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EC number: 232-107-5 | CAS number: 7787-20-4
- 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:
- 08 February 2018 – 16 June 2018
- 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)
- Deviations:
- yes
- Remarks:
- Some analysed concentrations of test item were slightly outside the acceptable limit. This deviation does not have any impact on the study since test item was found stable in test medium and the EC50 is far from LOQ of analytical method
- GLP compliance:
- yes (incl. QA statement)
- Analytical monitoring:
- yes
- Details on sampling:
- - Concentrations: 0 (control), 0.238, 0.762, 2.44, 7.81, 25 and 80 mg/L.
- Sampling method: All the test concentrations along with the negative control were analyzed for the test item concentration at the beginning and end of test. Test item stock (100 mg/L) was analysed at the start of test.
- Sample storage conditions before analysis: not applicable - Vehicle:
- no
- Details on test solutions:
- PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Test item stock of 0.1 mg/mL (100 mg/L) was prepared by mixing 100 mg test item and making up to 1 L in a volumetric flask using test medium. To prepare test concentrations of 0.238, 0.762, 2.44, and 7.81 mg/L, 2.38, 7.62, 24.4, and 78.1 mL test item stock was mixed and made up to 1 L in a volumetric flask using test medium separately. To prepare test concentrations of 25 and 80 mg/L, 25 and 80 mg test item was mixed and made up to 1 L in a volumetric flask using test medium separately. 4.7 mL algal cell suspension was added before final volume make up for each test concentration in the volumetric flask.
- Negative control: 4.7 mL algal cell suspension was made up to 1 L using test medium.
- Positive control: A stock solution of reference substance (Potassium dichromate- K2Cr2O7) at 1 mg/mL was prepared by mixing 10 mg in 10 mL of test medium. For preparation of reference substance at 0.9 mg/L, 0.9 mL of reference substance stock was made up to 1L using test medium. 4.7 mL algal cell suspension was added just before final volume make up. - Test organisms (species):
- Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
- Details on test organisms:
- TEST ORGANISM
- Common name: green alga Pseudokirchneriella subcapitata
- Strain: ATCC 22662
- Source (laboratory, culture collection): American Type Culture Collection, P.O.Box 1549, Manassas, VA 20108, USA
- Method of cultivation: not reported
ACCLIMATION
- Acclimation period: 4 days
- Culturing media and conditions (same as test or not): OECD TG 201 medium was used. Algal cells were maintained at the test facility through sub-culturing once in 5 to 10 days from the continuous culture into fresh medium in a conical flask. These conical flasks were incubated between 21 and 25°C (±2°C) under a continuous illumination of 8000±1600 Lux.
To adapt and to ensure that the algae are in the exponential growth phase, inoculum culture was prepared by inoculating Pseudokirchneriella subcapitata of continuous/mother culture to test medium 4 days before the start of the test. The flasks were incubated inside the algal growth chamber under the test conditions.
- Any deformed or abnormal cells observed: not reported. - Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 72 h
- Post exposure observation period:
- None
- Test temperature:
- 22.1 to 22.5ºC
- pH:
- 7.78 to 7.84
- Nominal and measured concentrations:
- Nominal concentrations: 0 (control), 0.238, 0.762, 2.44, 7.81, 25 and 80 mg/L.
Mean measured concentrations (after 72 h): 0 (control), 0.09953, 0.2004, 2.206, 8.569, 21.94 and 79.67mg/L.
Nominal concentrations were considered to calculate the EC values. - Details on test conditions:
- TEST SYSTEM
- Test vessel: conical flask
- Material, size, headspace, fill volume: 250 mL capacity, 150 mL fill volume
- Aeration: The test containers were not bubble aerated.
- Initial cells density: 10E+04 cells/mL
- Control end cells density: 69.08 x 10E+04 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6 (negative) and 3 (positive)
- No. of vessels per vehicle control (replicates): Not applicable
GROWTH MEDIUM
- Standard medium used: yes (OECD TG 201 medium)
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: he OECD medium was prepared as per the OECD guideline 201.
