Acetic acid, (ethylenedinitrilo)tetra-, cobalt salt

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

The study is well-documented by the publication and thus acceptable for assessment.

Qualifier:

no guideline followed

Principles of method if other than guideline:

The study is well-documented by the publication and thus acceptable for assessment.
Two algal strains were exposed to a series of cobalt concentrations and two pH levels in a randomized factorial design in 125 ml Ehrlenmeyer flasks for 5 days. Final cell densities were counted and compared with controls to determine EC30's for growth.

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

Chlamydomonas reinhardtii

Details on test organisms:

- Strain: UTCC 11, walled wild type; and UTCC 12, cell wall-less mutant
- Source (laboratory, culture collection): University of Toronto Culture Collection (UTCC), which were originally supplied in 1988 by the Chlamydomonas Genetics Center, Duke University, North Carolina
- Method of cultivation: grown in liquid medium in 125 ml Ehrlenmeyer flasks
- Acclimation period: 4 days to minimize pH shock

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

5 d

Test temperature:

23 - 25 °C

pH:

5.0 - 6.8
adjusted by MES buffer (2-(N-morpholino)-ethanesulfonic acid; pKa = 6.1)

Nominal and measured concentrations:

Nominal concentrations: 0, 5, 20, 30, 40, 50, 60, 70, 80, 100, 200 μM

Details on test conditions:

- Initial cells density: cells added as 1 ml of test culture in exponential growth phase
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

- continuous light (24 h photoperiod); 86 +/- 10 μmol/ m2 s, from Phillips F40 cool white fluorescent tubes
- Spacing factor for test concentrations: about 10 μM

Final cell densities were determined using a Coulter counter (model ZM) and were verified by counting cells from randomly chosen flasks using an Improved Neubauer haemocytometer at 10x magnification under a light microscope.

Reference substance (positive control):

not specified

Key result

Duration:

5 d

Dose descriptor:

other: EC30

Effect conc.:

51.7 µmol/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: at pH = 5.0, walled-strain

Key result

Duration:

5 d

Dose descriptor:

other: EC30

Effect conc.:

19 µmol/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: at pH = 6.8, walled strain

Key result

Duration:

5 d

Dose descriptor:

other: EC30

Effect conc.:

26.4 µmol/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: at pH = 5.0, wall-less strain

Key result

Duration:

5 d

Dose descriptor:

other: EC30

Effect conc.:

5.4 µmol/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: at pH = 6.8, wall-less strain

Details on results:

Data were analysed using multi-way analysis of variance (ANOVA; Glass et al. 1992) with significance defined at alpha = 0.05.

Validity criteria fulfilled:

not specified

Conclusions:

The EC30 values for Co2+ were determined for walled and wall-less strains of Chlamydomonas reinhardtii based on the growth rate at two different pH values (5.0 and 6.8).
At a pH value close to neutrality the EC30 values were significantly lower than at pH 5.0.
The EC30 values determined for the wild walled strain was 19.0 µmol/L and 51.7 µmol/l based on cobalt ions and 1.12 mg/L and 3.05 mg/L, respectively.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Edetic acid is known to be non-ecotoxic towards aquatic invertebrates as proved by studies. Thus, the toxicity of EDTA-CoH2 towards aquatic invertebrates is caused by the cobalt moiety only. As a worst-case approach it is assumed that the metal is fully released from the complex within short time. As proved by the evaluation of biodegradation of the substance the metal is released over longer period which lowers the concentrations of cobalt available in water and thus lowers the toxicity of the complex. Because metal ions bound in complexes are known to be less ecotoxic than the free ions, it can be concluded that the ecotoxicity of EDTA-CoH2 might be overestimated but not underestimated by this approach.

Reason / purpose for cross-reference:

read-across source

Qualifier:

no guideline followed

Principles of method if other than guideline:

The study is well-documented by the publication and thus acceptable for assessment.
Two algal strains were exposed to a series of cobalt concentrations and two pH levels in a randomized factorial design in 125 ml Ehrlenmeyer flasks for 5 days. Final cell densities were counted and compared with controls to determine EC30's for growth.

