Mixed LOF

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil: simulation testing

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:

Standard biodegradation 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. Full justifications for this QSAR are
presented in 'Attached justification', but in brief these are justified because:
- the results are obtained from a QSAR model whose scientific validity has been established
- petroleum substances fall within the applicability domain of the QSAR model
- results are adequate for the purposes of risk assessment
- adequate and reliable documentation is provided

Data source

Reference

Reference Type:

other: Computer model

Title:

BioHCWin v1.01a

Author:

Howard et al

Year:

2010

Bibliographic source:

Howard, P.H., W.M., Meylan, Aronson, D., Stiteler,W.M., Tunkel, J., Comber, M. and Parkerton, F. 2005. A New Biodegradation Prediction Model Specific to Petroleum Hydrocarbons. Environ. Toxicol. Chem. 24(8): 1847-1860.

Materials and methods

Principles of method if other than guideline:

- Software tool(s) used including version: EPISuite v4.10
- Model(s) used: BioHCWin v1.01a
- Model description: see field 'Attached justification'
- Justification of QSAR prediction: see field 'Attached justification'

Test material

Test material information

Constituent 1

Reference substance name:

Mixed LOF

IUPAC Name:

Mixed LOF

Details on test material:

Used composition of Mixed LOF from Section 1 to input into Petrotox model

Results and discussion

Half-life / dissipation time of parent compound

DT50:

>= 3.5 - <= 38.4 d

Temp.:

20 °C

Remarks on result:

other:

Remarks:

Multiple results Calculated degradation half-lives for constituents of this substance range b etween 3.5 - 38.4 days. It should be borne in mind that this is the full range of predicted valu es, and that this may be misleading or unrepresentative of the properties of the UVCB substance as a whole. The range should therefore be treated with caution and not taken out of context. The substance is a hydrocarbon UVCB. Standard tests for this endpoint are intended for single sub stances and are not appropriate for this complex substance. However, this endpoint is characterised using quantitative structure property relationships for representative hydrocarbon structures that comprise the hydrocarbon blocks used to assess the environmental risk of this substance with the PETRORISK model (see Product Library in PETRORISK spreadsheet attached in IUCLID section 13). For purposes of PBT assessment, the substance has been assessed using a combination of QSAR predictions and confirmatory experimental testing for representative constituents using a hyd rocarbon block approach. For details see report titled 'Evaluation of PBT for Petroleum Substances' in IUCLID section 13.

Transformation products:

not specified

Remarks:

potential metabolites of aerobic biodegradation and their relative concentrations are estimated using the Kinetic 301F model in the OASIS/LMC Catalogic software (v5.11.19).

Details on transformation products:

Detailed information including representative structures, phys-chem properties, estimated quantities , and QSAR predictions of primary and ultimate degradation of the identified metabolites as well as an assessment of their PBT and vPvB potential is contained in the file "Framework for Assessing Metabolites for Hydrocarbon Solvent UVCBs" and is attached in "Attached Background Material" below.

Predicted metabolite structures, abundance, and PBT property assessments are contained in full in the file "Alkenes_C6_C12_HF_products_Metabolite ID and Assessment.xlsx" and are atached in the "Full Study report" section below.

Applicant's summary and conclusion

Conclusions:

Given the predicted primary half-lives in water, soil, and sediment compartments for the parent constituents and the associated PBT assessment for the predicted metabolites identified, it is concluded that the substance is not persistent, and as such simulation studies in soil or sediment are not required and will not provide additional information as to the PBT/vPvB properties of the substance or its metabolites.

Executive summary:

Given the predicted primary half-lives in water, soil, and sediment compartments for the parent constituents and the associated PBT assessment for the predicted metabolites identified, it is concluded that the substance is not persistent, and as such simulation studies in soil or sediment are not required and will not provide additional information as to the PBT/vPvB properties of the substance or its metabolites.