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EC number: 204-599-1 | CAS number: 123-08-0
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Toxicity to aquatic algae and cyanobacteria
Administrative data
Link to relevant study record(s)
- Endpoint:
- toxicity to aquatic algae and cyanobacteria
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2017-10-05 to 2018-01-31
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 201 (Alga, Growth Inhibition Test)
- Version / remarks:
- adopted on March 23, 2006; Annex 5 corrected: July 28, 2011
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- EU Method C.3 (Algal Inhibition test)
- Version / remarks:
- Commission Regulation (EU) 2016/266 of 7 December 2015 amending, for the purpose of its adaptation to technical progress, Regulation (EC) No 440/2008 laying down test methods pursuant to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH)
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Analytical monitoring:
- yes
- Details on sampling:
- Concentrations:
1.0, 3.2, 10.0, 31.6 and 100.0 mg/L
Sampling method:
Two replicates of each sample were deep-frozen (< -20 °C) directly after preparation and after 24h, 48h and 72h and stored in a freezer until analysis. Before freezing the samples after 24h, 48h and 72h exposure, the algae were separated from the medium by centrifugation at a low g-force (4000g for 20 minutes), sufficient to settle the algae. Additionally, analysis of all test item concentrations not inoculated with algae were performed. Analysis of the test item concentration at the beginning and at the end of each exposure period were performed in an analytical laboratory at the test facility using a HPLC method with UV-detection. - Vehicle:
- yes
- Remarks:
- Reconstituted water
- Details on test solutions:
- PREPARATION OF THE TEST MATERIAL
A preparation with a test item concentration of 100 mg/L was freshly prepared. For that purpose, the test item was weighed in a calibrated flask and vehicle was added. The preparation was stirred with a magnetic stirrer for 1 hour. This solution was used for the preparation of the different test item concentrations. The pH value was not adjusted. - Test organisms (species):
- Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
- Details on test organisms:
- TEST ORGANISM
- Common name: Unicellular green alga
- Strain: 61.81 SAG
- Source: „Pflanzenphysiologisches Institut der Universität Göttingen", Germany.
- Method of cultivation: For cultivation, 300 mL Erlenmeyer flasks filled with 100 mL algae suspension were covered with air permeable stoppers. The cultures were shaken continuously at about 120 rpm and lit between 4440 and 8880 Lux.
ACCLIMATION
- Acclimation period: 3 days
- 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
- Hardness:
- 24 mg/L as CaCO3 (calculated)
- Test temperature:
- 23.1 - 24.7 °C
- pH:
- 7.03 - 8.33
- Nominal and measured concentrations:
- Nominal concentrations: 1.0, 3.2, 10.0, 31.6 and 100.0 mg/L
Measured concentrations: >80 % of nominal concentrations - Details on test conditions:
- TEST SYSTEM
- Test vessel: 300 mL Erlenmeyer flasks
- Type: open
- Material, size, fill volume: glass, 300 mL filled with 100 mL cell suspension
- Aeration: no
- Initial cells density: 10 000 cells per mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
GROWTH MEDIUM
- Standard medium used: yes
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted water according to OECD TG 201
- Culture medium different from test medium: no
OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Light intensity and quality: The mean light intensities were 7510 Lux ± 3.4 % and 7585 Lux ± 3.7 % prior to and at the end of the exposure period, respectively.
The mean light intensities for the samples used for analytical determination after 24 and 48 hours were 7604 Lux ± 2.7 % and 7869 Lux ± 2.9 % prior to and at the end of the exposure period, respectively.
EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: electronic particle counter
TEST CONCENTRATIONS
- Spacing factor for test concentrations: appr. 3.16
- Test concentrations: 1.0, 3.2, 10.0, 31.6 and 100.0 mg/L - Reference substance (positive control):
- yes
- Remarks:
- Potassium dichromate
- Key result
- Duration:
- 72 h
- Dose descriptor:
- EC10
- Effect conc.:
- 7.12 mg/L
- Nominal / measured:
- meas. (initial)
- Conc. based on:
- test mat.
- Basis for effect:
- growth rate
- Remarks on result:
- other: EC10 based on nominal concentrations
- Duration:
- 72 h
- Dose descriptor:
- EC20
- Effect conc.:
- 12.64 mg/L
- Nominal / measured:
- meas. (initial)
- Conc. based on:
- test mat.
