Registration Dossier

Environmental fate & pathways

Phototransformation in air

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
phototransformation in air
Type of information:
(Q)SAR
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:
(Q)ASR calculations, calculation program EPA EPI-Suite, component AOP Program v1.92
Estimation method (if used):
PHOTOCHEMICAL REACTION WITH OH RADICALS
- Concentration of OH radicals: 0.5 E6 OH/cm3 (average concentration for a 24 hr day)
- Degradation rate constant: overall OH rate constant = 2.6977 E-12 cm3/(molecule x sec)
- Temperature for which rate constant was calculated: 25°C
- Computer programme: AOP v 1.92 (US EPA/Syracuse Research Corporation)
Key result
DT50:
187.81 h
Test condition:
calculated value, based on a 24 hr day, temp. 25°C (DT50 = 7.825 d)
Validity criteria fulfilled:
not applicable
Remarks:
calculation method
Conclusions:
The photolytic half-life of butyric acid was calculated to be 7.825 days (based on an estimated OH rate constant derived from the structure of the test substance; sensitiser for indirect photolysis: OH; 0.5 E06 OH/cm³, 24-h day).
Executive summary:

The degradation of butyric acid in air by reaction with OH-radicals was estimated with the AOP program (v1.92) of US EPA EPI Suite v4.00. The overall OH rate constant was estimated to be 2.6977 E-12 cm³/(molecule*sec) based on the structure of the test compound. Using this rate constant and a 24-h day with an average OH radical concentration of 0.5 E06 OH/cm³, a half-life of approx. 188 hours was calculated (equivalent to 7.8 days) (ECT, 2009).

Description of key information

A half-life of approx. 188 hours (7.8 days) was calculated for the degradation of butyric acid in air by the reaction with OH-radicals (ECT, 2009).

Key value for chemical safety assessment

Half-life in air:
8 d

Additional information

The degradation of butyric acid in air by reaction with OH-radicals was estimated with the AOP program (v1.92) of US EPA EPI Suite v4.00. Using an estimated rate constant of 2.6977 E-12 cm³/(molecule*sec) and a 24-h day with an average OH radical concentration of 0.5 E06 OH/cm³, a half-life of approx. 188 hours was calculated (equivalent to 7.8 days) (ECT, 2009).