N,N-bis(2-hydroxyethyl)-3-[(C16-18)alkoxy]-1-propanamine

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:

26 February 2018 - 27 February 2018

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))

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch: E00268-015-141
Purity: 100%
Physical state/Appearance: amber colored gelatinous solid

Analytical monitoring:

not specified

Details on sampling:

- Concentrations: 10, 100 and 1000 mg/L (three replicates at 1000 mg/L).
- Sampling method: Rate of respiration measured after 3 hours contact time

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION:
5, 50 and 500 mg (500 mg in triplicate) each separately dispersed in approximately 200 mL of deionized reverse osmosis water and subjected to ultrasonication for approximately 15 minutes followed by magnetic stirring for 24 hours, at room temperature, in order to maximize the dissolved test item concentration.
All test vessels were shielded from the light during mixing.
Synthetic sewage (16 mL), activated sewage sludge (250 mL) and water were added to a final volume of 500 mL to give the required concentrations of 10, 100 and 1000 mg/L (three replicates at 1000 mg/L).

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture: not specified
- Name and location of sewage treatment plant where inoculum was collected: Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK
- Method of cultivation: A mixed population of activated sewage sludge micro-organisms was obtained. On the day of collection the activated sewage sludge (9.5 liters) was fed synthetic sewage (475 mL).
- Preparation of inoculum for exposure: maintained on continuous aeration at approximately 21 ºC overnight prior to use in the test.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Remarks on exposure duration:

The test was conducted under normal laboratory lighting in a temperature controlled room at a measured temperature of approximately 20 °C.

Post exposure observation period:

not applicable

Hardness:

not specified

Test temperature:

20 °C

pH:

7.8 - 7.9

Dissolved oxygen:

See table 1

Salinity:

not specified

Conductivity:

not specified

Nominal and measured concentrations:

Nominal concentrations: 10, 100, 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 mL conical flasks
- Type (delete if not applicable): closed
- Aeration: Clean, oil-free compressed air via narrow bore glass tubes at a rate of 0.5 to 1.0 liter per minute
- No. of vessels per concentration (replicates): one, except 1000mg/L where there were 3 replicates
- No. of vessels per control (replicates): 4
- Sludge concentration (weight of dry solids per volume): 3.0 g/L prior to use.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Deionized reverse osmosis water containing less than 1 mg/L Total Organic Carbon (TOC).
- Particulate matter: not specified

OTHER TEST CONDITIONS
- Adjustment of pH: Adjusted to between pH 7.0 and 8.0 if necessary
- Photoperiod: not specified
- Light intensity: normal laboratory lighting
- Details on termination of incubation: After 3 hours contact time an aliquot was removed from the conical flask and poured into the measuring vessel (250 mL darkened glass Biological Oxygen Demand (BOD) bottle) and the rate of respiration measured using a Yellow Springs dissolved oxygen meter fitted with a BOD probe. The contents of the measuring vessel were stirred constantly by magnetic stirrer. The rate of respiration for each flask was measured over the linear portion of the oxygen consumption trace (where possible between 7 mg O2/L and 2 mg O2/L).

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): The pH was measured at the test start (i.e. after the addition of activated sludge) and at the end of the 3-Hour incubation period. The oxygen concentrations in all vessels were measured after 30 minutes contact time. Rate of respiration measured after 3 hours incubation.

TEST CONCENTRATIONS
- Range finding study : 10, 100 and 1000 mg/L

Reference substance (positive control):

yes

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

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

ca. 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: not specified
- Effect concentrations exceeding solubility of substance in test medium: not specified
- Adsorption (e.g. of test material to the walls of the test container): not specified
- Blank controls oxygen uptake rate: 39 - 42 mg O2/L/hour
- Coefficient of variation of oxygen uptake rate in control replicates: 3.2%
Full results shown in table 2.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: The EC50 value (3-Hour contact time) for the reference item, 3,5-Dichlorophenol, was 7.6 mg/L.

Reported statistics and error estimates:

Not specified

Table 2.

Inhibition of respiration rate.

	EXP1505486		3,5-Dichlorophenol
	ECx(3 Hours) (mg/L)	95% Confidence Limits (mg/L)	ECx(3 Hours) (mg/L)	95% Confidence Limits (mg/L)
EC10	>1000	-	1.7	-
EC20	>1000	-	2.5	-
EC50	>1000	-	7.6	5.9 – 9.8
EC80	>1000	-	24	-
NOEC	1000	-	-	-

Validity criteria fulfilled:

yes

Conclusions:

The effect of the test item on the respiration of activated sewage sludge micro-organisms gave a 3-Hour EC50 value of greater than 1000 mg/L. The NOEC after 3 hours exposure was 1000 mg/L.

Description of key information

The effect of the test item on the respiration of activated sewage sludge micro-organisms gave a 3-Hour EC50 value of greater than 1000 mg/L. The NOEC after 3 hours exposure was 1000 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

1 000 mg/L