- Basis for effect:
- growth rate
- Remarks on result:
- other: EC20 based on nominal concentrations
- Key result
- Duration:
- 72 h
- Dose descriptor:
- EC50
- Effect conc.:
- 37.93 mg/L
- Nominal / measured:
- meas. (initial)
- Conc. based on:
- test mat.
- Basis for effect:
- growth rate
- Remarks on result:
- other: EC50 based on nominal concentrations
- Duration:
- 72 h
- Dose descriptor:
- EC10
- Effect conc.:
- 3.29 mg/L
- Nominal / measured:
- meas. (initial)
- Conc. based on:
- test mat.
- Basis for effect:
- other: Yield
- Remarks on result:
- other: EC10 based on nominal concentrations
- Duration:
- 72 h
- Dose descriptor:
- EC20
- Effect conc.:
- 4.85 mg/L
- Nominal / measured:
- meas. (initial)
- Conc. based on:
- test mat.
- Basis for effect:
- other: Yield
- Remarks on result:
- other: EC20 based on nominal concentrations
- Key result
- Duration:
- 72 h
- Dose descriptor:
- EC50
- Effect conc.:
- 10.19 mg/L
- Nominal / measured:
- meas. (initial)
- Conc. based on:
- test mat.
- Basis for effect:
- other: Yield
- Remarks on result:
- other: EC50 based on nominal concentrations
- Details on results:
- - Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no
- Unusual cell shape: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no - Results with reference substance (positive control):
- The accuracy and reliability of the test method is demonstrated periodically as recommended by OECD Guideline No. 201 and the Council Regulation (EC) No. 761/2009. Therefore, potassium dichromate (Art. 104864) was tested as positive control (Gado, 2017).
The test item (Potassium dichromate) showed 72h EC50 of 0.91 mg/L for growth rate and 0.48 mg/L for yield. The EC50 for growth rate and yield obtained in this study are in the range of ± two standard deviation of the current historical means. - Validity criteria fulfilled:
- yes
- Conclusions:
- Under the conditions of the present study, the test item showed a 72h EC50 of 37.93 mg/L for the growth rate and 10.19 mg/L for the yield of the unicellular green alga Pseudokirchneriella subcapitata. The 72 -h EC10 value was determined to be 7.12 mg/L for growth rate.
- Executive summary:
The toxicity of the test item on the growth and growth rate of the green algae of the unicellular green alga, Pseudokirchneriella subcapitata during exposure period of 72 hours was estimated in a method according to OECD 201 under GLP. For this purpose, exponentially growing cultures of Pseudokirchneriella subcapitata were exposed to different nominal test item concentrations of 1.0, 3.2, 10.0, 31.6 and 100.0 mg/L for a period of 72 hours. The initial algae cell density in each replicate was 10 000 cells per mL. Growth of the algae was determined after 24, 48 and 72 hours exposure and compared with the growth of the control group. From the results, EC50 values for growth rate and yield were calculated. Samples of the test and control media were taken directly after preparation and then daily and stored at < -20°C until further analysis of the test item concentration via HPLC with UV detection. The purpose of the analytical part of this study was to verify the concentrations of the test item in the test medium. The quantification of the test item was performed using HPLC method with UV detection. The accuracy and reliability of the test method is demonstrated periodically as recommended by OECD Guideline No. 201 and the Commission Regulation (EU) 2016/266. Therefore, potassium dichromate was tested as positive control (Gado, 2017).
The recoveries of the test item concentrations with algae decreased in the 1.0, 3.2, 10.0 and 31.6 mg/L test media samples over the time period from approx. 95% down to < LOD of the nominal concentrations. The recoveries of the test item concentrations in the 100.0 mg/L test media sample with algae remained stable over the testing period and are between 92.8% - 94.3%. Trace amounts of a substance were detected in the undiluted control medium at all-time points. However, this peak is most likely to have its origin in a component of the undiluted control medium and is not a contaminant of the control medium by the test item. The recoveries of the test item concentrations in all test media without algae ranged from 90.6% to 102.3% from the nominal concentrations over the time period of 72h and, thus, the test item was stable in the test medium during the study. It can be concluded from the analytical results, that the test item sticks on the algae surface, resulting in a decrease of the recoveries in the samples with algae especially at lower concentrations. Therefore, it is reasonable to conclude, that the test item is chemically stable in the test medium and that the algae are sufficiently exposed to the test item at concentrations of ± 20% of the nominal concentrations during the experimental phase of the study. Therefore, the EC values were calculated based on the nominal concentrations.
