Cesium formate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From September 7, 2010 to September 27, 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling method: The test samples were analysed( for each test concentration at 0 and 72 h) following addition of conc.entrated nitric acid (5 ml/100 ml of sample) and then if required further dilution in 5% concentrated nitric acid in test medium followed by filtration through 0.45 µm cellulose acetate filters.

- Sample storage conditions before analysis: -20⁰C prior analysis

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
The test item was dissolved directly in culture medium. Series of dilutions were made from the stock solution (180 and 56 mg/L) to give further stock solution of 18, 5.6, 1.8 and 0.56 mg/L. An aliquot (900ml) of each of the stock solution was separately inoculated with 9 ml of algal suspension. The inoculation had no significant effect on the final test concentration.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM-
- Strain: CCAP 276/20,
- Source (laboratory, culture collection): Culture collection of Algae and Protozoa(CCAP), Dunstaffnage Marine Laboratory, Oban, Argyll, Scotland
- Method of cultivation: Under constant illumination and shaking(100-150 rpm) at temperature of 24±1⁰C until the algal density was approx. 104-10 5 cells/ml

ACCLIMATION
- Culturing media and conditions (same as test or not) : Yes
- Any deformed or abnormal cells observed: No

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

No data

Hardness:

No data

Test temperature:

24±1⁰C

pH:

7.5±0.1

Dissolved oxygen:

No data

Nominal and measured concentrations:

At 0 h (mg/l):
Nominal Measured
0.56 0.506
1.8 1.84
5.6 5.33
18 18.5
56 55.2
180 191

At 72 h (mg/l)
Nominal Measured
0.56 0.465
1.8 1.74
5.6 5.17
18 17.7
56 53.7
180 186

Details on test conditions:

TEST SYSTEM-
Test vessel: Conical flask
- Type : Closed
- Material, size, headspace, fill volume: 250 ml glass conical flask ,100 ml of the test medium,plugged with polyurethane
- Aeration: Yes
- Initial cells density: 5.10 x 103 cells/ml
- Control end cells density: 1.71 x 105 cells /ml
- No. of organisms per vessel: 2.4 ml of algal suspension/500ml aliquot(preliminary range-finding study)
9 ml of algal solution /900ml of aliquot(definitive study)
- No. of vessels per concentration (replicates): 3 vessels/conc.(for both study)
- No. of vessels per control (replicates): 3 vessels/control for preliminary study
6 vessels/control for definitive study

GROWTH MEDIUM
- Standard medium used: Yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reverse osmosis purified deionized water
- Culture medium different from test medium: No

OTHER TEST CONDITIONS
- Sterile test conditions: Yes
- Adjustment of pH: Not required

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :-
Determination of cell concentrations: Electronic particle counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.1
- Range finding study: Yes (0.1, 1, 1.2, 2, 10, 100 mg/l)
- Test concentrations: 0.56, 1.8, 5.6, 18, 56, 180mg/l(definitive study)
- Results used to determine the conditions for the definitive study: Growth retardation at only 2, 10, 100mg/l

Reference substance (positive control):

yes

Remarks:

Potassium Dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

110 mg/L

Nominal / measured:

nominal

Conc. based on:

dissolved

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

56 mg/L

Nominal / measured:

nominal

Conc. based on:

dissolved

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

180 mg/L

Nominal / measured:

nominal

Conc. based on:

dissolved

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

67 mg/L

Nominal / measured:

nominal

Conc. based on:

dissolved

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

56 mg/L

Nominal / measured:

nominal

Conc. based on:

dissolved

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

180 mg/L

Nominal / measured:

nominal

Conc. based on:

dissolved

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): Yes
- Observation of abnormalities (for algal test): No

Results with reference substance (positive control):

Growth rate:
EC50: 0.65 mg/L, NOEC: 0.125 mg/L, LOE: 0.25 mg/L

Yield:
EC5: 0.28 mg/L (0.25-0.31 mg/L), NOEC: 0.125 mg/L, LOEC: 0.25 mg/L

Reported statistics and error estimates:

Statistical analysis of the growth rate data was carried out for control and all test concentrations using one way analysis of variance incorporating Bartlett’s test for homogeneity of variance and Dunnett’s multiple comparison procedure for comparing several treatment with a control.

