWIN v1.92 with a rate constant of 3.15 *10-10 cm3/(molecule*sec), considering an OH-concentration of 500,000 radicals/cm³ as a 24-h average (Currenta, 2010). The estimated half-life in air of MBTS is much shorter than 48 hours and hence no potential for long-range transport of MBTS in air is expected.

Key value for chemical safety assessment

Half-life in air:
1.221 h
Degradation rate constant with OH radicals:
0 cm³ molecule-1 s-1

Additional information