In the control group, the biomass increased by a factor of 260.0 over 72 hours. Therefore, the validity criterion of increase of biomass by at least a factor of 16 within three days was fulfilled. The mean coefficient of variation of the daily growth rates in the control group (section-by-section growth rates) during 72 hours was 15.0%. According to the OECD test guideline, the mean coefficient of variation must not be higher than 35%. Thus, the validity criterion was fulfilled. The coefficient of variation of the average specific growth rates in the replicates of the control group after 72 hours was 2.0%. According to the OECD test guideline, the coefficient of variation must not be higher than 7%. Thus, the validity criterion was fulfilled.
Under the conditions of the present study, the test item showed a 72h EC50 of 37.93 mg/L for the growth rate and 10.19 mg/L for the yield of the unicellular green alga Pseudokirchneriella subcapitata. The 72 -h EC10 value was determined to be 7.12 mg/L for growth rate.
Reference
Table 1: Nominal and corresponding analytical concentrations of samples inoculated with algae
Nominal test item concentration [mg/L] |
Analytical results |
|||||||
0-h1) |
24-h |
48-h |
72-h |
|||||
Meas. Cone. [mg/L] |
[%]2) |
Meas. Cone. [mg/L] |
[%]2) |
Meas. Cone. [mg/L] |
[%]2) |
Meas. Cone. [mg/L] |
[%]2) |
|
0.0 |
0.0153) |
- |
0.0143' |
- |
0.0143) |
- |
0.0173) |
- |
1.0 |
0.957 |
95.7 |
0.015 |
1.5 |
0.016 |
1.6 |
0.016 |
1.6 |
3.2 |
3.018 |
94.3 |
1.720 |
53.8 |
0.055 |
1.7 |
0.036 |
1.1 |
10.0 |
9.424 |
94.2 |
8.462 |
84.6 |
0.000 |
<LOD |
0.000 |
<LOD |
31.6 |
29.741 |
94.1 |
29.210 |
92.4 |
0.000 |
<LOD |
0.000 |
<LOD |
100.0 |
93.143 |
93.1 |
92.812 |
92.8 |
94.342 |
94.3 |
93.081 |
93.1 |
LOD = Limit of detection (0.002 mg/L)
1) Measured without algae
2) Rounded to the first decimal place
3) Due to ingredient(s) of the algae medium, not related to test item
Table 2: Nominal and corresponding concentrations of analytical control samples without algae
Nominal test item concentration [mg/L] |
Analytical results |
|||||||
0-h |
24-h |
48-h |
72-h |
|||||
Meas. Cone. [mg/L] |
[%]1) |
Meas. Cone. [mg/L] |
[%]1) |
Meas. Cone. [mg/L] |
[%]1) |
Meas. Cone. [mg/L] |
[%]1) |
|
1.0 |
0.957 |
95.7 |
0.928 |
92.8 |
0.933 |
93.3 |
0.906 |
90.6 |
3.2 |
3.018 |
94.3 |
2.997 |
93.7 |
3.031 |
94.7 |
3.001 |
93.8 |
10.0 |
9.424 |
94.2 |
9.453 |
94.5 |
9.587 |
95.9 |
9.475 |
94.8 |
31.6 |
29.741 |
94.1 |
30.171 |
95.5 |
31.979 |
101.2 |
31.530 |
99.8 |
100.0 |
93.143 |
93.1 |
97.832 |
97.8 |
93.897 |
93.9 |
102.346 |
102.3 |
1) Rounded to the first decimal place
Table 3: EC values: For the test item, the following EC values were determined:
Parameter (0-72h) |
Growth Rate |
Yield |
EC10 [mg/L] 95% confidence interval |
7.12 (5.00-9.26) |
3.29 (1.68-4.65) |
EC20 [mg/L] 95% confidence interval |
12.64 (9.80-15.38) |
