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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: screening tests
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: QSAR calculation, acceptable with restrictions

Data source

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

Materials and methods

Principles of method if other than guideline:
BioCHwin v1.01 in EPISuite 4 (2009). BioHCwin is a predictive model for determining quantitative primary biodegradation half-lives for individual petroleum hydrocarbons.  This model uses a fragment-based approach that is similar to several other biodegradation models, such as those within the Biodegradation Probability Program (Biowin) estimation program.  A half-life in days is estimated using a multiple linear regression against counts of 31 distinct molecular fragments.  The model was developed using a data set consisting of 175 compounds with environmentally-relevant experimental data that was divided into training and validation sets.  
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Not applicable
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):Not applicable

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
other: Not applicable
Details on inoculum:
Not applicable
Details on study design:
Not applicable

Results and discussion

Preliminary study:
Not applicable
Test performance:
Not applicable
% Degradation
Parameter:
not specified
Value:
50
Sampling time:
3.5 d

BOD5 / COD results

Results with reference substance:
Not applicable

Applicant's summary and conclusion

Validity criteria fulfilled:
not applicable
Remarks:
QSAR
Interpretation of results:
readily biodegradable
Conclusions:
The results for butane indicate a BIOHCWIN (1/2 life in days) of 3.5 days
Executive summary:

Members of this category are gases at standard temperature and pressure, so conducting a standard ready biodegradability test is technically difficult and based on exposure estimates the test may not be relevant. In addition, it is difficult to assess the persistence of UVCB streams using standard test methods as the tests measure the properties of the whole substance but do not provide information on the individual components. Instead, it is more appropriate to consider whether the representative components of these streams are persistent.

Therefore, the use of a QSAR to predict the biodegradability of representative components of these streams is an appropriate technique to use a part of a weight of evidence approach. The use of BioHCwin is appropriate for this Category as these streams falls within the applicability domain of the model.