There was no significant difference between the control, 0.56, 1.8, 5.6, 18 and 56 mg/L test concentrations (P≥0.05). However 180 mg/l concentration were significantly different( P≥0.05), and therefore NOEC based on growth data was 56 mg/l and LOEC was 180 mg/l.Statistical analysis for yield was carried out in a similar manner. There was no significant difference b/w the control,0.56,1.8,5.6,18,56 mg/l test conc.(P≥0.05),however 180 mg/l concentration were significantly different( P≥0.05), and therefore NOEC based on growth data was 56 mg/l and LOEC was 180 mg/l.

Validity criteria fulfilled:

yes

Conclusions:

Under the study conditions the following results were obtained: Growth rate: EC50: 110 mg/L, NOE: 56 mg/L, LOEC: 180mg/L and Yield: EC50: 67 mg/L (56-80 mg/L), NOEC: 56 mg/L, LOEC: 180 mg/L.

Executive summary:

A study was conducted to determine the effects of the test substance on growth of the green algae Desmodesmus subspicatus according to OECD Guideline 201, in compliance with GLP. Algae were exposed to concentrations of 0.56,1.8, 5.6,18,56 and 180 mg/L. Samples of the algal population were removed daily and cell concentration determined for each control and treatment group, using coulter multisizer particle counter. Under the study conditions the following results were obtained: Growth rate: EC50: 110 mg/L, NOE: 56 mg/L, LOEC: 180 mg/L and Yield: EC50: 67 mg/L (56-80 mg/L), NOEC: 56 mg/L, LOEC: 180 mg/L (Vryenhoef, 2010).

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From December 6, 2010 to December 26, 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling method: The test samples were analysed (for each test concentration at 0 and 72 h) following addition of concentrated nitric acid (5 ml/100 ml of sample) and then, if required, further dilution in 5% concentrated nitric acid in test medium followed by filtration through 0.45 µm cellulose acetate filters.
- Sample storage conditions before analysis: -20 ⁰C prior analysis

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
The test susbtance was dissolved directly in culture medium. Series of dilutions were made from the stock solution (180 and 56 mg/L) to give further stock solutions of 18, 5.6 and 1.8 mg/L. An aliquot (900 ml) of each of the stock solution was separately inoculated with 1.6 ml of algal suspension. The inoculation had no significant effect on the final test concentration.

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: Selenastrum capricornutum
- Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture collection of Algae and Protozoa(CCAP),Dunstaffnage Marine Laboratory,Oban,Argyll,Scotland
- Method of cultivation: Under constant illumination and shaking at temperature of 24±1⁰C

ACCLIMATION
- Culturing media and conditions (same as test or not): Yes
- Any deformed or abnormal cells observed: No,cell-debris at 180 mg/l conc.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

No

Hardness:

No data

Test temperature:

24±1°C

pH:

7.5±0.1

Dissolved oxygen:

No data

Salinity:

No data

Nominal and measured concentrations:

At 0 h,
Nominal- 18,56,180
Measured- 18.6,56.9,178
at 72 h,
Nominal-18,56,180
Measured-18.4,58,189

Details on test conditions:

TEST SYSTEM
- Test vessel: Conical flask
- Type : Closed
- Material, size, headspace, fill volume: 250 ml glass conical flask , 100 ml of the test medium,plugged with polyurethane
- Aeration : Yes
- Initial cells density:4.04 x 103 cells/ml
- Control end cells density: 7.2x105 cells /ml
- No. of organisms per vessel: 5.3 ml of algal suspension/450ml aliquot (preliminary range-finding study)
6.1 ml of algal solution /900ml of aliquot (definitive study)
- No. of vessels per concentration (replicates): 3 vessels/concentration (for both study)
- No. of vessels per control (replicates): 3 vessels/control for preliminary study
6 vessels/control for definitive study

GROWTH MEDIUM
- Standard medium used: Yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reverse osmosis purified deionized water
- Culture medium different from test medium: No

OTHER TEST CONDITIONS
- Sterile test conditions: Yes
- Adjustment of pH: Yes

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Electronic particle counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.1

- Range finding study: Yes (0.1,1,10,100 mg/L)
- Test concentrations: 1.8, 5.6, 18, 56, 180 mg/L (definitive study)
- Results used to determine the conditions for the definitive study: Growth retardation at only 100mg/L, no growth retardation at 0.1,1,10 mg/l

