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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
25.08.2008-22.09.2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report date:
2008

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Principles of method if other than guideline:
Deviating from the study plan additional inoculum blank assays had to be analysed due to variations in the 10 d-window between the two test item concentrations applied. These additional vessels were started originally as spare vessels.
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl]
EC Number:
930-947-3
IUPAC Name:
Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl]

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Fresh samples of activated sludge were withdrawn on August 25th, 2008 from the sewage treatment plant in Schmallenberg (Germany) which is mainly fed with municipal wastewater.
- Laboratory culture: no
- Preparation of inoculum for exposure: The samples were washed once with mineral medium after the arrival at the laboratory and kept aerobic until use.
- Pretreatment: no
- Concentration of sludge: 29.5 mg dry mass/L
- Water filtered: not reported (deionized water, free from inhibitory concentration of toxic substances)
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
25 mg/L
Based on:
test mat.
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral medium according to guideline
- Additional substrate: no
- Solubilising agent (type and concentration if used): no
- Test temperature: 22°C
- pH: Initial pH adjusted to 7.4 ± 0.2; at the end of the test the pH values of all solutions were determined. They were in the range between 7.5 and 7.7 in all test vessels.
- pH adjusted: yes
- Aeration of dilution water: not reported
- Suspended solids concentration: 29.5 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Sapromat
- Number of culture flasks/concentration: 5 until the end of the 10 d-window, thereafter 2
- Method used to create aerobic conditions: The activated sludge was kept in aerobic condition until use. The test vessels were aerated during the whole test.
- Measuring equipment: Sapromat respirometer (VOITH Inc.)
- Test performed in closed vessels: yes
- Details of trap for CO2 and volatile organics if used: Evolved carbon dioxide was absorbed in a suitable absorbent (not further specified)

SAMPLING
- Sampling frequency: daily
- Sample storage before analysis: no

CONTROL AND BLANK SYSTEM
- Inoculum blank: performed
- Abiotic sterile control: performed
- Toxicity control: performed
- Other: functional/procedural control (reference substance) performed
Reference substance
Reference substance:
benzoic acid, sodium salt
Remarks:
(100 mg/L)

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
ca. 23
Sampling time:
2 d
Remarks on result:
other: 25 mg/L test item
Parameter:
% degradation (O2 consumption)
Value:
ca. 67
Sampling time:
12 d
Remarks on result:
other: 25 mg/L test item
Parameter:
% degradation (O2 consumption)
Value:
81
Sampling time:
28 d
Remarks on result:
other: 25 mg/L test item
Parameter:
% degradation (O2 consumption)
Value:
ca. 14
Sampling time:
4 d
Remarks on result:
other: 100 mg/L test item
Parameter:
% degradation (O2 consumption)
Value:
57
Sampling time:
28 d
Remarks on result:
other: 100 mg/L test item

BOD5 / COD results

Results with reference substance:
The reference item sodium benzoate was biodegraded by 90 % after 14 days and thus fulfilling the guideline requirements.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl] proved to be readily biodegradable (81 % biodegradation after 28 d) in a study conducted according to OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test) and EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test).
Executive summary:

The ready biodegradation of Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl] was investigated in a study conducted according to OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test) and EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test) over a period of 28 days and using domestic activated sludge as inoculum. The biodegradation rate was determined by measurement of oxygen consumption. Inoculum blank, abiotic control, procedural/functional control with the reference substance sodium benzoate, and toxicity control using 100 mg/L test item and 100 mg/L reference compound were performed.

The test item proved to be readily biodegradable at a test substance concentration of 25 mg/L (81 % biodegradation after 28 d). At a concentration of 100 mg/L, the test substance was biodegraded by 57 % after 28 d; thus, the pass level of 60% biodegradation was not reached. However, due to the high ThOD of 2.73 mg O2/mg test substance, the test item suspension with a concentration of 25 mg/L met the criteria of 50 -100 mg ThOD or COD/L as demanded in the guideline.

No significant nitrification was observed until test end (at most 7.6 % of theoretical NO3 production in the higher concentrated assay). No abiotic degradation of the test item was observed.

The reference item sodium benzoate was biodegraded by 90 % after 14 days and thus fulfilling the guideline requirements.

In the toxicity control (100 mg/L test and reference substance each) the biodegradation amounted to 62 % after 14 d. Thus, the test item can be considered as non toxic to the inoculum. The oxygen uptake of the inoculum blank was < 60 mg/L in 28 d and the pH was inside the range of 6.0 -8.5. The difference of extremes of replicate values of the removal of the test item at the end of the test was less than 20 %.

The test item was readily biodegradable and fulfilled the 10-d window criterion. This study is regarded as reliable without restriction and satisfies the guideline requirements for ready biodegradation.