4.85 (3.00-6.35) |
EC50 [mg/L] 95% confidence interval |
37.93 (32.96 - 43.86) |
10.19 (8.12-12.82) |
Table 4: Algal Growth Measurement: Algal biomass (cell number) after 24, 48 and 72 hour exposure
Nominal concentration [mg/L] |
|
Biomass of algae (Cell number per mL*) |
|||
0.0 |
|
0 hours |
24 hours |
48 hours |
72 hours |
1.0000 |
4.8690 |
30.3480 |
246.3390 |
||
1.0000 |
4.8267 |
33.3027 |
280.4130 |
||
1.0000 |
4.9383 |
33.0687 |
269.4330 |
||
1.0000 |
4.2363 |
27.6750 |
211.9230 |
||
1.0000 |
4.7610 |
33.6960 |
286.6140 |
||
1.0000 |
4.8177 |
32.4504 |
265.0320 |
||
Mean |
1.0000 |
4.7415 |
31.7568 |
259.9590 |
|
SD |
0.00000 |
0.25442 |
2.32372 |
27.33975 |
|
CV |
0.0 |
5.4 |
7.3 |
10.5 |
|
1.0 |
|
0 hours |
24 hours |
48 hours |
72 hours |
1.0000 |
4.3317 |
32.7870 |
284.1930 |
||
1.0000 |
4.1724 |
32.5737 |
304.6680 |
||
1.0000 |
4.4397 |
34.7814 |
312.4080 |
||
Mean |
1.0000 |
4.3146 |
33.3807 |
300.4230 |
|
SD |
0.00000 |
0.13447 |
1.21772 |
14.57863 |
|
CV |
0.0 |
3.1 |
3.6 |
4.9 |
|
3.2 |
|
0 hours |
24 hours |
48 hours |
72 hours |
1.0000 |
3.3300 |
21.6936 |
187.5420 |
||
1.0000 |
3.7557 |
25.6086 |
244.2690 |
||
1.0000 |
3.6360 |
26.7813 |
243.2250 |
||
Mean |
1.0000 |
3.5739 |
24.6945 |
225.0120 |
|
SD |
0.00000 |
0.21954 |
2.66418 |
32.45417 |
|
CV |
0.0 |
6.1 |
10.8 |
14.4 |
|
10.0 |
|
0 hours |
24 hours |
48 hours |
72 hours |
1.0000 |
3.4947 |
14.7537 |
138.3867 |
||
1.0000 |
3.3660 |
12.5217 |
97.4187 |
||
1.0000 |
3.6387 |
17.2710 |
188.4717 |
||
Mean |
1.0000 |
3.4998 |
14.8488 |
141.4257 |
|
SD |
0.00000 |
0.13642 |
2.37608 |
45.60251 |
|
CV |
0.0 |
3.9 |
16.0 |
32.2 |
|
31.6 |
|
0 hours |
24 hours |
48 hours |
72 hours |
1.0000 |
2.0070 |
10.0980 |
18.3600 |
||
1.0000 |
1.7343 |
10.4904 |
14.4873 |
||
1.0000 |
1.7370 |
10.9494 |
17.8713 |
||
Mean |
1.0000 |
1.8261 |
10.5126 |
16.9062 |
|
SD |
0.00000 |
0.15667 |
0.42613 |
2.10903 |
|
CV |
0.0 |
8.6 |
4.1 |
12.5 |
|
100.0 |
|
0 hours |
24 hours |
48 hours |
72 hours |
1.0000 |
1.9377 |
2.5857 |
5.9904 |
||
1.0000 |
1.5903 |
2.1960 |
3.6567 |
||
1.0000 |
1.5507 |
2.1807 |
3.4974 |
||
Mean |
1.0000 |
1.6929 |
2.3208 |
4.3815 |
|
SD |
0.00000 |
0.21293 |
0.22954 |
1.39562 |
|
CV |
0.0 |
12.6 |
9.9 |
31.9 |
*Cell number divided by factor 10000
Table 5: Yield: Yield after 24, 48 and 72 hour exposure:
Nominal concentration [mg/L] |
Yield |
|||
0.0 |
|
24 hours |
48 hours |
72 hours |
3.8690 |
29.3480 |
245.3390 |
||
3.8267 |
32.3027 |
279.4130 |
||
3.9383 |
32.0687 |
268.4330 |
||
3.2363 |
26.6750 |
210.9230 |
||
3.7610 |
32.6960 |
285.6140 |
||
3.8177 |
31.4504 |
264.0320 |
||
Mean |
3.7415 |
30.7568 |
258.9590 |
|
SD |
0.25442 |
2.32372 |
27.33975 |
|
CV |
6.8 |
7.6 |
10.6 |
|
1.0 |
|
24 hours |
48 hours |
72 hours |
3.3317 |
31.7870 |
283.1930 |
||
3.1724 |
31.5737 |
303.6680 |
||
3.4397 |
33.7814 |
311.4080 |
||
Mean |
3.3146 |
32.3807 |
299.4230 |
|
SD |
