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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:
This study was conducted between 22 September 2016 and 10 February 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Reliability 1 is assigned because the study conducted according to OECD TG 201 in compliance with GLP, without deviations that influence the quality of the results.
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
EC No. 761/2009
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Identification: FRET 10-0367
Physical state/Appearance: Clear colorless liquid
Batch: RDGM38757
Purity: 98.3%
Expiry Date: 01 June 2018
Storage Conditions: Approximately 4 ºC in the dark
Intended use/Application: Fragrance ingredient for use in cleaners, detergents, fabric softeners and air fresheners
Analytical monitoring:
yes
Details on sampling:
The concentration and stability of the test item in the test preparations were verified by chemical analysis at 0 and 72 hours
Vehicle:
no
Details on test solutions:
Range-Finding Test
The results obtained from the preliminary media preparation trial conducted indicated that a dissolved test item concentration of approximately 29 mg/L could be obtained using a saturated solution method of preparation.

A nominal amount of test item (550 mg) was dispersed in 11 liters of culture medium with the aid of propeller stirring at approximately 1500 rpm for 24 hours. After 24 hours the stirring was stopped and any undissolved test item was removed by filtration through a 0.2 µm Sartorius Sartopore filter (first approximate 2 liters discarded in order to pre-condition the filter) to give a 100% v/v saturated solution. A series of dilutions was made from this saturated solution to give further stock solutions of 10 and 1.0% v/v saturated solution. An aliquot (900 mL) of each of the stock solutions was separately inoculated with algal suspension (6.3 mL) to give the required test concentrations of 1.0, 10 and 100% v/v saturated solution.
The test was conducted in 250 mL glass conical flasks each completely filled with test preparation and sealed with ground glass stoppers to reduce evaporation. Two replicate flasks were used for each control and test concentration.

Definitive Test
Based on the results of the range-finding test the following test concentrations were assigned to the definitive test: 1.0, 3.2, 10, 32 and 100% v/v saturated solution.

Experimental Preparation
A nominal amount of test item (550 mg) was dispersed in 11 liters of culture medium with the aid of propeller stirring at approximately 1500 rpm for 24 hours. After 24 hours the stirring was stopped and any undissolved test item was removed by filtration through a 0.2 µm Sartorius Sartopore filter (first approximate 2 liters discarded in order to pre-condition the filter) to give a 100% v/v saturated solution. A series of dilutions was made from this saturated solution to give stock solutions of 32, 10, 3.2 and 1.0% v/v saturated solution. An aliquot (1800 mL) of each of the stock solutions was separately inoculated with 9.9 mL of algal suspension to give the required test concentrations of 1.0, 3.2, 10, 32 and 100% v/v saturated solution.
The stock solutions and each of the prepared concentrations were inverted several times to ensure adequate mixing and homogeneity.

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
The test was carried out using Pseudokirchneriella subcapitata strain CCAP 278/4. Liquid cultures of Pseudokirchneriella subcapitata were obtained from the Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd, Scottish Marine Institute, Oban, Argyll, Scotland. Master cultures were maintained in the laboratory by the periodic replenishment of culture medium. The master cultures were maintained in the laboratory under constant aeration and constant illumination at 21 ± 2”C.
Prior to the start of the test sufficient master culture was added to approximately 100 mL volumes of culture media contained in conical flasks to give an initial cell density of approximately 103 cells/mL. The flasks were plugged with polyurethane foam stoppers and kept under constant agitation by orbital shaker (100 – 150 rpm) and constant illumination at 24 ± 1”C until the algal cell density was approximately 10^4 - 10^5 cells/mL.