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

Chlamydomonas reinhardtii

Details on test organisms:

- Strain: UTCC 11, walled wild type; and UTCC 12, cell wall-less mutant
- Source (laboratory, culture collection): University of Toronto Culture Collection (UTCC), which were originally supplied in 1988 by the Chlamydomonas Genetics Center, Duke University, North Carolina
- Method of cultivation: grown in liquid medium in 125 ml Ehrlenmeyer flasks
- Acclimation period: 4 days to minimize pH shock

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

5 d

Test temperature:

23 - 25 °C

pH:

5.0 - 6.8
adjusted by MES buffer (2-(N-morpholino)-ethanesulfonic acid; pKa = 6.1)

Nominal and measured concentrations:

Nominal concentrations: 0, 5, 20, 30, 40, 50, 60, 70, 80, 100, 200 μM

Details on test conditions:

- Initial cells density: cells added as 1 ml of test culture in exponential growth phase
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

- continuous light (24 h photoperiod); 86 +/- 10 μmol/ m2 s, from Phillips F40 cool white fluorescent tubes
- Spacing factor for test concentrations: about 10 μM

Final cell densities were determined using a Coulter counter (model ZM) and were verified by counting cells from randomly chosen flasks using an Improved Neubauer haemocytometer at 10x magnification under a light microscope.

Reference substance (positive control):

not specified

Key result

Duration:

5 d

Dose descriptor:

other: EC30

Effect conc.:

51.7 µmol/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: at pH = 5.0, walled-strain

Key result

Duration:

5 d

Dose descriptor:

other: EC30

Effect conc.:

19 µmol/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: at pH = 6.8, walled strain

Key result

Duration:

5 d

Dose descriptor:

other: EC30

Effect conc.:

26.4 µmol/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: at pH = 5.0, wall-less strain

Key result

Duration:

5 d

Dose descriptor:

other: EC30

Effect conc.:

5.4 µmol/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: at pH = 6.8, wall-less strain

Details on results:

Data were analysed using multi-way analysis of variance (ANOVA; Glass et al. 1992) with significance defined at alpha = 0.05.

Validity criteria fulfilled:

not specified

Conclusions:

The EC30 values for Co2+ were determined for walled and wall-less strains of Chlamydomonas reinhardtii based on the growth rate at two different pH values (5.0 and 6.8).
At a pH value close to neutrality the EC30 values were significantly lower than at pH 5.0.
The EC30 values determined for the wild walled strain was 19.0 µmol/L and 51.7 µmol/l based on cobalt ions and 1.12 mg/L and 3.05 mg/L, respectively.

Based on molecular weight correction the following values were obtained:
EC30, corrected = 349.16 g/mol / 58.9 g/mol x 1.12 mg/L = 6.64 mg/L
EC30, corrected = 349.16 g/mol / 58.9 g/mol x 3.05 mg/L = 18.08 mg/L
The average EC30 value for EDTA-CoH2 for both conditions can be stated as 12.36 mg/L.
The EC50 value is higher than the EC30 value and thus can be expressed as >= 12.36 mg/L.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

The report summarizes all available information on the toxicity and ecotoxicity of edetic acid itself and also in presence of metal ions. It was prepared by an official national authority of the European Union. Thus, it is considered to be reliable as data source.

Qualifier:

no guideline required

Principles of method if other than guideline:

The report summarizes all available information on the toxicity and ecotoxicity of edetic acid itself and also in presence of metal ions. It was prepared by an official national authority of the European Union. Thus, it is considered to be reliable as data source.

GLP compliance:

not specified

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

310 mg/L

Conclusions:

The report states the following:
The apparent effects of complexing agents to algal growth are related to essential trace metal bioavailability. It was demonstrated that not the absolute EDTA concentration, but rather the ratio of the EDTA concentration to the metal cations is crucial to algae growth. With sufficient trace metal amounts, H4EDTA concentrations up to 310 mg/l caused no effects. Similar results are obtained when Fe(III)EDTA is used as test substance, due to its slow metal exchange kinetics over chelation of the nutrient metal ions is avoided. Therefore, direct effects caused by the intrinsic toxicity of EDTA are not expected in surface waters, where in nearly every case a stoichiometric surplus of metal ions is present.

Thus, the NOEC can be stated to be >= 310 mg/L.

Reference 4

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

The report summarizes all available information on the toxicity and ecotoxicity of edetic acid itself and also in presence of metal ions. It was prepared by an official national authority of the European Union. Thus, it is considered to be reliable as data source.

Reason / purpose for cross-reference:

read-across source

Qualifier:

no guideline required

Principles of method if other than guideline:

The report summarizes all available information on the toxicity and ecotoxicity of edetic acid itself and also in presence of metal ions. It was prepared by an official national authority of the European Union. Thus, it is considered to be reliable as data source.