0.13447 |
1.21772 |
14.57863 |
|
CV |
4.1 |
3.8 |
4.9 |
|
3.2 |
|
24 hours |
48 hours |
72 hours |
2.3300 |
20.6936 |
186.5420 |
||
2.7557 |
24.6086 |
243.2690 |
||
2.6360 |
25.7813 |
242.2250 |
||
Mean |
2.5739 |
23.6945 |
224.0120 |
|
SD |
0.21954 |
2.66418 |
32.45417 |
|
CV |
8.5 |
11.2 |
14.5 |
|
10.0 |
|
24 hours |
48 hours |
72 hours |
2.4947 |
13.7537 |
137.3867 |
||
2.3660 |
11.5217 |
96.4187 |
||
2.6387 |
16.2710 |
187.4717 |
||
Mean |
2.4998 |
13.8488 |
140.4257 |
|
SD |
0.13642 |
2.37608 |
45.60251 |
|
CV |
5.5 |
17.2 |
32.5 |
|
31.6 |
|
24 hours |
48 hours |
72 hours |
1.0070 |
9.0980 |
17.3600 |
||
0.7343 |
9.4904 |
13.4873 |
||
0.7370 |
9.9494 |
16.8713 |
||
Mean |
0.8261 |
9.5126 |
15.9062 |
|
SD |
0.15667 |
0.42613 |
2.10903 |
|
CV |
19.0 |
4.5 |
13.3 |
|
100.0 |
|
24 hours |
48 hours |
72 hours |
0.9377 |
1.5857 |
4.9904 |
||
0.5903 |
1.1960 |
2.6567 |
||
0.5507 |
1.1807 |
2.4974 |
||
Mean |
0.6929 |
1.3208 |
3.3815 |
|
SD |
0.21293 |
0.22954 |
1.39562 |
|
CV |
30.7 |
17.4 |
41.3 |
Table 6: Mean Specific Growth Rate - Mean specific growth rate after 24, 48 and 72 hour exposure
Nominal concentration [mg/L] |
Mean specific growth rate |
|||
0.0 |
|
24 hours |
48 hours |
72 hours |
1.583 |
1.706 |
1.836 |
||
1.574 |
1.753 |
1.879 |
||
1.597 |
1.749 |
1.865 |
||
1.444 |
1.660 |
1.785 |
||
1.560 |
1.759 |
1.886 |
||
1.572 |
1.740 |
1.860 |
||
Mean |
1.555 |
1.728 |
1.852 |
|
SD |
0.0559 |
0.0380 |
0.0369 |
|
CV |
3.6 |
2.2 |
2.0 |
|
1.0 |
|
24 hours |
48 hours |
72 hours |
1.466 |
1.745 |
1.883 |
||
1.428 |
1.742 |
1.906 |
||
1.491 |
1.775 |
1.915 |
||
Mean |
1.462 |
1.754 |
1.901 |
|
SD |
0.0313 |
0.0181 |
0.0163 |
|
CV |
2.1 |
1.0 |
0.9 |
|
3.2 |
|
24 hours |
48 hours |
72 hours |
|
1.203 |
1.539 |
1.745 |
|
|
1.323 |
1.621 |
1.833 |
|
|
1.291 |
1.644 |
1.831 |
|
Mean |
1.272 |
1.601 |
1.803 |
|
SD |
0.0622 |
0.0555 |
0.0505 |
|
CV |
4.9 |
3.5 |
2.8 |
|
|
|
24 hours |
48 hours |
72 hours |
|
|
1.251 |
1.346 |
1.643 |
|
|
1.214 |
1.264 |
1.526 |
10.0 |
|
1.292 |
1.425 |
1.746 |
|
Mean |
1.252 |
1.345 |
1.639 |
|
SD |
0.0390 |
0.0804 |
0.1101 |
|
CV |
3.1 |
6.0 |
6.7 |
|
|
24 hours |
48 hours |
72 hours |
|
|
0.697 |
1.156 |
0.970 |
|
|
0.551 |
1.175 |
0.891 |
31.6 |
|
0.552 |
1.197 |
0.961 |
|
Mean |
0.600 |
1.176 |
0.941 |
|
SD |
0.0839 |
0.0202 |
0.0432 |
|
CV |
14.0 |
1.7 |
4.6 |
|
|
24 hours |
48 hours |
72 hours |
|
|
0.662 |
0.475 |
0.597 |
|
|
0.464 |
0.393 |
0.432 |
100.0 |
|
0.439 |
0.390 |
0.417 |
|
Mean |
0.521 |
0.419 |
0.482 |
|
SD |
0.1220 |
0.0482 |
0.0996 |
|
CV |
23.4 |
11.5 |
20.7 |
Description of key information
Under the conditions of the present study, the test item showed a 72h EC50 of 37.93 mg/L for the growth rate and 10.19 mg/L for the yield of the unicellular green alga Pseudokirchneriella subcapitata. The 72h EC10 value was determined to be 7.12 mg/L for growth rate (reference 6.1.5-1).
