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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017-01-09 to 2017-01-26
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Version / remarks:
28th July 2011
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:
yes
Details on sampling:
- Concentrations: 0, 0.32, 1, 3.2, 10, 32, 100 mg/L
- Sampling method: Samples were taken at the beginning and at the end of the study
Vehicle:
yes
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: green algae
- Strain: No. 86.81
- Source (laboratory, culture collection): MBM Sciencebridge GmbH (Institut für Pflanzenphysiologie of Universität Göttingen)
- Method of cultivation: Four days before the start of each test, an aliquot of the permanent culture was brought into nutrient medium and incubated under continuous lighting for 96 hours. The resulting culture grew exponentially.

ACCLIMATION
- Culturing media and conditions: same as test
- Any deformed or abnormal cells observed: No
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
22.0 - 22.5 °C
pH:
7.8 - 8.1
Salinity:
Not applicable
Nominal and measured concentrations:
0.32, 1.0, 3.2, 10, 32, 100 mg/L (nominal)
0.4, 0.9, 3.4, 9.5, 29, 84.6 mg/L (geometric mean measured)
Details on test conditions:
TEST SYSTEM
- Test vessel: glass flasks, total volume 65 mL
- Type: closed
- Control end cells density: 4200/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per vehicle control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- preparation of dilution water: demineralised water enriched with minerals
- Culture medium different from test medium: No

OTHER TEST CONDITIONS
- Sterile test conditions: No
- Adjustment of pH: No
- Photoperiod: continuous lightening
- Light intensity and quality: 4500 Lux

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: electronic particle counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: ca. 3
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
43 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
3.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
3.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): Yes
- Observation of abnormalities (for algal test): No
- Unusual cell shape: No
- Colour differences: No
- Flocculation: No
- Adherence to test vessels: No
- Aggregation of algal cells: No
- Any stimulation of growth found in any treatment: No
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No
- Effect concentrations exceeding solubility of substance in test medium: No
Results with reference substance (positive control):
- Results with reference substance valid? Yes
The 72h-EC50s of potassium dichromate (K2Cr207, CAS No. 7778-50-9) were determined in a separate reference test. The values lay within the range of the laboratory (growth rate 0.73 - 1.10 mg/L, yield 0.21 - 0.66 mg/L).
Reported statistics and error estimates:
Calculation of results was performed with the help of validated software ((Microsoft Excel®). The estimation of the biological data was accomplished using the software ToxRat® Professional, version 3.2.1.
Validity criteria fulfilled:
yes
Conclusions:
In a 72-h growth inhibition test with green algae according to OECD guideline 201, an ErC50 of 43 mg/L and an ErC10 of 3.8 mg/L was determined.
Executive summary:

The effect of lithium amide on the growth of an algal species Desmodesmus subspicatus over a 72 hour static exposure period was assessed according to OECD guideline 201.

The study was performed using 5 concentrations ranging from 0.32 to 100 mg/L. Incubation time (test system Desmodesmus subspicatus) was 72 hours. The cell concentration of each replicate was determined by measuring the cell numbers every 24 hours with an electronic particle counter. Growth rate and the yield were determined from the cell number at the respective observation times.

In the 1st experiment two of the validity criteria were not met. Therefore, the experiment was repeated. The results of the first experiment are not stated in this report, but will be kept together with the other raw data in the GLP archive of the test facility. The 2nd experiment was performed likewise the 1st experiment.

In the 2nd experiment statistical significant inhibition of algal growth was observed at the following concentrations: 10, 32 and 100 mg/L (nominal concentration)

At the start and at the end of the 2nd experiment, the content of the test item in the test solutions was determined using NH4+-determination using a photometric method.

The measured concentrations laid between 78 % and 87 % of the nominal concentrations at the beginning of the test and between 85 % and 224 % of the nominal concentrations at the end of the test. Therefore, the determination of the results was based on the geometric mean of the measured concentrations.

The 72h-EC50 values of potassium dichromate (K2Cr2O7, CAS No. 7778-50-9) were determined in a separate reference test. The values laid within the range of the laboratory (growth rate 0.73 - 1.10 mg/L, yield 0.21 - 0.66 mg/L).

 

The following results for the test item lithium amide were determined:

 

Table 3-a Results of the test item

Endpoint

NOEC

LOEC

EC10

EC50

Growth Rate

3.4 mg/L

9.5 mg/L

3.8 mg/L

43 mg/L

Yield

3.4 mg/L

9.5 mg/L

2.0 mg/L

7.7 mg/L

 

Description of key information

In a 72-h growth inhibition test with green algae according to OECD guideline 201, an ErC50 of 43 mg/L and an ErC10 of 3.8 mg/L was determined with the source substance lithium amide.

Key value for chemical safety assessment

EC50 for freshwater algae:
43 mg/L
EC10 or NOEC for freshwater algae:
3.8 mg/L

Additional information

The effect of lithium amide on the growth of an algal species Desmodesmus subspicatus over a 72 hour static exposure period was assessed according to OECD guideline 201.

The study was performed using 5 concentrations ranging from 0.32 to 100 mg/L. Incubation time (test system Desmodesmus subspicatus) was 72 hours. The cell concentration of each replicate was determined by measuring the cell numbers every 24 hours with an electronic particle counter. Growth rate and the yield were determined from the cell number at the respective observation times.

In the 1st experiment two of the validity criteria were not met. Therefore, the experiment was repeated. The results of the first experiment are not stated in this report, but will be kept together with the other raw data in the GLP archive of the test facility. The 2nd experiment was performed likewise the 1st experiment.

In the 2nd experiment statistical significant inhibition of algal growth was observed at the following concentrations: 10, 32 and 100 mg/L (nominal concentration)

At the start and at the end of the 2nd experiment, the content of the test item in the test solutions was determined by NH4+-determination using a photometric method.

The measured concentrations laid between 78 % and 87 % of the nominal concentrations at the beginning of the test and between 85 % and 224 % of the nominal concentrations at the end of the test. Therefore, the determination of the results was based on the geometric mean of the measured concentrations.

The 72h-EC50 values of potassium dichromate (K2Cr2O7, CAS No. 7778-50-9) were determined in a separate reference test. The values laid within the range of the laboratory (growth rate 0.73 - 1.10 mg/L, yield 0.21 - 0.66 mg/L).

 

The following results for the test item lithium amide were determined:

 

Results of the test item

Endpoint

NOEC

LOEC

EC10

EC50

Growth Rate

3.4 mg/L

9.5 mg/L

3.8 mg/L

43 mg/L

Yield

3.4 mg/L

9.5 mg/L

2.0 mg/L

7.7 mg/L

 

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