GLP compliance:

not specified

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

310 mg/L

Conclusions:

The report states the following:
The apparent effects of complexing agents to algal growth are related to essential trace metal bioavailability. It was demonstrated that not the absolute EDTA concentration, but rather the ratio of the EDTA concentration to the metal cations is crucial to algae growth. With sufficient trace metal amounts, H4EDTA concentrations up to 310 mg/l caused no effects. Similar results are obtained when Fe(III)EDTA is used as test substance, due to its slow metal exchange kinetics over chelation of the nutrient metal ions is avoided. Therefore, direct effects caused by the intrinsic toxicity of EDTA are not expected in surface waters, where in nearly every case a stoichiometric surplus of metal ions is present.

Thus, the NOEC can be stated to be >= 310 mg/L.
It can be stated that the LC50 value for edetic acid is much higher than for cobalt salts. Thus, the aquatic toxicity of EDTA-CoH2 is determined by the cobalt moiety of the substance only.

Reference 5

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2001-03-19 to 2001-04-06

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:

1984

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot/batch No.of test material: A0102232 (01)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Stability under test conditions: assumed to be stable at storage conditions
- Storage condition of test material: at room temperature in the dark

Analytical monitoring:

yes

Details on sampling:

Samples of about 3 mL were taken from 3 control vessels and from each test vessels containing test substance at 0 24, 48 and 72 hours. The samples were stored in the freezer (<=10 °C) until analyses.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
A stock solution/suspension of the test substance was prepared as follows: an accurately measured amount of 0.6526 g of test substance was dissolved in deionized water. Exactiy 4.0 ml of a 118.5 g/L FeCI3x6H20 was added with a pipette to reach an equimolar concentration of EDTA and Fe(lll). After stirring the pH of the solution was adjusted to pH 5.2 using a 1 M NaOH Solution. The final concentration of 5.1237 g/L based on H4EDTA was reached by adding deionized water to a final volume of 100 mL. The stock Solution was stored in the refrigerator in the dark.
The test solutions were prepared by addition of the required amounts of stock Solution to the test vessels to obtain the following final nominal test concentrations: 60, 80 and 100 mg/L.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: P.subcapitata
- Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa, Institute of Freshwater Ecology, The Windermere Laboratory, Cumbria, Ambleside, United Kingdom.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23 ± 2 °C

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations of 60, 80 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer test flasks
- Type (delete if not applicable): open / closed
- Material, size, headspace, fill volume: 100 mL, closed with cotton-wool stoppers

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: jes
- Light intensity and quality: continuous uniform illumination was provided in the spectral ränge of 400 to 700 nm by using 30 W fluorescent lamps


EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: photometrically with a UVA/IS Spectrophotometer

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 60 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

79.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

48.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

99.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

60.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

In conclusion the 72 hour EC50 value for Fe(III)EDTA with P.subcapitata was greater than 100 mg/L based on nominal concentrations and greater than 60 mg/L based on the mean measured concentrations. The NOEC was 79.4 mg/L based on nominal concentrations and 48.4 mg/L based on the mean measured concentrations.

Executive summary:

The toxicity of Fe(lll)EDTA to exponentially growing Pseudokirchneriella subcapitata was determined over an exposure period of 72 hours. A test was carried out at nominal concentrations of 60, 80 and 100 mg/L Fe (lll) EDTA (concentrations represented as H4EDTA). Due to photodegradation, the Fe(lll)EDTA concentration declines during the test. The chemical analyses carried out showed that the concentration of the test compound at the end of the test had decreased to about 50 % of the concentration at the beginning of the test. The mean concentrations during the 72 hours of testing for the nominal concentrations of 60, 80 and 100 mg/L as measured by chemical analyses were 38.1, 48.4 and 60.6 mg/L, respectively. The test was conducted in a mineral salt medium in a climatized illuminated orbital incubator. The maximum variation in pH in the test media was 1.4 pH unit. In conclusion the 72 hour EC50-value for Fe(III)EDTA with P.subcapitata was greater than 100 mg/L based on nominal concentrations and greater than 60 mg/L based on the mean measured concentrations. The NOEC was 79.4 mg/L based on nominal concentrations and 48.4 mg/L based on the mean measured concentrations.