Key value for chemical safety assessment
- EC50 for freshwater algae:
- 37.93 mg/L
- EC10 or NOEC for freshwater algae:
- 7.12 mg/L
Additional information
The toxicity of the test item on the growth and growth rate of the green algae of the unicellular green alga, Pseudokirchneriella subcapitata during exposure period of 72 hours was estimated in a method according to OECD 201 under GLP. For this purpose, exponentially growing cultures of Pseudokirchneriella subcapitata were exposed to different nominal test item concentrations of 1.0, 3.2, 10.0, 31.6 and 100.0 mg/L for a period of 72 hours. The initial algae cell density in each replicate was 10 000 cells per mL. Growth of the algae was determined after 24, 48 and 72 hours exposure and compared with the growth of the control group. From the results, EC50 values for growth rate and yield were calculated. Samples of the test and control media were taken directly after preparation and then daily and stored at < -20 °C until further analysis of the test item concentration via HPLC with UV detection. The purpose of the analytical part of this study was to verify the concentrations of the test item in the test medium. The quantification of the test item was performed using HPLC method with UV detection. The accuracy and reliability of the test method is demonstrated periodically as recommended by OECD Guideline No. 201 and the Commission Regulation (EU) 2016/266. Therefore, potassium dichromate was tested as positive control (Gado, 2017).
The recoveries of the test item concentrations with algae decreased in the 1.0, 3.2, 10.0 and 31.6 mg/L test media samples over the time period from approx. 95 % down to <LOD of the nominal concentrations. The recoveries of the test item concentrations in the 100.0 mg/L test media sample with algae remained stable over the testing period and are between 92.8 % - 94.3 %. Trace amounts of a substance were detected in the undiluted control medium at all-time points. However, this peak is most likely to have its origin in a component of the undiluted control medium and is not a contaminant of the control medium by the test item. The recoveries of the test item concentrations in all test media without algae ranged from 90.6 % to 102.3 % from the nominal concentrations over the time period of 72h and, thus, the test item was stable in the test medium during the study. It can be concluded from the analytical results, that the test item sticks on the algae surface, resulting in a decrease of the recoveries in the samples with algae especially at lower concentrations. Therefore, it is reasonable to conclude, that the test item is chemically stable in the test medium and that the algae are sufficiently exposed to the test item at concentrations of ± 20 % of the nominal concentrations during the experimental phase of the study. Therefore, the EC values were calculated based on the nominal concentrations.
In the control group, the biomass increased by a factor of 260.0 over 72 hours. Therefore, the validity criterion of increase of biomass by at least a factor of 16 within three days was fulfilled. The mean coefficient of variation of the daily growth rates in the control group (section-by-section growth rates) during 72 hours was 15.0 %. According to the OECD test guideline, the mean coefficient of variation must not be higher than 35 %. Thus, the validity criterion was fulfilled. The coefficient of variation of the average specific growth rates in the replicates of the control group after 72 hours was 2.0%. According to the OECD test guideline, the coefficient of variation must not be higher than 7%. Thus, the validity criterion was fulfilled.
Under the conditions of the present study, the test item showed a 72h EC50 of 37.93 mg/L for the growth rate and 10.19 mg/L for the yield of the unicellular green alga Pseudokirchneriella subcapitata. The 72h EC10 value was determined to be 7.12 mg/L for growth rate (reference 6.1.5-1).
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