Culture Medium
NaNO3 25.5 mg/L
MgCl2.6H2O 12.16 mg/L
CaCl2.2H2O 4.41 mg/L
MgSO4.7H2O 14.6 mg/L
K2HPO4 1.044 mg/L
NaHCO3 15.0 mg/L
H3BO3 0.186 mg/L
MnCl2.4H2O 0.415 mg/L
ZnCl2 0.00327 mg/L
FeCl3.6H2O 0.160 mg/L
CoCl2.6H2O 0.00143 mg/L
Na2MoO4.2H2O 0.00726 mg/L
CuCl2.2H2O 0.000012 mg/L
Na2EDTA.2H2O 0.30 mg/L
The culture medium was prepared using reverse osmosis purified deionized water* and the pH adjusted to 7.5 with 0.1N NaOH or HCl.
For the purposes of the range-finding and definitive tests, additional sodium bicarbonate (250 mg/L) was added to the prepared culture medium prior to use.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Hardness:
Not reported
Test temperature:
Temperature was maintained at 24 ± 1 °C throughout the test.
pH:
The pH of each control and test flask was determined at initiation of the test and after 72 hours exposure. The pH value of the control cultures was observed to increase from pH 7.8 at 0 hours to pH 10.2 at 72 hours. This increase was considered to be due to the amount of carbon dioxide required by the large number of algal cells in the log phase of growth (see Figure 1) exceeding the transfer rate of CO2 from the gaseous phase to the aqueous phase. In this situation CO2 required for photosynthesis and growth would be derived from bicarbonate in solution which results in an increase in the pH of the culture. The increase in pH after 72 hours was in excess of that recommended in the Test Guidelines (1.5 pH units after 72 hours). This was considered to have had no adverse effect on the results of the study given that the increase in cell concentration in the control cultures exceeded the validation criterion given in the Test Guidelines.
Nominal and measured concentrations:
Chemical analysis of the test preparations at 0 hours showed measured test concentrations to range from 0.41 to 43 mg/L. There was no significant change in the measured concentrations at 72 hours (0.40 to 42 mg/L) and so the results are based on 0-Hour measured test concentrations only.
Details on test conditions:

TEST SYSTEM
- Test vessel:
250 mL glass conical flasks were used. Two flasks each containing test preparation were used for the control and each treatment group.
The control group was maintained under identical conditions but not exposed to the test material.

- Initial cells density:
Pre-culture conditions gave an algal suspension in log phase growth characterised by a cell density of 9.10E+05 cells per mL. Inoculation of 1.8 litre of test medium with 9.9 mL of this algal suspension gave an initial cell density of 5E+03 cells per mL and had no significant dilution effect on the final test concentration.

- No. of vessels per concentration (replicates):
2

- No. of vessels per control (replicates):
2

- No. of vessels per vehicle control (replicates):
None

GROWTH MEDIUM
- Standard medium used: yes/no
- Detailed composition if non-standard medium was used:
NaNO3 25.5 mg/L
MgCl2.6H2O 12.16 mg/L
CaCl2.2H2O 4.41 mg/L
MgSO4.7H2O 14.6 mg/L
K2HPO4 1.044 mg/L
NaHCO3 15.0 mg/L
H3BO3 0.186 mg/L
MnCl2.4H2O 0.415 mg/L
ZnCl2 0.00327 mg/L
FeCl3.6H2O 0.160 mg/L
CoCl2.6H2O 0.00143 mg/L
Na2MoO4.2H2O 0.00726 mg/L
CuCl2.2H2O 0.000012 mg/L
Na2EDTA.2H2O 0.30 mg/L
The culture medium was prepared using reverse osmosis purified deionized water* and the pH adjusted to 7.5 with 0.1N NaOH or HCl.
For the purposes of the range-finding and definitive tests, additional sodium bicarbonate (250 mg/L) was added to the prepared culture medium prior to use.


- Photoperiod:
The flasks were sealed with vround glass stoppers and incubated (INFORS Multitron Version 2 incubator) at 24 ± 1 °C under continuous illumination (intensity approximately 7000 lux) provided by warm white lighting (380 – 730 nm) and constantly shaken at approximately 150 rpm for 72 hours.

