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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April-May 2001
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
according to guideline
Guideline:
ISO 9888 Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium - Static test (Zahn-Wellens method)
Deviations:
yes
Remarks:
no inoculum control used (reference substance e.g. ethylene glycol, aniline)
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: sewage treatment plant Trostberg
- Method of cultivation: aerobic cultivation, dry solids: 5.5g/L
Duration of test (contact time):
28 d
Initial conc.:
680 mg/L
Based on:
test mat.
Initial conc.:
ca. 400 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST CONDITIONS
- Composition of medium: activated sludge, nutrient medium, deionized water
- Additional substrate: nutrient medium (according to DIN EN 9888)
- Test temperature: 20-25°C
- pH adjusted: yes (to pH 7 +/- 0.5 if required)

TEST SYSTEM
- Culturing apparatus: brown glass vessels (2 L)
- Number of culture flasks/concentration: 1
- Method used to create aerobic conditions: aeration and agitation
- Measuring equipment: TOC Analyzer Elementar and pH-meter 691, Methrom, Herisau

SAMPLING
- Sampling frequency: at least every 4 days

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (1 replicate)
- Abiotic sterile control: yes (HgCl2 added, 1 replicate)
Reference substance:
other: no reference substance used
Preliminary study:
Not applicable.
Test performance:
No unusual observations during test affecting results.
Key result
Parameter:
% degradation (DOC removal)
Value:
10
Sampling time:
28 d
Details on results:
No further details reported.
Results with reference substance:
Not applicable, no reference substance tested.

Table 1: DOC removal [%]

     DOC removal [%]
 Date  Day  Test Vessel HgCl2 Vessel 
 24.04.2001  1  9  1
 26.04.2001 3 8  5
 30.04.2001   7  11  4
 04.05.2001   11  11  9
 08.05.2001  15   8  3
 11.05.2001  18  11  9
 15.05.2001  22  16  8
 18.05.2001  25  15  10
 21.05.2001  28  20  10
Validity criteria fulfilled:
not applicable
Remarks:
no test results with reference substance available (e.g. aniline, ethylene glycol)
Interpretation of results:
not inherently biodegradable
Conclusions:
TDI-Urone is not inherently biodegradable under the conditions of the test.
Executive summary:

TDI-Urone was tested for inherent biodegradability according to the German Guideline DIN EN ISO 9888 which is similar to OECD 302 B (Zahn-Wellens-Test) at an initial concentration of ca. 400 mg DOC/L at temperatures of 20 -25°C for 28 days. Biodegradation was followed by measurements of DOC removal.

Under the conditions of the test, 10 % degradation could be observed which indicates the potential for environmental persistence.

Endpoint:
biodegradation in water: ready biodegradability
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:

Description of key information

Under the conditions of the test guideline IN EN ISO 9888 which is similar to OECD 302 B (Zahn-Wellens-Test), 10 % degradation could be observed. This indicates the potential for environmental persistence.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

TDI-Urone was tested for inherent biodegradability according to the German Guideline DIN EN ISO 9888 which is similar to OECD 302 B (Zahn-Wellens-Test) at an initial concentration of ca. 400 mg DOC/L at temperatures of 20 -25°C for 28 days. Biodegradation was followed by measurements of DOC removal.

Under the conditions of the test, 10 % degradation could be observed which indicates the potential for environmental persistence.