- Culture medium different from test medium: No
- Intervals of water quality measurement: The pH of the controls and the test solutions was checked at the beginning and at the end of the test. Light intensity inside the algal chamber (at four random locations) was measured once daily using a Lux meter. Temperature inside the algal chamber was recorded once daily.
OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: No
- Photoperiod: Constant illumination
- Light intensity and quality: 6850 to 7013 Lux obtained with white fluorescent tube lights (light intensity of approximately 4000 to 10000 Lux).
EFFECT PARAMETERS MEASURED (with observation intervals if applicable): The algal biomass in each flask was determined at 24, 48 and 72 hours after the start of the test using a haemocytometer.
TEST CONCENTRATIONS
- Spacing factor for test concentrations: geometric factor of 3.2
- Justification for using less concentrations than requested by guideline: Not applicable; 6 concentrations used for the main test.
- Range finding study
- Test concentrations: 0.0 (control), 0.00001, 0.0001, 0.001, 0.01, 0.1, 1, 10 and 100 mg/L.
- Results used to determine the conditions for the definitive study: At the tested concentrations of 0.00001, 0.0001, 0.001, 0.01, 0.1, 1, 10 and 100 mg/L there was a reduction of algal cell biomass by 7.28, 12.58, 18.54, 20.53, 30.46, 65.56, 82.45 and 91.72 %, respectively. - Reference substance (positive control):
- yes
- Remarks:
- (potassium dichromate)
- Key result
- Duration:
- 72 h
- Dose descriptor:
- EC50
- Effect conc.:
- > 80 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- growth rate
- Key result
- Duration:
- 72 h
- Dose descriptor:
- EC20
- Effect conc.:
- 27.349 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- growth rate
- Remarks on result:
- other: : (fiducial limits: 9.71335 - 77.00683 mg/L)
- Key result
- Duration:
- 72 h
- Dose descriptor:
- EC10
- Effect conc.:
- 7.204 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- growth rate
- Remarks on result:
- other: (fiducial limits: 2.55845 - 20.2832 mg/L)
- Duration:
- 72 h
- Dose descriptor:
- EC50
- Effect conc.:
- 16.159 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- biomass
- Remarks on result:
- other: (fiducial limits: 12.0872 - 21.6025 mg/L)
- Duration:
- 72 h
- Dose descriptor:
- EC20
- Effect conc.:
- 2.445 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- biomass
- Remarks on result:
- other: (fiducial limits: 1.82878 - 3.26844 mg/L)
- Duration:
- 72 h
- Dose descriptor:
- EC10
- Effect conc.:
- 0.911 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- biomass
- Remarks on result:
- other: (fiducial limits: 0.6814 - 1.21781 mg/L)
- Details on results:
- - Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): Observed cells were found morphologically normal.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: none. - Results with reference substance (positive control):
- - Results with reference substance valid? Yes
- Relevant effect levels: There was 22.48% and 62.30% inhibition of average growth rate and yield of alga, respectively, in the reference substance group at 0.9 mg/L when compared to negative control. - Reported statistics and error estimates:
- The inhibition of growth was determined by calculating the ErC and EyC by Probit analysis of Finney (1971) using developed and validated computer program.
- Validity criteria fulfilled:
- yes
- Remarks:
- (increase of biomass in control during 72h>16 fold; coefficient of variation of the mean specific growth rate among replicates in control (t0-t72)<7%; the mean of the replicate coefficients of variation in section-by-section growth rate in control < 35%)
- Conclusions:
- In an Alga Growth Inhibition Test with Pseudokirchneriella subpicata green algae, the 72h-ErC50 of the test substance was determined to be higher than 80 mg/L and the 72h-ErC10 was calculated to be 7.2037 mg/L.