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

110 mg/L

Nominal / measured:

nominal

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: not applicable

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

33 mg/L

Nominal / measured:

nominal

Conc. based on:

dissolved

Basis for effect:

other: yield

Remarks on result:

other: 26-41

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

18 mg/L

Nominal / measured:

nominal

Conc. based on:

dissolved

Basis for effect:

other: growth rate and yield

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

56 mg/L

Nominal / measured:

nominal

Conc. based on:

dissolved

Basis for effect:

other: growth rate and yield

Details on results:

- Exponential growth in the control (for algal test): Yes
- Observation of abnormalities (for algal test): No

Results with reference substance (positive control):

Growth rate:
EC50: 0.82 mg/L, 95% confidence limit: 0.75-0.93 mg/L, NOEC: 0.25 mg/L, LOEC: 0.5 mg/L.

Yield:
EC50: 0.47mg/L, 95% confidence limit: 0.43-0.51 mg/L, NOEC: 0.25mg/L, LOEC: 0.5 mg/L.

Reported statistics and error estimates:

Statistical analysis of the growth rate data was carried out for control and all test concentration using one way analysis of variance incorporating Bartlett’s test for homogeneity of variance and Dunnett’s multiple comparison procedure for comparing several treatment with a control.

There was no significant difference between the control, 1.8, 5.6 and 18 mg/L test concentrations (P≥0.05), however all other test concentration were significantly different (P≥0.05). Therefore the NOEC based on growth data was 18 mg/L and the LOEC was 56 mg/L.

Statistical analysis for yield was carried out in a similar manner. There was no significant difference between the control, 1.8, 5.6 and 18 mg/L test concentratrions (P≥0.05), however all other test concentration were significantly different (P≥0.05). Therefore, the NOEC based on growth data was 18 mg/L and the LOEC was 56 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

Under the test conditions, the following results were found: for growth rate: EC50: 110 mg/L, NOEC: 18 mg/L and LOEC: 56 mg/L; for yield: EC50: 33 mg/L (26-41 mg/L), NOEC: 18 mg/L and LOEC: 56 mg/L.

Executive summary:

A study was conducted to determine the effect of the test substance on growth of the green algae Pseudokirchneriella subcapitata according to OECD Guideline 201, in compliance with GLP. Algae were exposed to the test substance at 1.8, 5.6, 18, 56 and 180 mg/L. Samples of the algal population were removed daily and cell concentrations determined for each control and treatment group using a coulter multisizer particle counter. Analysis of the 18, 56 and 180 mg/L test concentrations at 0 and 72 h showed measured concentrations to range from 99 to 105% of nominal, therefore the results were based on nominal concentrations. Under the test conditions, the following results were found: for growth rate: EC50: 110 mg/L, NOEC: 18 mg/L and LOEC: 56 mg/L; for yield: EC50: 33 mg/L (26-41 mg/L), NOEC: 18 mg/L and LOEC: 56 mg/L (Vryenhoef, 2010).

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1995

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

1. The test was conducted according to guidance still under development at the time (PARCOM guidance) and no mention of GLP is made. 2. Defined information was provided on: -Test material identity and purity -Test species details (source, culture of test species, age) -Study design (test concentration, test medium chemistry, control, number of replicates, exposure duration). No details of analytical monitoring given. -Test observation and results with calculation of EC50 values. No details of statistics and other biological observations.

Qualifier:

according to guideline

Guideline:

other: PARCOM guidance (under development) on hazard assessment of chemicals

Deviations:

not applicable

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

yes

Details on test solutions:

Stock prepared by dissolving 10 g of the substance into two culture medium, one with high EDTA (an ISO standard medium) and one with a low EDTA. These stock solutions were diluted to prepare a series of test solutions of 100 to 3200 mg/L concentration.

Test organisms (species):

Skeletonema costatum

Details on test organisms:

TEST ORGANISM
- Common name: Not reported
- Strain: No data
- Source (laboratory, culture collection): Culture collection of algae and protozoan maintained at the Scottish Marine Biological association Laboratory in Oban, Scotland, CCAP reference number 1077/5.

- Age of inoculum (at test initiation): 3 d
- Method of cultivation:Laboratory cultures were maintained in sterile pots containing autoclaved and high EDTA enriched natural sea water at constant temperature of 22 °C under constant illumination of artificial light. These cultures were renewed every fortnight and the fresh culture is used to inoculate the maintenance cultures.

