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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:
2013-01-22 - 2013-02-21
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)
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Municipal activated sludge from the wastewater treatment plant of Mannheim, Germany.
The inoculum was collected on 21 January 2013 from the aeration tank of the plant and
aerated in the laboratory until use. A suitable aliquot of the activated sludge suspension
was sieved by a finely woven mesh with a mesh size about 1 mm. To reduce the content
of inorganic carbon in the blank controls the activated sludge was aerated with carbon
dioxide free air for about 24 hours at 22 ± 2° C.

At the day of exposure the suspension was washed one time with drinking water.
Therefore the aeration was stopped and the sludge was allowed to settle. After settling
the supernatant was discarded and the remaining sludge suspension was filled up with
drinking water and the concentration oft the sludge was adjusted to 6.0 g/L dry weight.
Aliquots of 7.5 mL were added to the test vessels to obtain an activated sludge
concentration of 30 mg/L dry weight.

Reason for the choice of the test system: The test guideline recommends the usage of
activated sludge from a wastewater treatment plant, treating municipal sewage.
Duration of test (contact time):
28 d
Initial conc.:
20 mg/L
Based on:
ThOD/L
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance:
aniline
Key result
Parameter:
% degradation (CO2 evolution)
Value:
10 - 20
Sampling time:
28 d
Details on results:
4.1. DEGREE OF BIODEGRADATION
Duration of the adaptation phase: 22 days
Degree of biodegradation of the test substance at the


Degree of biodegradation of the test substance at the end of exposure, mean value: 10-20 % CO2/ThCO2
Reference substance: aniline
Degree of biodegradation of the reference substance after 14 days: 79 % CO2/ThCO2
Degree of biodegradation in the inhibition control after 14 days: 41 % CO2/ThCO2
Test temperature: 22 ± 2° C

Test duration Test sample 1 Test sample 2   Test sample mean
[days]      
0 0 0 0
1 0 0 0
3 2 0 1
7 2 -1 1
10 4 1 3
14 6 2 4
17 8 3 6
21 13 5 9
24 17 6 12
27 22 8 15
28 29 10 20
Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
The conclusion that Amines, tri-C8-10-alkyl was not readily biodegradable in this carbon dioxide evolution test is based on the quantitative determination of the formed carbon dioxide in the test substance assays in comparison to the calculated maximal theoretical carbon dioxide production.
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:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
[Describe why the read-across can be performed (e.g. common functional group(s), common precursor(s)/breakdown product(s) or common mechanism(s) of action]

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
[Provide here, if relevant, additional information to that included in the Test material section of the source and target records]

3. ANALOGUE APPROACH JUSTIFICATION
[Summarise here based on available experimental data how these results verify that the read-across is justified]

4. DATA MATRIX
Reason / purpose:
read-across source
Key result
Parameter:
% degradation (CO2 evolution)
Value:
10 - 20
Sampling time:
28 d
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Based on data for a suitable read across substance, one can assume that Tridodecylamine is not readily biodegradable.

Description of key information

Not readily biodegradable: 10 - 20% in 28 days (OECD 301B, read across)

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information