- Executive summary:
An Algae Growth Inhibition Test was performed with Pseudokirchneriella subpicata green algae on the test substance over a period of 72 h in static conditions according to OECD Guideline 201, following GLP. OECD medium was used for algal culturing. In the previous solubility study the test item was found soluble in OECD medium and thus no vehicle was needed. In a preliminary range finding study the per cent reduction of algal cell biomass was 7.28, 12.58, 18.54, 20.53, 30.46, 65.56, 82.45 and 91.72 %, at the tested concentrations of 0.00001, 0.0001, 0.001, 0.01, 0.1, 1, 10 and 100 mg/L, respectively. Based on these results, the definitive test was conducted with test item concentrations of 0.238, 0.762, 2.44, 7.81, 25 and 80 mg/L (factor of 3.2). Negative control consisted of test medium alone and a solution of 0.9 mg/L potassium dichromate was used as reference substance.Three replicates were performed for each concentration of the test item, along with six replicates for the negative control group and three replicates for the reference substance. A validated analytical method based on HPLC was used to monitor the concentration and stability of the active ingredient in the test solution. The analysis of test concentrations 2.44, 7.81, 25 and 80 mg/L showed an agreement with claimed concentrations of 87.77 to 99.59% at end of test (72 hour). Test concentrations of 0.238 and 0.762 mg/L were outside the acceptable limit (80-120% of nominal). This deviation does not have any impact on the study since stability test found that test item is stable in test medium between 1.08 and 108 mg/L and the EC50 is far from LOQ of analytical method. Thus, nominal concentrations were considered to calculate EC values. All validity criteria were fulfilled. Observed cells were found morphologically normal. The per cent inhibition of growth rate was 0, 1.22, 5.49, 13.8, 20.83 and 29.46 % and the percent yield inhibition was 0, 5.14, 21.05, 44.92, 59.49 and 72.34 % at the tested concentrations of 0.238, 0.762, 2.44, 7.81, 25 and 80 mg/L, respectively, when compared to the negative control. Based on these results, the growth rate inhibition effect concentrations were determined to be 72 h-ErC10 = 7.2037 mg/L, 72h-ErC20 = 27.3495 mg/L and 72 h-ErC50 > 80 mg/L, and the yield inhibition effect concentrations were 72h-EyC10 = 0.9109 mg/L, 72h-EyC20 = 2.4448 mg/L and 72h-EyC50 = 16.159 mg/L.
Reference
Table 1: Definitive Test - Cell Counts at Different Time Intervals
Group |
Treatment (mg/L) |
