1,1'-[[3-(dimethylamino)propyl]imino]bispropan-2-ol

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): 1,1-[[3-(dimethylamino)propyl]imino]bis(2-propanol)
- Physical state: liquid
- Analytical purity: 85.7%
- Impurities (identity and concentrations): not reported
- Lot/batch No.: PFW100241
- 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 1,1-[[3-(dimethylamino)propyl]imino]bis(2-propanol) was prepared in reverse osmosis water, the day before use.
- pH was measured as 10.9 and adjusted to 7.0 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: obtained from Totnes Sewage Works, Totnes, Devon, UK; predominantly domestic origin and 2 days prior to exposure
- Method of cultivation:
* left to settle and decanted
* settled sludge was fed with 50 mL of OECD synthetic sewage feed per liter of sludge per day
* sludge was aerated at room temperature
- Preparation of inoculum for exposure: 153 mL of activated sludge was mixed with 16 mL of synthetic sewage and corresponding test substance and water to obtain the nominal tested concentrations in a final volume of 500 mL
- Initial biomass concentration: total filterable solids concentration in the culture determined on the day of the test was 4886 mg/L at a pH of 7.0; suspended solids in test solutions was 1500 mg/L at the start of testing

SYNTHETIC SEWAGE
- synthetic sewage was prepared as described by the OECD guideline
- excess amount was added to the settled activated sludge

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

Not reported

Test temperature:

20 ± 2 °C

pH:

- control: at start 7.0-7.1 and at end 6.1-6.2
- 1,1-[[3-(dimethylamino)propyl]imino]bis(2-propanol): at start 6.9-7.1 and at end 5.9-6.3

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
- No. of vessels per concentration of reference substance (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reverse osmosis water
- Culture medium different from test medium: no
- Intervals of water quality measurement: pH and temperature (with mercury-in-glass thermometer) were measured at start and end, respiration rate was measured at end of exposure

OTHER TEST CONDITIONS
- Adjustment of pH: yes, prior to start of exposure (to 7.0)

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: no

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:

- EC20(3h) > 1000 mg/L
- EC80(3h) > 1000 mg/L
- Less then 10 % inhibition was observed in all test flasks.

Results with reference substance (positive control):

- EC50(3h) = 9.8 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 confirme the viability of the sludge organisms.

Reported statistics and error estimates:

none

Validity criteria fulfilled:

yes

Conclusions:

In this study, activated sludge from a predominantly domestic WWTP was exposed to 10, 100 and 1000 mg/L of test substance for 3 h, after which the oxygen consumption rate was measured. 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.

Description of key information

An activated sludge inhibition test (Harrigan and Daniel, 2011) was carried out according to the OECD guideline 209. No effects were observed up to and including the highest test concentration. The 3h-EC50 was >1000 mg/L and the 3h-NOEC was >= 1000 mg/L. 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