N'-[3-(dimethylamino)propyl]-N,N-dimethylpropane-1,3-diamine

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:

2011-08-16 - 2011-08-18

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

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

- Name of test material (as cited in study report): Bis-DMAPA
- Physical state: liquid
- Analytical purity: 97.8%
- Impurities (identity and concentrations): not reported
- Lot/batch No.: PFW110019
- Supplier: SGS Belgium N.V.
- Stability under test conditions: not reported
- Storage condition of test material: at ambient temperature

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

- Nominal stock solution of 5000 mg/L test substance was prepared in reverse osmosis water, the day before use.
- Stock solution was clear colourless.
- pH of stock solution was measured as 10.3 and adjusted to 8.0 with HCl.
- Test solutions were prepared by adding known volumes of stock solution to a total volume of 500 mL RO water, synthetic sewage and activated sludge.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

ACTIVATED SLUDGE
- Laboratory culture: no
- Source: Totnes Sewage Works, Totnes, Devon, UK (predominantly domestic origin). Sludge collected 2 days prior to testing.
- Method of cultivation:
* left to settle and supernatant decanted
* settled sludge was fed with 50 mL of OECD synthetic sewage (prepared as described by the OECD guideline) per liter of sludge per day
* sludge was aerated at room temperature
* total filterable solids on the day of the test was 4886 mg/L and pH was 7.0
- Initial suspended solids concentration in the test was 1500 mg/L.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

yes, for measurement of oxygen uptake rate

Hardness:

Not reported.

Test temperature:

20 ± 2 °C

pH:

- Control: at start 7.0-7.1 and at end 6.1-6.2
- Bis-DMAPA: at start 7.1-7.8 and at end 6.1-7.4

Dissolved oxygen:

Not applicable.

Salinity:

Not applicable.

Nominal and measured concentrations:

Nominal concentrations: blank, 10, 100 and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: culture flask
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: fill volume of 500 mL, no other details reported
- Aeration: yes
- No. of vessels per concentration (replicates): 3 for 1000 mg/L and 1 for 10 and 100 mg/L
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reverse osmosis water
- Culture medium different from test medium: no
- Test medium consisted of an excess of synthetic sewage (prepared according to the guideline and using reverse osmosis water as dilution water), sufficient activated sludge (1500 mg SS/L), and an appropriate amount of stock solution of the test substance to reach the test concentration under consideration.

OTHER TEST CONDITIONS
- Adjustment of pH: yes, prior to start of exposure
- Photoperiod: not applicable

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): respiration rate, measured after 3 hours in glass samples tubes into which microcathode oxygen electrodes were inserted, and expressed as mg/L/h

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Range finding study: yes, only the range finding study was performed

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

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:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

Less then 10 % inhibition was observed in all test flasks.

Results with reference substance (positive control):

- 3-h EC50 = 10 mg/L, which is within the normal range of 2 to 25 mg/L.
- The results with the reference substance indicate that the sludge in this test is responding normally and confirm the viability of the sludge organisms.

Reported statistics and error estimates:

No statistics used (because no effects were observed).

Validity criteria fulfilled:

yes

Conclusions:

In this study, activated sludge from a predominantly domestic WWTP was exposed to 10, 100 and 1000 mg/L test substance for 3 h, after which the oxygen consumption rate was measured in closed BOD bottles. No significant differences in oxygen consumption rate were observed compared to the control. Therefore, the EC50 and NOEC were concluded to be > 1000 mg/L and >= 1000 mg/L, respectively. The results of this study can be considered reliable.

Description of key information

An activated sludge inhibitation test (Harrigan and Daniel, 2011) carried out according to the OECD guideline 209 resulted in a 3h-EC50 of >1000 mg/L and a 3h-NOEC of >=1000 mg/L (based on nominal concentrations). The study is given a Klimisch score of 1, was conducted under GLP and is considered as the key study for endpoint coverage.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L