Reference 6

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Study period:

2001-03-19 to 2001-04-06

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This study is provided to support the conclusion that edetic acid is non-ecotoxic towards aquatic algae.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

1984

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot/batch No.of test material: A0102232 (01)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Stability under test conditions: assumed to be stable at storage conditions
- Storage condition of test material: at room temperature in the dark

Analytical monitoring:

yes

Details on sampling:

Samples of about 3 mL were taken from 3 control vessels and from each test vessels containing test substance at 0 24, 48 and 72 hours. The samples were stored in the freezer (<=10 °C) until analyses.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
A stock solution/suspension of the test substance was prepared as follows: an accurately measured amount of 0.6526 g of test substance was dissolved in deionized water. Exactiy 4.0 ml of a 118.5 g/L FeCI3x6H20 was added with a pipette to reach an equimolar concentration of EDTA and Fe(lll). After stirring the pH of the solution was adjusted to pH 5.2 using a 1 M NaOH Solution. The final concentration of 5.1237 g/L based on H4EDTA was reached by adding deionized water to a final volume of 100 mL. The stock Solution was stored in the refrigerator in the dark.
The test solutions were prepared by addition of the required amounts of stock Solution to the test vessels to obtain the following final nominal test concentrations: 60, 80 and 100 mg/L.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: P.subcapitata
- Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa, Institute of Freshwater Ecology, The Windermere Laboratory, Cumbria, Ambleside, United Kingdom.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23 ± 2 °C

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations of 60, 80 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer test flasks
- Type (delete if not applicable): open / closed
- Material, size, headspace, fill volume: 100 mL, closed with cotton-wool stoppers

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: jes
- Light intensity and quality: continuous uniform illumination was provided in the spectral ränge of 400 to 700 nm by using 30 W fluorescent lamps


EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: photometrically with a UVA/IS Spectrophotometer

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 60 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

79.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

48.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

99.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

60.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

In conclusion the 72 hour EC50 value for Fe(III)EDTA with P.subcapitata was greater than 100 mg/L based on nominal concentrations and greater than 60 mg/L based on the mean measured concentrations. The NOEC was 79.4 mg/L based on nominal concentrations and 48.4 mg/L based on the mean measured concentrations.

Executive summary:

 The toxicity of Fe(lll)EDTA to exponentially growing Pseudokirchneriella subcapitata was determined over an exposure period of 72 hours. A test was carried out at nominal concentrations of 60, 80 and 100 mg/L Fe (lll) EDTA (concentrations represented as H4EDTA). Due to photodegradation, the Fe(lll)EDTA concentration declines during the test. The chemical analyses carried out showed that the concentration of the test compound at the end of the test had decreased to about 50 % of the concentration at the beginning of the test. The mean concentrations during the 72 hours of testing for the nominal concentrations of 60, 80 and 100 mg/L as measured by chemical analyses were 38.1, 48.4 and 60.6 mg/L, respectively. The test was conducted in a mineral salt medium in a climatized illuminated orbital incubator. The maximum variation in pH in the test media was 1.4 pH unit. In conclusion the 72 hour EC50-value for Fe(III)EDTA with P.subcapitata was greater than 100 mg/L based on nominal concentrations and greater than 60 mg/L based on the mean measured concentrations. The NOEC was 79.4 mg/L based on nominal concentrations and 48.4 mg/L based on the mean measured concentrations.

 

It can be stated that the LC50 value for iron(III) edetic acid is much higher than for cobalt salts. Thus, the aquatic toxicity of EDTA-CoH2 is determined by the cobalt moiety of the substance.

Description of key information

The EC30 values for Co2+ were determined for walled and wall-less strains of Chlamydomonas reinhardtii based on the growth rate at two different pH values (5.0 and 6.8).

At a pH value close to neutrality the EC30 values were significantly lower than at pH 5.0.

The EC30 values determined for the wild walled strain was 19.0 µmol/L and 51.7 µmol/l based on cobalt ions and 1.12 mg/L and 3.05 mg/L, respectively.

Based on molecular weight correction the following values were obtained:

EC30, corrected = 349.16 g/mol / 58.9 g/mol x 1.12 mg/L = 6.64 mg/L

EC30, corrected = 349.16 g/mol / 58.9 g/mol x 3.05 mg/L = 18.08 mg/L

The average EC30 value for EDTA-CoH2 for both conditions can be stated as 12.36 mg/L.

The EC50 value is higher than the EC30 value and thus can be expressed as >= 12.36 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

12.36 mg/L