Hydrocarbons, C12-C18, isoalkanes, cyclics, 2-30% aromatics

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:

other: Results obtained for representative components of the substance, by calculations with a valid QSAR

Justification for type of information:

Standard photolysis studies are not applicable to petroleum UVCB substances, therefore in accordance with Annex XI Section 1.3 testing is not scientifically necessary and the endpoint has been fulfilled using QSAR calculations for relevant constituents. The use of QSAR in this instance is justified because:
- the results are obtained from a QSAR model whose scientific validity has been established

Guideline:

other: Reach guidance on QSAR - R.6

Deviations:

no

Principles of method if other than guideline:

The phototransformation in air of representative constituents of the substance was calculated using AOPWIN v.1.92

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
No test surrogate

Estimation method (if used):

The phototransformation rates and half-lives were calculated using AOPWIN v1.92

Light source:

other: calculated data

Details on light source:

Calculated data

Details on test conditions:

Theoretical conditions applied to calculations:
- 25°C
- 12 hrs day
- 1.5 x 10^6 OH/cm3

Reference substance:

no

Preliminary study:

No preliminary study

Test performance:

Not applicable

Key result

DT50:

>= 0.09 - <= 2.38 d

Test condition:

Range calculated for the selected constituents

Key result

Reaction with:

OH radicals

Rate constant:

>= 0 - <= 0 cm³ molecule-1 s-1

Transformation products:

not specified

Results with reference substance:

Not applicable

Conclusions:

The half-lives of selected constituents of Hydrocarbons, C12-C18, isoalkanes, cyclics 2-30% aromatics were in the range 0.09 and 2.38 d.

Executive summary:

This substance is a UVCBs. Therefore, the phototransformation in air was estimated from the AOPWIN v1.92 calculations of phototransformation of selected hydrocarbons likely to be constituents of this substance as identified by PETRORISK.

 

The phototransformation rate for this substance is in the range 4.50 x 10^-12 and 1.19 x 10 ^-10 cm3/molecule/sec. The half-lives of selected constituents of hydrocarbons, C12 -C18, isoalkanes, cyclics 2 -30% aromatics were in the range 0.09 and 2.38 d.

Description of key information

This substance is a hydrocarbon UVCBs and the constituent hydrocarbons will exhibit a wide range of photolysis in air values. Standard tests for this endpoint are intended for single substances and are not appropriate for these complex substances as the composition of the total dissolved hydrocarbons will be different from the composition of the parent substance. However, this endpoint is characterized using quantitative structure property relationships for representative hydrocarbon structures that comprise the hydrocarbon blocks used to assess the environmental risk of these substances with the PETRORISK model (see Product Library in PETRORISK spreadsheet attached in section 13). The potential constituents identified by PETRORISK that match the composition of this substance were used to run the AOPWIN model.

 

The phototransformation rate for this substance is in the range 4.50 x 10^-12 and 1.19 x 10 ^-10 cm3/molecule/sec. The half-lives of selected constituents of hydrocarbons, C12 -C18, isoalkanes, cyclics 2 -30% aromatics were in the range 0.09 and 2.38 d.