Hydrocarbons, C3-6, C5-rich, steam-cracked naphtha

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:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

EPISuite and the AOPWIN models are well documented and commonly used QSARs for predicting the potential indirect photolysis of chemicals in the atmosphere. Constituents within LOA streams fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.

Reason / purpose for cross-reference:

assessment report

Reason / purpose for cross-reference:

(Q)SAR model reporting (QMRF)

Principles of method if other than guideline:

The Atmospheric Oxidation Program for Microsoft Windows (AOPWIN) estimates the rate constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals. It also estimates the rate constant for the gas-phase reaction between ozone and olefinic/acetylenic compounds. The rate constants estimated by the program are then used to calculate atmospheric half-lives for organic compounds based upon average atmospheric concentrations of hydroxyl radicals and ozone. The author used data from other investigators. This data was generated using two methods: absolute and relative constant techniques. The author then applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.

Key result

DT50:

>= 0.056 - <= 5.88 d

Test condition:

Overall OH half-lives in 12-h daylight

Remarks on result:

other: QSAR predicted value

Details of the constituents and how their overall OH half-live predictions relate to the persistence assessment are found in the AOPWIN QMRF/QPRF and in the Persistence Weight of Evidence Evaluation (see cross-references).

Conclusions:

The predicted OH half life of the constituents in the category range between 0.056 and 5.88 days.

Executive summary:

The indirect photolysis half-life was predicted using AOPWIN from the EPISUITE v4.11 program and the methodology described by Atkinson et al. (1985). The predicted OH half life of the measured constituents of the category (at equal or above 0.1% w/w) range between 0.056 and 5.88 days, considering 12-h daylight.

Description of key information

The indirect photolysis half-life was predicted using AOPWIN from the EPISUITE v4.11 program and the methodology described by Atkinson et al. (1985). The predicted half life of the measured constituents of the category (at equal or above 0.1% w/w) range between 0.056 and 5.88 days, considering 12-h daylight.