ACCLIMATION
- Acclimation period:3 d
- Culturing media and conditions (same as test or not): Same as test
- Any deformed or abnormal cells observed:No abnormal cells observed. Healthy cells were selected from the laboratory culture to inoculate the starter culture.

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

None

Hardness:

No data

Test temperature:

18 - 22 °C

pH:

9.2

Dissolved oxygen:

No data on measurement

Salinity:

No data

Nominal and measured concentrations:

Nominal concentrations: 0, 100, 320, 1000 and 3200 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 140 mL glass crystalline dishes containing 100 mL test solution
- Type (delete if not applicable): Closed
- Material, size, headspace, fill volume: 250 mL Erlenmeyer flasks containing 100 mL of test medium
- Aeration: No
- Type of flow-through (e.g. peristaltic or proportional diluter): No
- Renewal rate of test solution (frequency/flow rate): No data
- Initial cells density: 5000 - 10000 cells/mL
- Control end cells density: 5000 - 10000 cells/mL
- No. of organisms per vessel: No data
- No. of vessels per concentration (replicates): Six
- No. of vessels per control (replicates): Six
- No. of vessels per vehicle control (replicates): Not relevant

GROWTH MEDIUM
- Standard medium used: Yes
First test: Standard ISO test medium with high EDTA
Second test: Medium with low EDTA

- Detailed composition if non-standard medium was used:

Low EDTA medium:

Stock solution 1
FeCl3.6H2O 16.5 µg/L
MnCl2.4H2O 605 µg/L
ZnSO4.7H2O 15 µg/L
CuSO4.5H2O 0.6 µg/L
CoCl2.6H2O 1.5 µg/L
H3BO3 17.1 mg/L
Na2EDTA 100 µg/L

Stock Solution 2
Thiamine hydrochloride 25 µg/L
Biotin 0.005 µg/L
Vit. B12 0.05 µg/L

Stock Solution 3
K3PO4 3.0 µg/L
NaNO3 50 µg/L
Na2SiO3.5H2O 14.9 µg/L

High EDTA medium:

Stock solution 1
FeCl3.6H2O 140 µg/L
MnCl2.4H2O 605 µg/L
ZnSO4.7H2O 150 µg/L
CuSO4.5H2O 0.6 µg/L
CoCl2.6H2O 1.5 µg/L
H3BO3 17.1 mg/L
Na2EDTA 15 mg/L

Stock Solution 2
Thiamine hydrochloride 25 µg/L
Biotin 0.005 µg/L
Vit. B12 0.05 µg/L

Stock Solution 3
K3PO4 3.0 µg/L
NaNO3 50 µg/L
Na2SiO3.5H2O 14.9 µg/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Sea water, local oyster hatchery
- Culture medium different from test medium: Same
- Intervals of water quality measurement: At start and at end of exposure period

OTHER TEST CONDITIONS
- Sterile test conditions: Yes
- Adjustment of pH: Yes, buffered, ph range 7.0-9.2 maintained
- Photoperiod: No, constant illumination
- Light intensity and quality: 3000 lux, no data on quality
- Salinity (for marine algae): Checked with Salinity Refractometer

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter] Electronic particle counter (Coulter Model ZM)
- Chlorophyll measurement: No
- Other: None

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Range finding study
- Test concentrations: Not applicable

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 320 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at high and low EDTA medium

Key result

Duration:

24 h

Dose descriptor:

other: EbC50

Effect conc.:

ca. 1 700 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at low EDTA medium

Remarks on result:

other: 400-2100

Key result

Duration:

48 h

Dose descriptor:

other: EbC50

Effect conc.:

ca. 920 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at low EDTA medium

Remarks on result:

other: 400-2100

Key result

Duration:

72 h

Dose descriptor:

other: EbC50

Effect conc.:

ca. 710 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at low EDTA medium

Key result

Duration:

24 h

Dose descriptor:

other: ErC50

Effect conc.:

ca. 2 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at low EDTA medium

Remarks on result:

other: 1100-1400

Key result

Duration:

48 h

Dose descriptor:

other: ErC50

Effect conc.:

ca. 1 300 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at low EDTA medium

Remarks on result:

other: 1100-1400

Key result

Duration:

72 h

Dose descriptor:

other: ErC50

Effect conc.:

ca. 1 600 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at low EDTA medium

Key result

Duration:

24 h

Dose descriptor:

other: EbC50

Effect conc.:

ca. 1 500 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at high EDTA medium

Key result

Duration:

48 h

Dose descriptor:

other: EbC50

Effect conc.:

ca. 980 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at high EDTA medium

Key result

Duration:

72 h

Dose descriptor:

other: EbC50

Effect conc.:

ca. 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at high EDTA medium

Key result

Duration:

24 h

Dose descriptor:

other: ErC50

Effect conc.:

ca. 1 900 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at high EDTA medium

Remarks on result:

other: 1700-2100

Key result

Duration:

48 h

Dose descriptor:

other: ErC50

Effect conc.:

ca. 1 700 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at high EDTA medium

Remarks on result:

other: 1500-1900

Key result

Duration:

72 h

Dose descriptor:

other: ErC50

Effect conc.:

ca. 2 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

at high EDTA medium

Remarks on result:

other: 1900-2500

Details on results:

- Exponential growth in the control (for algal test): Yes
- Observation of abnormalities (for algal test): No data
- Unusual cell shape: No data
- Colour differences: No data
- Flocculation: No data
- Adherence to test vessels: No data
- Aggregation of algal cells: No data
- Other: None
- Any stimulation of growth found in any treatment: There was stimulation in growth as measured by the chain concentration and area under the curve in 320 mg/L conc. when compared to the control.
- 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: None

Results with reference substance (positive control):

Not aplicable

Reported statistics and error estimates:

Not applicable

EbC50 and ErC50 values are given below:

End point	Time point
	24 h	48 h	72 h
Low EDTA
EbC50	1700	920	710
ErC50	2100	1300	1600
High EDTA
EbC50	1500	980	1000
ErC50	1900	1700	2200

95 % Confidence limts are given below:

920 mg/L (400-2100),

1300 mg/L (1100-1400)

1900 mg/L (1700-2100)

1700 mg/L (1500 -1900)

2200 mg/L (1900-2500)

NOEC values are given below:

High EDTA medium:

The NOEC was determined to be 320 mg/L

Low EDTA medium:

The NOEC was determined to be 320 mg/L

Reduction in growth rates relative to control are given below:

Low EDTA medium

Nominal concentration	Mean reduction in A relative to controls (%)			Mean reduction in µ relative to controls (%)
	0-24 h	0 -48 h	0 -72 h	0 -24 h	0 -48 h	0 -72 h
Control	-	-	-	-	-	-
100 mg/L	1.4	-0.33	3.6	0.5	-0.2	0.94
320 mg/L	-7.4	-2.2	-9.1	-3.5	-0.55	-2.3
1000 mg/L	13	62	76	12	31	30
3200 mg/l	87	98	99	76	98	79

High EDTA medium

Nominal concentration	Mean reduction in A relative to controls (%)			Mean reduction in µ relative to controls (%)
	0-24 h	0 -48 h	0 -72 h	0 -24 h	0 -48 h	0 -72 h
Control	-	-	-	-	-	-
100 mg/L	3.9	3.9	1.4	-2.4	-1.3	-2.0
320 mg/L	-5.0	-14	-6.8	-6	-5.3	-2.3
1000 mg/L	6.4	46	48	2.9	16	11
3200 mg/L	98	99	99	94	90	73

Water quality

The water quality monitoring revealed that the pH change during the test in the high EDTA medium (a total of 1.2 unit change) was slightly higher than that of the low EDTA medium (1 unit) and slightly higher than the ISO recommended range.

Estimation of chain length

Estimates varied from 2.7 cells/chain in the low EDTA control medium to 4.1 cells/chain in high EDTA medium.

Conclusions:

Under the study conditions effect concentrations for the test substance were as follows: using the low EDTA medium, the 24, 48 and 72 h EbC50 were 1700, 920 and 710 mg/L respectively. The 24, 48 and 72 h ErC50 were 2100, 1300 and 1600 mg/L respectively. Using the high EDTA medium, the 24, 48 and 72 h EbC50 were 500, 980 and 1000 mg/L respectively. The 24, 48 and 72 h ErC50 were 1900, 1700 and 2200 mg/L respectively. The NOEC for both types of medium was 320 mg/L.