- Light intensity and quality:
intensity approximately 7000 lux


- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]
After 72 hours the cell density of each flask was determined using a Coulter® Multisizer Particle Counter

- Results used to determine the conditions for the definitive study:
Based on the results of the range-finding test the following test concentrations were assigned to the definitive test: 1.0, 3.2, 10, 32 and 100% v/v saturated solution.

Assessments
Test Organism Observations
Samples were taken at 24, 48 and 72 hours and the cell densities determined using a Coulter® Multisizer Particle Counter. Three determinations were made for each sample. The nominally inoculated cell concentration (5.00 x 103 cells/mL) was taken as the starting cell density.
To determine the potential effect of the test item on the appearance of algal cells, a sample was removed from each test and control culture (replicates pooled) at the end of the test. The shape and size of the algal cells was inspected microscopically and any abnormalities recorded.

Water Quality Criteria
The pH of the control and each test preparation was determined at initiation of the test and after 72 hours exposure. The pH was measured using a Hach HQ30d Flexi handheld meter. The temperature within the incubator was recorded daily.
The appearance of the test media was recorded daily.

Verification of Test Concentrations
Samples were taken from the control and each test group from the bulk test preparation at 0 hours and from the pooled replicates at 72 hours for quantitative analysis. Duplicate samples were taken at 0 and 72 hours and stored frozen for further analysis if necessary.

Data Evaluation
Determination of ECx Values
For each individual test vessel (mean values for yield), percentage inhibition (arithmetic axis) was plotted against test concentration (logarithmic axis) and a line fitted by computerized interpolation using the Xlfit software package (IDBS). ECx values were then determined from the equation for the fitted line.
Where appropriate 95% confidence limits for the EC50 values were calculated, using the simplified method of evaluating dose-effect experiments of Litchfield and Wilcoxon (1949).

Statistical Analysis
One way analysis of variance incorporating Bartlett's test for homogeneity of variance (Sokal and Rohlf, 1981) and Dunnett's multiple comparison procedure for comparing several treatments with a control (Dunnett, 1955) was carried out on the growth rate and yield data after 72 hours for the control and all test concentrations to determine any statistically significant differences between the test and control groups. All statistical analyses were performed using the SAS computer software package (SAS, 1999 - 2001).

Validation Criteria
The results of the test are considered valid if the following performance criteria are met:
• The cell concentration of the control cultures must increase by a factor of at least 16 over the test period.
• The mean of the coefficients of variation of the section by section daily growth rates in the control cultures during the course of the test (days 0-1, 1-2 and 2-3) must not exceed 35%.
• The coefficient of variation of the average specific growth rate in replicate control cultures must not exceed 7%
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
9.3 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
1.3 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
4.4 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
4.1 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: Yield
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
1.3 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: Yield
Key result
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
4.4 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: Yield
Details on results:
RESULTS
Range-finding Test
The cell densities and percentage inhibition of growth values from the exposure of Pseudokirchneriella subcapitata to the test item during the range-finding test were determined
The results showed no effect on growth at the test concentration of 1.0% v/v saturated solution. However, growth was observed to be reduced at 10 and 100% v/v saturated solution.
Based on this information test concentrations of 1.0, 3.2, 10, 32 and 100% v/v saturated solution were selected for the definitive test.
Chemical analysis of the test preparations at 0 hours showed measured test concentrations to range from 0.51 to 26 mg/L. There was no significant decline in the measured concentrations at 72 hours indicating that the test item was stable under test conditions.

Definitive Test

Verification of Test Concentrations
Chemical analysis of the test preparations at 0 hours (see Annex 6) showed measured test concentrations to range from 0.41 to 43 mg/L. There was no significant change in the measured concentrations at 72 hours (0.40 to 42 mg/L) and so the results are based on 0-Hour measured test concentrations only.

