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

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-01-19 to 2015-07-23

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Version / remarks:

2010

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on sampling:

- Concentrations: 10, 100, 1000 mg/L (nominal)
- Sampling method: After 3 hours, a standard BOD measuring bottle was filled from the contents, the respiration rate was measured for 10 minutes or until the dissolved oxygen level reached 2 mg/L.
- Sample storage conditions before analysis:

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test substance dissolved in deionised water to make a stock solution.
- Controls: Prepared the same way as test samples but without the test substance.
- Chemical name of vehicle (organic solvent, emulsifier or dispersant):NA
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)):
- Test concentration separation factor: NA
- Evidence of undissolved material (e.g. precipitate, surface film, etc.):NA

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture:No
- Name and location of sewage treatment plant where inoculum was collected: Chengdong, China (Batch No.: AS201503171)
- Method of cultivation: NS
- Preparation of inoculum for exposure:The sludge was washed three times with deionised water (it was centrifuged for 10 minutes, the supernatant decanted, then the remaining sludge solids resuspended in deionised water), then the wet solids were homogenised in a blender and suspended in deionised water. The sludge suspension was aerated overnight at 20±2 degrees Celsius at pH 7.34.
- Initial biomass concentration: 3 g/L

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

18-22 degrees Celsius

pH:

6.5 - 7.51

Dissolved oxygen:

NS

Salinity:

NS

Conductivity:

NS

Nominal and measured concentrations:

10, 100 and 1000 mg/L; the concentrations not measured.

Details on test conditions:

TEST SYSTEM
- Test vessel: 1 Litre beakers
- Material, size, headspace, fill volume: 1 Litre beakers, total volume of each reaction 500 ml
- Aeration: 0.8 litres per minute using a Pasteur pipette and an aeration device
- No. of vessels per concentration (replicates): 1 for 10 and 100 mg/L, 3 for 1000 mg/L
- No. of vessels per control (replicates):2
- No. of vessels per vehicle control (replicates): NA
- No. of vessels per abiotic control (replicates):1
- Sludge concentration (weight of dry solids per volume): 3 g/L
- Nutrients provided for bacteria: A synthetic sewage feed was provided (16 g peptone, 11 g meat extract, 3 g urea, 0.7 g NaCl, 0.4 g CaCl2 2H20, 0.2 g MgSO4 7H2O, 2.8 g K2HPO4. 16 mL of this was provided at the beginning of the experiment.
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: water was purified using Milli-Q (Millipore, USA) apparatus
- Particulate matter: Not measured
OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod:NS
- Light intensity:NS
- Details on termination of incubation:NA (respiration rate was measured directly in vessel)
EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
TEST CONCENTRATIONS
- Spacing factor for test concentrations:NA
- Justification for using fewer concentrations than requested by guideline:NA
- Range finding study: Yes
- Test concentrations: 10, 100, 1000 mg/L
- Results used to determine the conditions for the definitive study: No (The range finding study qualified as a limit test, measured EC50 was >1000 mg/L)

Reference substance (positive control):

yes

Remarks:

The microbial inoculums were exposed to 3,5-dichlorophenol at concentrations of 3, 10 and 30 mg/L

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other:

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No
- Adsorption (e.g. of test material to the walls of the test container): NS
- Blank controls oxygen uptake rate: 36.2 and 32.7 mg O2/L h
- Coefficient of variation of oxygen uptake rate in control replicates: Relative difference between the negative controls was 9.97% (within the 30% allowed by guidelines)

The results can be seen in Table in the "Any other information on results incl. tables" section. The EC50 for the test substance was established as >1000 mg/L.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: 3h EC50 of 3,5 dichlorophenol was calculated to be 4.60 mg/L (95% CR of 10.6 - 15 mg/L), which was within the range of 2-25 mg/L allowed by guidelines.

Table. Respiration Inhibition Range finding test
Beakers	Con. (mg/L)	O2 Concentration		Time (s)	Oxygen consumption rate mg O2/L h	% Inhibition
		Upper Value	Lower Value
1 Abiotic Control	1056	7.35	7.32	600	0.18	-
2. Neg. Control	0	6.50	2.00	448	36.2	-
3 Test	9.63	6.50	2.00	379	42.7	-24.1
4 Test	96.3	6.50	2.00	610	26.6	22.9
5 Test	1056	6.00	2.00	645	22.3	35.2
6 Test	1056	5.50	2.00	569	22.1	35.7
7 Test	1056	6.00	2.00	635	22.7	34.2
8 Pro. Control	3	6.50	2.00	512	31.6	8.15
9 Pro. Control	10	5.00	2.00	548	19.7	42.8
10 Pro. Control	30	5.90	4.70	600	7.20	79.1
11 Neg. Control	0	5.50	2.00	385	32.7	-
EC50 value of Test	>1000 mg/L		95% confidence limit		-
EC50 value of Reference	4.60 mg/L		95% confidence limit		3.70 ~ 5.72 mg/L

Validity criteria fulfilled:

yes

Remarks:

The oxygen uptake of the negative controls were 24.1 and 21.8 O2/g h (after considering the sludge concentration of 1.5 g/L) which fulfilled the validity criteria of no less than 20 mg O2/g h.

Conclusions:

The effects on the test item to the activated sludge respiration inhibition were investigated in a static test according to OECD 209 guidelines. Under the experimental conditions and based on nominal concentrations, the 3h-EC50 value was determined to be greater than 1000 mg/L. 

Executive summary:

This study was performed to assess the effects on the test item to the activated sludge respiration inhibition according to OECD Test Guideline 209 with GLP compliance. 

The respiration rate of an activated sludge fed with a standard amount of synthetic sewage feed was measured after a contact time of three hours. The respiration rate of the same activated sludge in the presence of 10, 100 and 1000 mg/L of test substance under otherwise identical conditions was also measured. The inhibitory effect of the test item at a particular concentration was expressed as a percentage difference from the mean respiration rates of the two controls. It was found that no significant inhibition of respiration was caused by the test substance. 

Under the experimental conditions and based on nominal concentrations, the 3h-EC50 value was determined to be >1000 mg/L. 

Description of key information

3 h NOEC = >1000 mg/L (Activated sludge respiration), OECD 209 (2010); Linjun, Z. (2015)

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

The key study was performed to assess the effects on the test item to the activated sludge respiration inhibition according to OECD Test Guideline 209 with GLP compliance. 

The respiration rate of an activated sludge fed with a standard amount of synthetic sewage feed was measured after a contact time of three hours. The respiration rate of the same activated sludge in the presence of 10, 100 and 1000 mg/L of test substance under otherwise identical conditions was also measured. The inhibitory effect of the test item at a particular concentration was expressed as a percentage difference from the mean respiration rates of the two controls. It was found that no significant inhibition of respiration was caused by the test substance. 

Under the experimental conditions and based on nominal concentrations, the 3h-EC50 value was determined to be >1000 mg/L.