Lithium amide

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:

2016-12-14 to 2017-04-11

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:

adopted 22nd July 2010

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Version / remarks:

adopted 7th Dec. 2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Expiration date of the batch: 2017-03-11

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room Temperature (20 ± 5 °C); Keep under inert gas

OTHER SPECIFICS: fine powder, white to grey

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method:
A stock solution of the test item containing 10001 mg/L (first experiment) respectively 10015 mg/L (second experiment) was prepared. This was done by weighing the nominal load into a volumetric flask. The test item was solved in demineralised water and the pH of this solution was adjusted to pH 7 - 8 with HCl 36.5 % (controlled with indicator paper). Then the volumetric flask was filled up with demineralised water. This solution was used for preparation of the treatments.

- Controls:
3,5-Dichlorophenol (CAS-No. 591-35-5) was used as positive control.
For blank control, 16 mL nutrient solution was mixed with 234 mL water.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant in 67435 NW-Lachen-Speyerdorf, Germany.
- Method of cultivation: Upon arrival in the test facility, the sludge was filtrated, washed with tap water 3 times and re-suspended in tap water. The activated sludge was aerated until usage in the test and fed daily with 50 mL synthetic sewage feed /L.
- Preparation of inoculum for exposure: On the day before the experiment, the inoculum was taken from its source, washed, aerated and the dry matter was determined. Volume was adapted to the desired content of dry matter. On the day of the experiment, the dry matter was determined once more.
- Pretreatment: The nutrient solution was thawed and the sludge was fed with 50 mL nutrient solution / L sludge.
- Initial biomass concentration: Dry matter in the test: 1.55 - 158 g suspended solids/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

0.83 mmol/L

Test temperature:

21.4 - 22.6 °C

pH:

8.16

Conductivity:

228 µS/cm

Nominal and measured concentrations:

Nominal: 1000, 100, 10, 1 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: SCHOTT-flasks
- Type: closed
- Material, fill volume: glass, 2000 mL
- Aeration: No
- No. of vessels per concentration (replicates): 1 per concentration (100, 10, 1 mg/L), 5 per concentration (1000 mg/L)
- No. of vessels per blank control (replicates): 2
- No. of vessels per positive control (replicates): 1
- Sludge concentration (weight of dry solids per volume): 1.55 g suspended solids/L
- Nutrients provided for bacteria: Peptone 16.0 g, Meat Extract 11.0 g, Urea 3.0 g, NaCl 0.7 g, CaCl2*2H2O 0.4 g, MgSO4*7H2O 0.2 g, K2HPO 42.8 g

TEST MEDIUM / WATER PARAMETERS
- Source of dilution water: tap water

OTHER TEST CONDITIONS
- Adjustment of pH: No,

EFFECT PARAMETERS MEASURED
TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Test concentrations: 1000, 100, 10,1 mg/L

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (CAS-No. 591-35-5) was used as positive control. A stock solution in deionised water containing 500 mg/L was freshly prepared for the experiment. Concentrations of 5.0, 10.0, 20.0, and 40.0 mg/L were used.

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

440 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

160 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: EC50 = 8.4 mg/L

Validity criteria fulfilled:

yes

Conclusions:

In an Activated Sludge Respiration Inhibition Test according to OECD Guideline 209, an EC50 of 440 mg/L was determined (EC10 = 160 mg/L).

Executive summary:

The influence of the test item lithium amide on the activity of activated sludge by measuring the respiration rate was evaluated according to OECD Guideline 209 and EU method C.11. The respiration rate (oxygen consumption) of an aerobic activated sludge fed with a standard amount of synthetic sewage was measured in the presence of various concentrations of the test item after an incubation period of 3 hours. The inhibitory effect of the test item at the particular concentrations was expressed as percentage of the mean respiration rate of two controls. Following test concentrations were used: 1.0, 10, 100, and 1000 mg/L; 5.0, 10.0, 20.0, and 40.0 mg/L 3,5-Dichlorophenol/L and two blank controls. In comparison to the inoculum controls the respiration rate of the activated sludge was inhibited between –8.7 % and 85.2 % up to the highest nominal test concentration of 1000 mg/L. Concentrations exceeding 1000 mg/L nominal were not tested. The 3-hour EC 50 for the positive control 3,5-Dichlorophenol, which was tested in the same way as the test item, was found to be 6.2 mg/L and is within the range of 2 – 25 mg/L recommended by the test guidelines; thus, confirming suitability of the activated sludge.
The 3 hours EC10 and EC50 values for the test substance lithium amide in the Activated Sludge Respiration Inhibition Test were 160 and 440 mg/L (based on measured inhibition rates), respectively.

Description of key information

In an Activated Sludge Respiration Inhibition Test according to OECD Guideline 209, an EC50 of 440 mg/L was determined (EC10 = 160 mg/L).

Key value for chemical safety assessment

EC50 for microorganisms:

440 mg/L

EC10 or NOEC for microorganisms:

160 mg/L

Additional information

The influence of the test item lithium amide on the activity of activated sludge by measuring the respiration rate was evaluated according to OECD Guideline 209 and EU method C.11. The respiration rate (oxygen consumption) of an aerobic activated sludge fed with a standard amount of synthetic sewage was measured in the presence of various concentrations of the test item after an incubation period of 3 hours. The inhibitory effect of the test item at the particular concentrations was expressed as percentage of the mean respiration rate of two controls. Following test concentrations were used: 1.0, 10, 100, and 1000 mg/L; 5.0, 10.0, 20.0, and 40.0 mg/L 3,5-Dichlorophenol/L and two blank controls. In comparison to the inoculum controls the respiration rate of the activated sludge was inhibited between –8.7 % and 85.2 % up to the highest nominal test concentration of 1000 mg/L. Concentrations exceeding 1000 mg/L nominal were not tested. The 3-hour EC 50 for the positive control 3,5-Dichlorophenol, which was tested in the same way as the test item, was found to be 6.2 mg/L and is within the range of 2 – 25 mg/L recommended by the test guidelines; thus, confirming suitability of the activated sludge.
The 3 hours EC10 and EC50 values for the test substance lithium amide in the Activated Sludge Respiration Inhibition Test were 160 and 440 mg/L (based on measured inhibition rates), respectively.