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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
22 June - 2 August 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
The sludge was taken from the activation basin of the sewage treatment plant, In den Seewiesen, 67480 Edenkoben.
Date of collection: 29. Jun. 2018, batch no: 20180629
The sludge was filtrated, washed with test medium (2x) and re-suspended in test medium. It was then aerated until use. The dry matter was determined to contain 4060 mg of suspended solids/L.
Duration of test (contact time):
<= 28 d
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance:
aniline
Test performance:
The test item was tested using a concentration of nominally 20 mg organic carbon/L test item in test medium following OECD 301B and EU-Method C.4-C.
Aniline was chosen as positive control.
Activated sludge was used as inoculum (concentration in the test 25.0 mg dry matter/L). The test was left running for 28 days.
Key result
Parameter:
% degradation (CO2 evolution)
Value:
6.2
Sampling time:
28 d
Details on results:
Degradation values in %

Day Positive Positive Positive Test1 Test2 Test Abiotic Toxicity
Control 1 Control 2 Control Mean Control Control
Mean
2 1.0 -1.3 -0.1 -0.8 1.1 0.2 0.8 -0.7
4 6.1 10.0 8.1 1.0 -0.5 0.2 1.1 8.0
7 38.4 31.2 34.8 2.2 0.1 1.2 0.8 18.4
9 67.7 50.5 59.1 3.5 0.5 2.0 0.7 26.2
11 73.7 59.7 66.7 5.1 1.8 3.5 0.4 31.1
14 75.1 64.4 69.8 3.3 2.1 2.7 0.2 31.7
18 75.0 67.1 71.0 4.6 1.7 3.1 -0.2 33.5
23 81.9 77.1 79.5 4.9 4.6 4.7 0.4 34.8
29 78.7 73.7 76.2 4.0 8.3 6.2 0.1 35.7
Results with reference substance:
76.2% after 28 days
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The degree of biodegradation reached 6 % after 28 days.
Executive summary:

The degree of biodegradation reached 6 % after 28 days. The 10-day-window was not detected.

Because the test item is a mixture, the 10-day window has not to be taken into account. Degradation missed 60 % within 28 days, too. Therefore, regardless of the 10-day-window the test item is considered as “not readily biodegradable"within 28 days”.

The abiotic degradation reached 0.1 %.

Description of key information

The degree of biodegradation reached 6 % after 28 days. Degradation missed 60 % within 28 days.

The test item is considered as “not readily biodegradable" within 28 days”.

Key value for chemical safety assessment

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

Additional information