Growth Data

From the data it is clear that the growth rate (r) and yield (y) of Pseudokirchneriella subcapitata (CCAP 278/4) were affected by the presence of the test item over the 72-Hour exposure period.
Accordingly the following results were determined from the data:

Inhibition of Growth Rate
ErC10 (0 - 72 h): 2.5 mg/L
ErC20 (0 - 72 h): 4.1 mg/L
ErC50 (0 - 72 h): 9.3 mg/L; 95% confidence limits 7.7 – 11 mg/L

Where ErCx is the test concentration that reduced growth rate by x%.

Statistical analysis of the growth rate data was carried out for the control and all test concentrations using one way analysis of variance incorporating Bartlett's test for homogeneity of variance (Sokal and Rohlf, 1981) and Dunnett's multiple comparison procedure for comparing several treatments with a control (Dunnett, 1955). There were no statistically significant differences between the control, 0.41 and 1.3 mg/L test concentrations (P0.05), however all other test concentrations were significantly different (P<0.05) and, therefore the "No Observed Effect Concentration" (NOEC) based on growth rate was 1.3 mg/L. Correspondingly the "Lowest Observed Effect Concentration" (LOEC) based on growth rate was 4.4 mg/L.

Inhibition of Yield
EyC10 (0 - 72 h): 3.6 mg/L
EyC20 (0 - 72 h): 3.7 mg/L
EyC50 (0 - 72 h): 4.1 mg/L; 95% confidence limits 4.0 – 4.2 mg/L

Where:
EyCx is the test concentration that reduced yield by x%.

Statistical analysis of the yield data was carried out as above. There were no statistically significant decreases in yield between the control, 0.41 and 1.3 mg/L test concentrations (P>0.05), however all other test concentrations were significantly different (P<0.05) and, therefore the "No Observed Effect Concentration" (NOEC) based on yield was 1.3 mg/L. Correspondingly the "Lowest Observed Effect Concentration" (LOEC) based on yield was 4.4 mg/L.

Validation Criteria
The following data show that the cell concentration of the control cultures increased by a factor of 101 after 72 hours. This increase was in line with the OECD Guideline that states the enhancement must be at least by a factor of 16 after 72 hours.
Mean cell density of control at 0 hours : 5.00 x 10^3 cells per mL
Mean cell density of control at 72 hours : 5.06 x 10^5 cells per mL

The mean coefficient of variation for section by section specific growth rate for the control cultures was 28% and hence satisfied the validation criterion given in the OECD Guideline which states the mean must not exceed 35%.
The coefficient of variation for average specific growth rate for the control cultures over the test period (0 – 72 h) was 3% and hence satisfied the validation criterion given in the OECD Guideline which states that this must not exceed 7%.

Observations on Cultures
All test and control cultures were inspected microscopically at 72 hours. After 72 hours there were no abnormalities detected in the control or test cultures at 0.41, 1.3 and 4.4 mg/L, however enlarged cells were observed to be present in the test cultures at 14 and 43 mg/L.

Water Quality Criteria
Temperature was maintained at 24 ± 1 ºC throughout the test.
The pH value of the control cultures was observed to increase from pH 7.8 at 0 hours to pH 10.2 at 72 hours. This increase was considered to be due to the amount of carbon dioxide required by the large number of algal cells in the log phase of growth exceeding the transfer rate of CO2 from the gaseous phase to the aqueous phase. In this situation CO2 required for photosynthesis and growth would be derived from bicarbonate in solution which results in an increase in the pH of the culture. The increase in pH after 72 hours was in excess of that recommended in the Test Guidelines (1.5 pH units after 72 hours). This was considered to have had no adverse effect on the results of the study given that the increase in cell concentration in the control cultures exceeded the validation criterion given in the Test Guidelines.

Observations on Test Item Solubility
At the start of the test all control and test cultures were observed to be clear colorless solutions. After the 72-Hour test period all control, 0.41 and 1.3 mg/L test cultures were observed to be green dispersions. The 4.4 mg/L test cultures were pale green dispersions; the 14 mg/L test cultures were extremely pale green dispersions whilst the 43 mg/L test cultures were clear colorless solutions.