Replications |
Average cell counts (x 104cells/mL) |
Yield (x 104cells/ mL) at 72 h |
|||
0 h* |
24 h |
48 h |
72 h |
||||
G1 |
Negative control |
R1 |
1.00 |
5.00 |
26.75 |
67.00 |
66.00 |
R2 |
1.00 |
4.00 |
26.50 |
69.50 |
68.50 |
||
R3 |
1.00 |
5.75 |
27.00 |
68.00 |
67.00 |
||
R4 |
1.00 |
6.50 |
26.25 |
71.50 |
70.50 |
||
R5 |
1.00 |
5.50 |
28.00 |
69.25 |
68.25 |
||
R6 |
1.00 |
5.25 |
26.00 |
69.25 |
68.25 |
||
Average |
1.00 |
5.33 |
26.75 |
69.08 |
68.08 |
||
G2 |
0.238 |
R1 |
1.00 |
4.75 |
24.50 |
69.00 |
68.00 |
R2 |
1.00 |
4.50 |
26.75 |
71.50 |
70.50 |
||
R3 |
1.00 |
5.50 |
25.00 |
70.25 |
69.25 |
||
Average |
1.00 |
4.92 |
25.42 |
70.25 |
69.25 |
||
G3 |
0.762 |
R1 |
1.00 |
6.25 |
17.25 |
65.50 |
64.50 |
R2 |
1.00 |
5.50 |
18.75 |
65.00 |
64.00 |
||
R3 |
1.00 |
6.00 |
18.75 |
66.25 |
65.25 |
||
Average |
1.00 |
5.92 |
18.25 |
65.58 |
64.58 |
||
G4 |
2.44 |
R1 |
1.00 |
4.00 |
16.75 |
54.25 |
53.25 |
R2 |
1.00 |
3.50 |
18.25 |
55.25 |
54.25 |
||
R3 |
1.00 |
5.75 |
18.25 |
54.75 |
53.75 |
||
Average |
1.00 |
4.42 |
17.75 |
54.75 |
53.75 |
||
G5 |
7.81 |
R1 |
1.00 |
4.25 |
15.75 |
39.00 |
38.00 |
R2 |
1.00 |
4.25 |
15.50 |
38.75 |
37.75 |
||
R3 |
1.00 |
4.00 |
16.75 |
37.75 |
36.75 |
||
Average |
1.00 |
4.17 |
16.00 |
38.50 |
37.50 |
||
G6 |
25 |
R1 |
1.00 |
2.75 |
14.25 |
27.50 |
26.50 |
R2 |
1.00 |
3.25 |
14.75 |
29.25 |
28.25 |
||
R3 |
1.00 |
2.25 |
13.75 |
29.00 |
28.00 |
||
Average |
1.00 |
2.75 |
14.25 |
28.58 |
27.58 |
||
G7 |
80 |
R1 |
1.00 |
1.50 |
11.25 |
19.50 |
18.50 |
R2 |
1.00 |
1.25 |
11.00 |
19.25 |
18.25 |
||
R3 |
1.00 |
0.75 |
10.75 |
20.75 |
19.75 |
||
Average |
1.00 |
1.17 |
11.00 |
19.83 |
18.83 |
||
G8 |
Positive Control (0.9 mg/L K2Cr2O7) |
R1 |
1.00 |
4.25 |
6.50 |
29.50 |
28.50 |
R2 |
1.00 |
4.50 |
4.50 |
25.00 |
24.00 |
||
R3 |
1.00 |
3.50 |
4.00 |
25.50 |
24.50 |
||
Average |
1.00 |
4.08 |
5.00 |
26.67 |
25.67 |
*: 0 hour observations are based on loading of algal cells.
Table 2: Definitive Test Results – Algal Cell Biomass
Group |
Treatment (mg/L) |
Average Cell Counts (x 104cells/mL) |
|||
0 hour |
24 hour |
48 hour |
72 hour |
||
G1 |
Negative control |
1.00 |
5.33 |
26.75 |
69.08 |
G2 |
0.238 |
1.00 |
4.92 |
25.42 |
70.25 |
G3 |
0.762 |
1.00 |
5.92 |
18.25 |
65.58 |
G4 |
2.44 |
1.00 |
4.42 |
17.75 |
54.75 |
G5 |
7.81 |
1.00 |
4.17 |
16.00 |
38.50 |
G6 |
25 |
1.00 |
2.75 |
14.25 |
28.58 |
G7 |
80 |
1.00 |
1.17 |
11.00 |
19.83 |
G8 |
Reference substance (0.9 mg/L K2Cr2O7) |
1.00 |
4.08 |
5.00 |
26.67 |
Table 3: Definitive Test Results –Percent Growth Rate Inhibition
