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Diss Factsheets

Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

biodegradation in water: ready biodegradability
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Review report, peer-reviewed data, secondary literature, acceptable for assessment

Data source

Reference Type:
review article or handbook
European Union Risk Assessment Report - Benzene - Final approved version
Bibliographic source:
benzenereport063.pdf from web site

Materials and methods

Principles of method if other than guideline:
Several biodegradation studies are summarised in the EU report. In these studies different test methods are used. Among others, tests are performed according to OECD test guideline 301 C, D and F and 302 B.
GLP compliance:

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Details on test material:
- Name of test material (as cited in study report): benzene

Study design

Oxygen conditions:
Inoculum or test system:
other: inoculum was according to the respective test guidelines
Details on inoculum:
not applicable (review)

Results and discussion

% Degradation
Key result
% degradation (TOC removal)
> 4 - <= 100
Sampling time:
56 d

Any other information on results incl. tables

In several tests on ready biodegradation, a great variation in results was obtained. In some tests complete mineralization (100´% biodegradation) was observed, while in other tests almost no degradation (4 - 10% biodegradation) was found. Criteria on ready biodegradability according to OECD test guideline 301 (60/50% biodegradation within the 10 day window) were met in some tests but not in others.


If more than one screening test result is available, positive results should be considered for assessment purposes, irrespective of negative results, if the scientific quality is good and the test conditions are well documented. As this is the case for the studies that show ready biodegradation of benzene, benzene consequently will be classified as readily biodegradable.

Applicant's summary and conclusion

Interpretation of results:
readily biodegradable
In different ready biodegradation tests according or similar to OECD test guidelines, deviating results on the biodegradation of benzene were observed (biodegradation from ca. 4 to 100%). In some tests benzene was readily biodegradable but not in others.
If positive and negative results are available, the positive results should be considered for assessment purposes, when the scientific quality is good and the test conditions are well documented. This is the case for benzene and benzene consequently is assessed as readily biodegradable.