Results with reference substance (positive control):
Positive Control
A positive control (Envigo Study Number FP48BQ) used potassium dichromate as the reference item at concentrations of 0.25, 0.50, 1.0, 2.0 and 4.0 mg/L.

Exposure conditions and data evaluation for the positive control were similar to those in the definitive test.

Exposure of Pseudokirchneriella subcapitata (CCAP 278/4) to the reference item gave the following results:

ErC50 (0 – 72 h) : 1.4 mg/L; 95% confidence limits 1.2 – 1.5 mg/L
EyC50 (0 – 72 h) : 0.60 mg/L; 95% confidence limits 0.52 – 0.69 mg/L

No Observed Effect Concentration (NOEC) based on growth rate: 0.25 mg/L
No Observed Effect Concentration (NOEC) based on yield: 0.25 mg/L
Lowest Observed Effect Concentration (LOEC) based on growth rate: 0.50 mg/L
Lowest Observed Effect Concentration (LOEC) based on yield: 0.50 mg/L

The results from the positive control with potassium dichromate were within the normal ranges for this reference item.

Preliminary Media Preparation Trial

1.       Saturated Solution Preparation

A nominal amount of test item (1100 mg) was dispersed, in duplicate, in 11 liters of deionized reverse osmosis water with the aid of propeller stirring at approximately 1500 rpm for periods of either 24 or 48 hours.  After stirring samples were taken for chemical analysis after the following pre-treatments:

•       Centrifugation at 10000 g for 30 minutes

•       Centrifugation at 40000 g for 30 minutes

•       Filtration through a 0.2 μm Sartorius Sartopore filter (approximately 1 liter discarded in order to pre-condition the filter)

•       Filtration through a 0.2 μm Sartorius Sartopore filter (approximately 2 liters discarded in order to pre-condition the filter)

Visual observations made on all samples indicated that undissolved test item remained and as such it was considered that the measured concentrations obtained were not a true representation of the dissolved test item concentration present.  A further saturated solution was therefore prepared whereby the initial loading rate was reduced to 50 mg/L in order to prevent over saturation of the preparations.

2.       Further Saturated Solution Preparation

A nominal amount of test item (550 mg) was dispersed, in duplicate, in 11 liters of deionized reverse osmosis water with the aid of propeller stirring at approximately 1500 rpm for periods of either 24 or 48 hours.  After stirring samples were taken for chemical analysis after the following pre-treatments:

•       Filtration through a 0.2 μm Sartorius Sartopore filter (approximately 1 liter discarded in order to pre-condition the filter)

•       Filtration through a 0.2 μm Sartorius Sartopore filter (approximately 2 liters discarded in order to pre-condition the filter)

3.       Results

Stirring Period and Treatment       Concentration Found (mg/L)

24 Hours Filtered ~ 1 liter discarded       40.0

24 Hours Filtered ~ 2 liters discarded       29.1

48 Hours Filtered ~ 1 liter discarded       38.1

48 Hours Filtered ~ 2 liters discarded       31.7

Discussion

The lower measured concentrations obtained following a 2-liter discard volume was attributed to a 1 liter discard volume being insufficient to ensure saturation of all available sites within the filter matrices.

Based on this information the test item was prepared using a saturated solution method of preparation at an initial loading rate of 50 mg/L, stirred for a period of 24 hours prior to the removal of any undissolved test item by filtration through a 0.2 μm Sartorius Sartopore filter (first approximate 2 liters discarded) to give a nominal test concentration of approximately 29 mg/L.