Group |
Treatment (mg/L) |
Average Cell Counts (x 104cells/mL) (0 hour) |
Average Cell Counts (x 104cells/mL) (72 hour) |
Natural log (average cell counts at 0 hour) |
Natural log (average cell counts at 72 hour) |
Growth Rate (anti log values) |
% Growth Rate Inhibition |
G1 |
Negative control |
1.00 |
69.08 |
9.21034 |
13.44561 |
0.05882 |
- |
G2 |
0.238 |
1.00 |
70.25 |
9.21034 |
13.4624 |
0.05906 |
-0.41* |
G3 |
0.762 |
1.00 |
65.58 |
9.21034 |
13.39361 |
0.05810 |
1.22 |
G4 |
2.44 |
1.00 |
54.75 |
9.21034 |
13.21312 |
0.05559 |
5.49 |
G5 |
7.81 |
1.00 |
38.50 |
9.21034 |
12.861 |
0.05070 |
13.8 |
G6 |
25 |
1.00 |
28.58 |
9.21034 |
12.56305 |
0.04657 |
20.83 |
G7 |
80 |
1.00 |
19.83 |
9.21034 |
12.19754 |
0.0415 |
29.46 |
G8 |
Reference substance (0.9 mg/L K2Cr2O7) |
1.00 |
26.67 |
9.21034 |
12.49388 |
0.0456 |
22.48 |
*: Considered as zero
Table 4: Definitive Test Results –Percent Yield Inhibition
Group |
Treatment (mg/L) |
Average Cell Counts (x 104cells/mL) (0 hour) |
Average Cell Counts (x 104cells/mL) (72 hour) |
Yield (x 104cells/mL) at 72 hours |
% Yield Inhibition |
G1 |
Negative control |
1.00 |
69.08 |
68.08 |
- |
G2 |
0.238 |
1.00 |
70.25 |
69.25 |
-1.71* |
G3 |
0.762 |
1.00 |
65.58 |
64.58 |
5.14 |
G4 |
2.44 |
1.00 |
54.75 |
53.75 |
21.05 |
G5 |
7.81 |
1.00 |
38.50 |
37.50 |
44.92 |
G6 |
25 |
1.00 |
28.58 |
27.58 |
59.49 |
G7 |
80 |
1.00 |
19.83 |
18.83 |
72.34 |
G8 |
Reference substance (0.9 mg/L K2Cr2O7) |
1.00 |
26.67 |
25.67 |
62.30 |
*: Considered as zero
Table 5: Definitive Test - Specific Growth Rate. Negative control.
Replications |
Specific Growth rates |
Replicate-mean specific growth rate |
S.D. |
% CV |
||
24 h - 0 h |
48 h - 24 h |
72 h - 48 h |
||||
R1 |
1.61 |
1.68 |
0.92 |
1.40 |
0.42 |
29.93 |
R2 |
1.39 |
1.89 |
0.96 |
1.41 |
0.47 |
32.93 |
R3 |
1.75 |
1.55 |
0.92 |
1.41 |
0.43 |
30.79 |
R4 |
1.87 |
1.40 |
1.00 |
1.42 |
0.44 |
30.6 |
R5 |
1.71 |
1.62 |
0.91 |
1.41 |
0.44 |
31.01 |
R6 |
1.66 |
1.60 |
0.98 |
1.41 |
0.38 |
26.64 |
Mean ± SD (% CV) |
1.67 ± 0.16 (9.68) |
1.62 ± 0.16 (9.94) |
0.95 ± 0.04 (3.91) |
1.41 ± 0.01 (0.49) |
- |
30.32 |
Mean coefficient of variation (% CV) for section by section specific growth rates |
30.32 |
|||||
The coefficient of variation (% CV) of average specific growth rates during the whole test period in replicate control cultures |
0.49 |
Table 6: Results of Test Concentration Analysis at the End of Test
Claimed Con |
Sample Code |
Analyzed Test Item Conc (mg/L) |
% Agreement with Claimed Conc.
