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Environmental fate & pathways

Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
December 12, 2006 - February 26, 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
adopted July 17, 1992
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Version / remarks:
July 31, 1992
Deviations:
no
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was resuspended in tap water and again centrifuged. This procedure was repeated twice. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 1.5 g dry material per litre were mixed with test water and then aerated until use overnight.
Duration of test (contact time):
28 d
Initial conc.:
102 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Temperature: 22°C
Light conditions: darkness
pH: 7.6 (start), 7.7 - 7.9 (end)

The amounts of test item and reference item were directly weighed into the test flasks. No emulsifiers or solvents were used, but the solutions were dispersed by stirring to achieve a homogeneous solution of the test item. The closed test flasks were incubatd in a climatised room under contiuous stirring.
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
-6
Sampling time:
28 d
Details on results:
Under the test conditions no biodegradation of the test item could be observed.
Results with reference substance:
The reference item sodium benzoate was sufficiently degraded to 87 % after 14 days and to 90 % after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum.
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The test item is not considered to be readily biodegradable.
Executive summary:

The informtion for this endpoint study record was obtained from an experimental study. The OECD GLP criteria were met and the methods applied are fully compliant with OECD TG 301F.

The test item is not considered to be readily biodegradable.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
For this endpoint information from structural similar compounds is available. The studies for these similar compounds were performed according to GLP and the methods applied are fully compliant with OECD TG 301F. See chapter 13 report for a more detailed justification.
Reason / purpose:
read-across source
Key result
Parameter:
% degradation (O2 consumption)
Value:
-6
Sampling time:
28 d
Interpretation of results:
not readily biodegradable

Description of key information

There ais no study on biodegradability performed with the test item available. However, a sufficient and reliable study according OECD Guideline 301F conducted with a structural analogue substance is available. Therefore, the test item is considered to be not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information