Butyric acid

Phototransformation in air

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).