Validity criteria fulfilled:
yes
Remarks:
Cell concentration of the control cultures increased by a factor of 101 after 72 hours. This increase was in line with the OECD Guideline that states the enhancement must be at least by a factor of 16 after 72 hours.
Conclusions:
The effect of the test item on the growth of Pseudokirchneriella subcapitata has been investigated over a 72-Hour period and based on the 0-Hour measured test concentrations gave the following results(mg/mL):

Growth Rate EC50 9.3 NOEC 1.3 LOEC 4.4
Yield EC50 4.1 NOEC 1.3 LOEC 4.4

Executive summary:

A study was performed to assess the effect of the test item on the growth of the green alga Pseudokirchneriella subcapitata.  The method followed that described in the OECD Guidelines for Testing of Chemicals (2006) No 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" referenced as Method C.3 of Commission Regulation (EC) No 761/2009.

 Methods

Preliminary solubility work conducted indicated that it was not possible to obtain a testable solution of the test item using traditional methods of preparation e.g. ultrasonication and high shear mixing.

A preliminary media preparation trial indicated that a dissolved test item concentration of approximately 29 mg/L was obtained from a saturated solution method of preparation indicating this to be the limit of water solubility of this item under test conditions.

Following a preliminary range-finding test, Pseudokirchneriella subcapitata was exposed to solutions of the test item at nominal concentrations of 1.0, 3.2, 10, 32 and 100% v/v saturated solution (three replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1 C.  The test item solutions were prepared by stirring an excess (50 mg/L) of test item in culture medium using a propeller stirrer at approximately 1500 rpm for 24 hours.  After the stirring period any undissolved test item was removed by filtration (0.2 µm Sartorius Sartopore filter, first approximate 2 liters discarded in order to pre-condition the filter) to produce a 100% v/v saturated solution of the test item.  This saturated solution was then further diluted as necessary, to provide the remaining test groups.

Due to the volatile nature of the test item, testing was conducted in completely filled, stoppered test vessels in order to minimize possible losses due to volatilization.  Following the recommendations of published data (Herman et al 1990) in order to prevent inhibition of growth due to the restriction of gaseous exchange, additional sodium bicarbonate was added to the culture medium to provide a source of carbon dioxide for algal growth.

Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter® Multisizer Particle Counter.

Results

Analysis of the test preparations at 0 hours showed measured test concentrations to range from 0.41 to 43 mg/L.  There was no significant change in the measured concentrations at 72 hours (0.40 to 42 mg/L) and so the results are based on 0-Hour measured test concentrations only.

Exposure of Pseudokirchneriella subcapitata to the test item gave the following results based on the 0-Hour measured test concentrations:

 Response Variable  EC50 (mg/L)  95% Confidence Limits (mg/L)  No Observed Effect Concentration (NOEC) (mg/L)  Lowest Observed Effect Concentration (LOEC) (mg/L)
 Growth Rate  9.3  7.7 - 11.3  1.3  4.4
 Yield  4.1  4.0 - 4.2  1.3  4.4

                          

      

Description of key information

A study was performed to assess the effect of the test item on the growth of the green alga Pseudokirchneriella subcapitata.  The method followed that described in the OECD Guidelines for Testing of Chemicals (2006) No 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" referenced as Method C.3 of Commission Regulation (EC) No 761/2009.

Results

Analysis of the test preparations at 0 hours showed measured test concentrations to range from 0.41 to 43 mg/L.  There was no significant change in the measured concentrations at 72 hours (0.40 to 42 mg/L) and so the results are based on 0-Hour measured test concentrations only.

Exposure of Pseudokirchneriella subcapitata to the test item gave the following results based on the 0-Hour measured test concentrations:

 Response Variable  EC50 (mg/L)  95% Confidence Limits (mg/L)  No Observed Effect Concentration (NOEC) (mg/L)  Lowest Observed Effect Concentration (LOEC) (mg/L)
 Growth Rate  9.3  7.7 - 11.3  1.3  4.4
 Yield  4.1  4.0 - 4.2  1.3  4.4

               

Key value for chemical safety assessment

EC50 for freshwater algae:
9.3 mg/L
EC10 or NOEC for freshwater algae:
1.3 mg/L

Additional information