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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:
From June 17, 2010 to July 23, 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Samples of secondary effluent were obtained as the test inoculum from a sewage plant treating predominantly domestic sewage. Aerobic conditions were maintained in the effluent by aeration from a laboratory supply of oil-free compressed air.
- Sludge: 0.6 mL/L
Duration of test (contact time):
28 d
Initial conc.:
2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
other: ratio of BOD and either ThOD or COD
Details on study design:
Four groups: inoculum control, test, reference control and toxicity control
Reference substance:
benzoic acid, sodium salt
Preliminary study:
ThOD (NH3) of the test substance and reference substance: 2.71 and 1.67 mg O2/mg, respectively.
Test performance:
Test solution prepared in an inorganic salts medium
Closed bottles
In the dark
Temperature of ca. 20°C
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
divided by ThOD*100
Value:
0
Sampling time:
28 d
Details on results:
Oxygen consumption in the blank: 1.11 mg O2/L after 28 days of incubation
Key result
Parameter:
ThOD
Value:
2.71 mg O2/g test mat.
Results with reference substance:
14-day biodegradation of the positive control (sodium benzoate): 65.6%
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Under the study conditions, the test substance is considered not readily biodegradable.
Executive summary:

A study was conducted to determine the ready biodegradability of the test substance, 'di-C18-22 AAEMIM-MS' (active: 100%) using Close Bottle test, according to OECD Guideline 301D and EU Method 4.C-E, in compliance with GLP. Samples of secondary effluent were obtained as the test inoculum from a sewage plant treating predominantly domestic sewage. Aerobic conditions were maintained in the effluent. Sludge (0.6 mL/L) was exposed to 2 mg/L test substance for 28 d. An inoculum, a positive (sodium benzoate), and a toxicity control were included in the experiment. The concentration of dissolved oxygen in test and control bottles was determined on Days 5, 7, 11, 14, 18, 21, 25 and 28 and the results (in % biodegradation - O2 consumption) were reported as mg O2 consumed per mg test substance divided by ThOD * 100. The oxygen consumption in the blank was 1.11 mg O2/L after 28 d of incubation and the 14 d biodegradation of the positive control reached 65.6%. The test met all the validity criteria. On Day 28, the biodegradation of the test substance was 0%. Under the study conditions, the test substance is considered not readily biodegradable (Key Lab., 2010).

Description of key information

Based on the study results of the study, the test substance, 'di-C18-22 AAEMIM-MS', was 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

A study was conducted to determine the ready biodegradability of the test substance, 'di-C18-22 AAEMIM-MS' (active: 100%) using Close Bottle test, according to OECD Guideline 301D and EU Method 4.C-E, in compliance with GLP. Samples of secondary effluent were obtained as the test inoculum from a sewage plant treating predominantly domestic sewage. Aerobic conditions were maintained in the effluent. Sludge (0.6 mL/L) was exposed to 2 mg/L test substance for 28 d. An inoculum, a positive (sodium benzoate), and a toxicity control were included in the experiment. The concentration of dissolved oxygen in test and control bottles was determined on Days 5, 7, 11, 14, 18, 21, 25 and 28 and the results (in % biodegradation - O2 consumption) were reported as mg O2 consumed per mg test substance divided by ThOD * 100. The oxygen consumption in the blank was 1.11 mg O2/L after 28 d of incubation and the 14 d biodegradation of the positive control reached 65.6%. The test had met all the validity criteria. On Day 28, the biodegradation of the test substance was 0%. Under the study conditions, the test substance was considered not readily biodegradable (Key Lab., 2010).