N-[3-(dimethylamino)propyl]stearamide monoacetate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2014-11-10 to 2015-03-23

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Nanjing Chengdong Sewage Treatment Plant, Batch No.: AS20141202.
- Laboratory culture: No
- Storage conditions: NS
- Storage length: NS
- Preparation of inoculum for exposure: The sludge was washed three times by Basal Salts Medium and centrifugation
- Concentration of sludge: Mixed Liquor suspended solids levels of 4g
- Water filtered: yes
- Type and size of filter used, if any:Water Purification System (mili-Q, Millipore,USA)

Duration of test (contact time):

28 d

Initial conc.:

29.9 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: The Basal salts Medium used for the experiment was prepared by mixing 10 mL of solution A with 800 mL deionised water, followed by addition of 1 mL of solutions B, C and D, then the appropriate amount of deionised water was added to make up 1 L. Solutions A, B and C are as follows:

Stock solution A:
KH2PO4 (potassium dihydrogen phosphate): 8.5 g/L
K2HPO4 (dipotassium hydrogen phosphate): 21.75 g/L
Na2HPO4.2H2O (disodium monohydrogen phosphate dehydrate): 33.4 g/L
NH4Cl (Ammonium chloride): 0.5 g/L
Dissolved and made up to 1 L with deionised water
pH: 7.42

Stock solution B
CaCl2 (Calcium chloride): 27.5 g/L
Dissolved and made up to 1 L with deionised water

Stock solution C
MgSO4.7H2O (Magnesium sulphate heptahydrate): 22.5 g/L
Dissolved and made up to 1 L with deionised water

Stock solution D
FeCl3.6H2O (Iron(III)chloride hexahydrate): 0.25 g/L
Dissolved and made up to 1 L with deionised water
Added one drop of concentrated hydrochloric acid.

- Additional substrate: NA
- Test temperature: 21.5 - 22.1 degrees Celsius
- pH: 7.31 - 7.68
- pH adjusted: NS
- CEC (meq/100 g):
- Aeration of dilution water: NS
- Suspended solids concentration: 30 g/L (in vessel)
- Continuous darkness: yes
- Other:

TEST SYSTEM
- Culturing apparatus: Flasks (BOD bottle vessel flasks, total volume: 500 mL, volume of contents: 300 mL each) with Teflon magnetic stirrers. Air pump (AC0 -318, Guangdong Haley Group Co., Ltd.)
- Number of culture flasks/concentration: 2 test flasks (test substance 29.9 mg/L starting concentration, 30 mg/L inoculum), 2 inoculum (30 mg/L) controls, 1 procedural control (with reference substance (50 mg/L) and inoculum (30 mg/L)), 1 inhibition control (test substance (29.9 mg/L, reference substance (50 mg/L) and inoculum (30 mg/L)).
- Method used to create aerobic conditions: NA
- Method used to create anaerobic conditions: NS
- Measuring equipment: BOD meter (OxiTop Control 6, WTW, Germany)

SAMPLING
- Sampling frequency: daily
- Sampling method: Oxygen uptake measured from the apparatus

Reference substance:

benzoic acid, sodium salt

Remarks:

test concentration 50 mg/L, Lot No.: 20130117, purity ≥99.5%

Test performance:

Test ran according to plan

Key result

Parameter:

% degradation (O2 consumption)

Value:

97

Sampling time:

28 d

Details on results:

The test temperature remained between 21.5 and 22.1 degrees Celsius, measured pH remained between 7.31 and 7.68. Total oxygen uptake by the inoculum blank was 29 mg O2/L at the end of the test (therefore fulfilled the validity criteria of not exceeding 60 mg O2/L). The differences between replicate values for inoculum blank and test were less than 20%. Biodegradation of inhibition control was 80% at 14 days (above the minimum of 25%), therefore there was no inhibition effect to the inoculum.
The results showed that under the specific experimental conditions, biodegradation of the test substance calculated based on ThOD (NO3) was 97% after 28 days and 75.7% during at the 10 day window measurements. (See Biodegradation curve figure in the "Overall remarks, attachments" section) According to they experiment the test substance can therefore be classed as readily biodegradable.

Results with reference substance:

The biodegradation percentage of the reference substance, sodium benzoate, was 68.3% at day 14, confirming the suitability of the inoculum used (above the minimum of 25% stated by guideline).

Validity criteria fulfilled:

yes

Remarks:

See details in the "Results and Discussion" section

Interpretation of results:

readily biodegradable

Conclusions:

The results showed that under the specific experimental conditions, biodegradation of the test substance calculated based on ThOD (NO3) was 97%. As the 10-day window was achieved, the substance is considered readily biodegradable.

Executive summary:

The study was performed to assess the biotic degradation of the test substance by performing a ready biodegradability test, according to OECD Test Guideline 301F and EU Method C.4, with GLP compliance. 

Test vessels were filled with the test substance at a nominal concentration of 29.9 mg/L and inoculated with activated sludge at a concentration of suspended solids of  30 mg/L. In the meantime, a series of blanks were filled with inoculated mineral medium.  Test vessels containing the reference substance sodium benzoate ( 50 mg/L) were tested in order to check the procedure. A toxicity control, containing both the test substance and the reference substance, was also performed in order to check the absence of test substance toxic effect on the microbial inoculum. The oxygen uptake in test vessels from each group incubated at temperatures between 21.5°C  and 22.1°C in darkness was continuously recorded until the end of the test.

All validity criteria were fulfilled. The reference substance, sodium benzoate, was biodegraded by 68.3 % after 14 days and the toxicity control showed that the test substance had no inhibitory effect on the activity of the microbial inoculum. 

In conclusion, the results showed that under the specific experimental conditions, biodegradation of the test substance calculated based on ThOD (NO3) was 97% after 28 days.  As the 10-day window was achieved, the test substance can be considered as readily biodegradable under the experimental conditions.

Description of key information

Ready biodegradable; OECD 301F; Linjun, Z. (2015)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The key study was performed to assess the biotic degradation of the test substance by performing a ready biodegradability test, according to OECD Test Guideline 301F and EU Method C.4, with GLP compliance. 

Test vessels were filled with the test substance at a nominal concentration of 29.9 mg/L and inoculated with activated sludge at a concentration of suspended solids of  30 mg/L. In the meantime, a series of blanks were filled with inoculated mineral medium.  Test vessels containing the reference substance sodium benzoate ( 50 mg/L) were tested in order to check the procedure. A toxicity control, containing both the test substance and the reference substance, was also performed in order to check the absence of test substance toxic effect on the microbial inoculum. The oxygen uptake in test vessels from each group incubated at temperatures between 21.5°C  and 22.1°C in darkness was continuously recorded until the end of the test.

All validity criteria were fulfilled. The reference substance, sodium benzoate, was biodegraded by 68.3 % after 14 days and the toxicity control showed that the test substance had no inhibitory effect on the activity of the microbial inoculum. 

In conclusion, the results showed that under the specific experimental conditions, biodegradation of the test substance calculated based on ThOD (NO3) was 97% after 28 days. As the 10-day window was achieved, the test substance can be considered as readily biodegradable under the experimental conditions.