Executive summary:

A study was conducted to determine the acute toxicity of the test substance to the marina algae Skeletonema costatum under static condition. The procedure was based on the PARCOM guidance (under development) on hazard assessment of chemicals. The algae were exposed to the test substance at 0, 100, 320, 1000 and 3200 mg/L for 72 h. Due to concerns that the levels of EDTA used in the algal test medium could influence the toxicity of cesium by the formation of metallic complexes, the test were conducted using a medium prepared according to ISO standards and a modified test medium with reduced levels of EDTA. No analytical dose verification was conducted. There was no apparent effect of EDTA on cesium toxicity. Under the study conditions, effect concentrations for the test substance were as follows: using the low EDTA medium, the 24, 48 and 72 h EbC50 were 1700, 920 and 710 mg/L, respectively. The 24, 48 and 72 h ErC50 were 2100, 1300 and 1600 mg/L, respectively. Using the high EDTA medium, the 24, 48 and 72 h EbC50 were 500, 980 and 1000 mg/L, respectively. The 24, 48 and 72 h ErC50 were 1900, 1700 and 2200 mg/L, respectively. The NOEC for both types of medium was 320 mg/L (Whale, 1995).

Description of key information

The test substance was tested in two freshwater (Selenastrum and Scenedesmus) and one marine (Skeletonema) algae species under static conditions according to OECD or PARCOM guidelines. The most sensitive species were the green algae with a 72h ErC50 of 110 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

110 mg/L

EC50 for marine water algae:

2 200 mg/L

EC10 or NOEC for freshwater algae:

18 mg/L

EC10 or NOEC for marine water algae:

320 mg/L

Additional information

A study was conducted to determine the effect of the test substance on growth of the green algae Pseudokirchneriella subcapitata according to OECD Guideline 201, in compliance with GLP. Algae were exposed to the test substance at 1.8, 5.6, 18, 56 and 180 mg/L. Samples of the algal population were removed daily and cell concentrations determined for each control and treatment group using a coulter multisizer particle counter. Analysis of the 18, 56 and 180 mg/L test concentrations at 0 and 72 h showed measured concentrations to range from 99 to 105% of nominal, therefore the results were based on nominal concentrations. Under the test conditions, the following results were found: for growth rate: EC50: 110 mg/L, NOEC: 18 mg/L and LOEC: 56 mg/L; for yield: EC50: 33 mg/L (26-41 mg/L), NOEC: 18 mg/L and LOEC: 56 mg/L (Vryenhoef, 2010).

A study was conducted to determine the effects of the test substance on growth of the green algae Desmodesmus subspicatus according to OECD Guideline 201, in compliance with GLP. Algae were exposed to concentrations of 0.56, 1.8, 5.6, 18, 56 and 180 mg/L. Samples of the algal population were removed daily and cell concentration determined for each control and treatment group, using a coulter multisizer particle counter. Analysis of the 18, 56 and 180 mg/L test concentrations at 0 and 72 h showed measured concentrations to range from 83 to 106% of nominal, therefore the results were based on nominal concentrations. Under the study conditions, the following results were obtained: Growth rate: EC50: 110 mg/L, NOE: 56 mg/L, LOEC: 180 mg/L and Yield: EC50: 67 mg/L (56-80 mg/L), NOEC: 56 mg/L, LOEC: 180 mg/L (Vryenhoef, 2010).

A study was conducted to determine the acute toxicity of the test substance to the marina algae Skeletonema costatum under static condition. The procedure was based on the PARCOM guidance (under development) on hazard assessment of chemicals. The algae were exposed to the test substance at 0, 100, 320, 1000 and 3200 mg/L for 72 h. Due to concerns that the levels of EDTA used in the algal test medium could influence the toxicity of cesium by the formation of metallic complexes, the test were conducted using a medium prepared according to ISO standards and a modified test medium with reduced levels of EDTA. No analytical dose verification was conducted. There was no apparent effect of EDTA on cesium toxicity. Under the study conditions, effect concentrations for the test substance were as follows: using the low EDTA medium, the 24, 48 and 72 h EbC50 were 1700, 920 and 710 mg/L, respectively. The 24, 48 and 72 h ErC50 were 2100, 1300 and 1600 mg/L, respectively. Using the high EDTA medium, the 24, 48 and 72 h EbC50 were 500, 980 and 1000 mg/L, respectively. The 24, 48 and 72 h ErC50 were 1900, 1700 and 2200 mg/L, respectively. The NOEC for both types of medium was 320 mg/L (Whale, 1995).