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Administrative data

biodegradation in soil: simulation testing
Type of information:
Adequacy of study:
key study
Study period:
March 31 2020
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 simulation biodegradation studies are not possible for petroleum UVCB substances. 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 Type:
other: Computer model
BioHCWin v1.01a
Howard et al
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

Test guideline
no guideline required
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

Constituent 1
Chemical structure
Reference substance name:
Hydrocarbons, C7-C9, isoalkanes
EC Number:
Cas Number:
Molecular formula:
None available - not a single isomer - see remarks
Hydrocarbons, C7-C9, isoalkanes

Results and discussion

Half-life / dissipation time of parent compound
>= 5.7 - <= 8.91 d
20 °C
Remarks on result:
other: QSAR result
Calculated degradation half-lives for constituents of this substance range between 5.7 - 8.91 days. It should be borne in mind that this is the full range of predicted values, 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 simulation studies for this endpoint are intended for monoconstituent substances and are not possible 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 hydrocarbon block approach. For details see report titled 'Evaluation of PBT for Petroleum Substances' in IUCLID section 13.
Transformation products:
not specified

Applicant's summary and conclusion