|
Final Test Item Conc. |
Overall % Agreement with Claimed Conc. |
|||||
Mean |
SD |
%RSD |
Mean |
SD |
%RSD |
|||||
0.238 |
G2R1-1 |
0.09460 |
39.42 |
0.09953 |
0.00807 |
8.1 |
41.47 |
3.36 |
8.1 |
|
G2R1-2 |
0.1089 |
45.35 |
||||||||
G2R1-3 |
0.09515 |
39.65 |
||||||||
0.762 |
G3R1-1 |
0.1825 |
24.01 |
0.2004 |
0.0156 |
7.8 |
26.36 |
2.05 |
7.8 |
|
G3R1-2 |
0.2112 |
27.79 |
||||||||
G3R1-3 |
0.2074 |
27.28 |
||||||||
2.44 |
G4R1-1 |
2.264 |
92.80 |
2.206 |
0.124 |
5.6 |
90.40 |
5.09 |
5.6 |
|
G4R1-2 |
2.290 |
93.84 |
||||||||
G4R1-3 |
2.063 |
84.55 |
||||||||
7.81 |
G5R1-1 |
8.895 |
113.9 |
8.569 |
0.621 |
7.3 |
109.7 |
7.96 |
7.3 |
|
G5R1-2 |
7.853 |
100.5 |
||||||||
G5R1-3 |
8.960 |
114.7 |
||||||||
25.00 |
G6R1-1 |
19.93 |
79.70 |
21.94 |
2.42 |
11.0 |
87.77 |
9.66 |
11 |
|
G6R1-2 |
21.28 |
85.14 |
||||||||
G6R1-3 |
24.62 |
98.48 |
||||||||
80.00 |
G7R1-1 |
87.79 |
109.7 |
79.67 |
8.92 |
11 |
99.59 |
11.1 |
11 |
|
G7R1-2 |
81.09 |
101.4 |
||||||||
G7R1-3 |
70.13 |
87.66 |
||||||||
Acceptance limits: The acceptable range is 80 to 120 % of claimed concentration with ≤ 20 % of relative standard deviation (RSD) of the concentration. |
Conclusion: There was no interference in the G1 samples at the RT of the analyte. The obtained results of G2 and G3 group were out of acceptance limits (80-120%).
Description of key information
Key study. Test method according to OECD 201, GLP study. The 72h-ErC50 of the test substance to Pseudokirchneriella subpicata green algae was determined to be higher than 80 mg/L and the 72h-ErC10 was calculated to be 7.2037 mg/L.
Key value for chemical safety assessment
- EC50 for freshwater algae:
- 80 mg/L
- EC10 or NOEC for marine water algae:
- 7.204 mg/L
Additional information
Key study: An Algae Growth Inhibition Test was performed with Pseudokirchneriella subpicata green algae on the test substance over a period of 72 h in static conditions according to OECD Guideline 201, following GLP. OECD medium was used for algal culturing. In the previous solubility study the test item was found soluble in OECD medium and thus no vehicle was needed. In a preliminary range finding study the per cent reduction of algal cell biomass was 7.28, 12.58, 18.54, 20.53, 30.46, 65.56, 82.45 and 91.72 %, at the tested concentrations of 0.00001, 0.0001, 0.001, 0.01, 0.1, 1, 10 and 100 mg/L, respectively. Based on these results, the definitive test was conducted with test item concentrations of 0.238, 0.762, 2.44, 7.81, 25 and 80 mg/L (factor of 3.2). Negative control consisted of test medium alone and a solution of 0.9 mg/L potassium dichromate was used as reference substance.Three replicates were performed for each concentration of the test item, along with six replicates for the negative control group and three replicates for the reference substance. A validated analytical method based on HPLC was used to monitor the concentration and stability of the active ingredient in the test solution. The analysis of test concentrations 2.44, 7.81, 25 and 80 mg/L showed an agreement with claimed concentrations of 87.77 to 99.59% at end of test (72 hour). Test concentrations of 0.238 and 0.762 mg/L were outside the acceptable limit (80-120% of nominal). This deviation does not have any impact on the study since stability test found that test item is stable in test medium between 1.08 and 108 mg/L and the EC50 is far from LOQ of analytical method. Thus, nominal concentrations were considered to calculate EC values. All validity criteria were fulfilled. Observed cells were found morphologically normal. The per cent inhibition of growth rate was 0, 1.22, 5.49, 13.8, 20.83 and 29.46 % and the percent yield inhibition was 0, 5.14, 21.05, 44.92, 59.49 and 72.34 % at the tested concentrations of 0.238, 0.762, 2.44, 7.81, 25 and 80 mg/L, respectively, when compared to the negative control. Based on these results, the growth rate inhibition effect concentrations were determined to be 72 h-ErC10 = 7.2037 mg/L, 72h-ErC20 = 27.3495 mg/L and 72 h-ErC50 > 80 mg/L, and the yield inhibition effect concentrations were 72h-EyC10 = 0.9109 mg/L, 72h-EyC20 = 2.4448 mg/L and 72h-EyC50 = 16.159 mg/L.
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