N-(2-hydroxyethyl)stearamide

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:

From May 20, 2005 to June 17, 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

yes

Remarks:

; there was slight higher oxygen depletion in the inoculum control; however it has no impact on the quality and integrity of the study.

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Municipal sewage treatment plant, D-31137 Hildesheim
- Pretreatment: The activated sludge was filtered with folded filter. The first 200 mL of the filtrate was not used. The second filtrate effluent from the domestic waste water was used to initiate inoculation.
-Colony forming units in the test vessels: 104-106 CFU/L

Duration of test (contact time):

ca. 28 d

Initial conc.:

3.33 mg/L

Based on:

other: test concentration (i.e., equivalent to COD of 10.22 mgO2/L; ThOD of 9.03 mgO2/L )

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral nutrient solution according to to OECD 301D
- Test temperature: 20-24 (constant ± 1°C)
- pH: 7.52
- Continuous darkness: yes, in an incubator
- Dispersion treatment: Agitation

TEST SYSTEM:
- Culturing apparatus: 300 mL BOD bottles with glass stoppers
- Number of culture flasks/concentration: Duplicates
- Method used to create aerobic conditions: Aerated until oxygen saturation

SAMPLING:
- Oxygen consumption was measured on Day 0, 7, 14, 21 and 28.

CONTROL AND BLANK SYSTEM
Inoculum control: Nutrient solution and inoculum
Toxicity control: 100 mL of test substance (1.67 mg/L) + 5 mg/L reference substance + nutrient solution and inoculum

PERFORMACE OF THE TEST: Based on the chemical oxygen demand (COD) the test concentration of 3.33 mg/L corresponding to oxygen demand of 10.22 mg O2 in the vessel was selected. Inoculum (0.2 mL) and test substance in a mineral culture medium were placed in closed flasks and kept at a constant temperature of 20-24 (constant +/- 1°C) in the dark in an incubator. Oxygen consumption of the inoculums control, functional control, test substance and toxicity control was determined.

Reference substance:

acetic acid, sodium salt

Remarks:

at 10 mg/L (ThOD = 0.78 mg O2/mg)

Key result

Parameter:

% degradation (O2 consumption)

Value:

ca. 69

Sampling time:

28 d

Details on results:

- Inoculum control: The oxygen demand in the inoculum control came to 2.11 mgO2/L after 28 d.
- Toxicity control: The biodegradation rate came to 51% after 14 d and reached 65% after 28 d.

Results with reference substance:

For the reference substance, the pass level of >60% was reached after 11 days. After 28 days, the biodegradation reached 74%.

None.

Validity criteria fulfilled:

yes

Remarks:

There was slight higher oxygen depletion (>1.5 mg O2/L) in the inoculum control; however it had no impact on the quality and integrity of the study.

Interpretation of results:

readily biodegradable

Conclusions:

Under the study conditions, the test substance was considered to be readily biodegradable.

Executive summary:

A study was performed to assess the ready biodegradability of the test substance, C16-18 MEA, in non-adapted municipal activated sludge according to OECD Guideline 301D (Closed bottle test), in compliance with GLP. The test substance concentration was 3.33 mg/L, corresponding to 10.22 mg O2/L in the test vessel. Degradation was analysed by measuring the oxygen concentrations over a period of 28 d. The biodegradation was expressed as the percentage BOD and calculated for each oxygen analysis. Sodium acetate was used as the reference control at 10 mg/L. The test substance reached the 10% level (beginning of degradation) after 2 d. The pass level of >60% was reached after 17 d. The degradation reached a maximum of 69% after 28 d. The biodegradation for the reference substance reached 68% after 14 d. All the validity criteria according to the guideline were fulfilled. Under the study conditions, the test substance was considered readily biodegradable (Fiebig, 2005).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

A study was performed to assess the ready biodegradability of the test substance, C16-18 MEA, in non-adapted municipal activated sludge according to OECD Guideline 301D (Closed bottle test), in compliance with GLP. The test substance concentration was 3.33 mg/L, corresponding to 10.22 mg O2/L in the test vessel. Degradation was analysed by measuring the oxygen concentrations over a period of 28 d. The biodegradation was expressed as the percentage BOD and calculated for each oxygen analysis. Sodium acetate was used as the reference control at 10 mg/L. The test substance reached the 10% level (beginning of degradation) after 2 d. The pass level of >60% was reached after 17 d. The degradation reached a maximum of 69% after 28 d. The biodegradation for the reference substance reached 68% after 14 d. All the validity criteria according to the guideline were fulfilled. Under the study conditions, the test substance was considered readily biodegradable (Fiebig, 2005).