Reaction products of sodium glucoheptonate with iron sulfate and ammonium hydroxide

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:

other: OECD guideline study in compliance with GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

not specified

Remarks:

reviewed study was stated to be GLP-compliant in the report

Specific details on test material used for the study:

No details given.

Analytical monitoring:

yes

Details on sampling:

Because of precipitation, the test solutions were mixed well before sampling.

Vehicle:

not specified

Details on test solutions:

No details reported.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Strain: ATCC 22662
- Method of cultivation: sterilization

ACCLIMATION
- Culturing media and conditions (same as test or not): ATCC culture medium 625 Gorham’s medium

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

No details reported.

Hardness:

No details reported.

Test temperature:

22 – 24 °C

pH:

pH 7.04 – 8.0 at the beginning and pH 4.74 – 7.64 at the end of tests.

Dissolved oxygen:

No details reported.

Salinity:

Not applicable.

Nominal and measured concentrations:

Measured concentrations = 1.1, 2.4, 5.1, 12, 22 and 44 mg/L (Nominal concentrations at 3, 6, 13, 25, 50 and 100 mg/L) were studied. The measured
concentrations were 75 – 85 % of nominal concentrations. So, measured concentration was used in this test instead of nominal concentration.

Details on test conditions:

TEST SYSTEM
- Initial cells density: 1 x 10E4 cells/mL
- No. of vessels per concentration (replicates): 3

OTHER TEST CONDITIONS
- Light intensity and quality: 7,940 – 8,318 Lux

TEST CONCENTRATIONS
- Test concentrations:Nominal concentrations at 3, 6, 13, 25, 50 and 100 mg/L

Reference substance (positive control):

not required

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

6.9 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

3.8 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2.4 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.1 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

5.1 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

2.4 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

None reported.

Results with reference substance (positive control):

Not applicable.

Reported statistics and error estimates:

EC50 value and NOECs were calculated by Comprehensive Toxicity Data Analysis, database Software (Version 5.0) and Dunnett’s test, respectively.

Table 1. Cell density of Selenastrum capricornutum (ATCC 22662) during the test

Nominal Concentrations (mg/L)	Measured Concentrations (mg/L)	Cell density (x 10^4cell/mL)
		0 hr	24 hrs	48 hrs	72 hrs
Control	Control	1.1	2.1	24	190
3	1.1	0.92	2.5	22	130
6	2.4	1.4	2.5	26	95
13	5.1	1.1	1.4	22	120
25	12	0.84	0.55	11	1.9
50	22	0.67	0.21	0.64	0.34
100	44	0.79	0.083	0.34	0.083

Table 2. Percent inhibition of growth rates per concentration.

Nominal Concentrations (mg/L)	Measured Concentrations (mg/L)	Growth rates
		Growth rate	Relative growth rates (%)	Relative inhibition (%)
Control	Control	0.072	-	-
3	1.1	0.068	95.5	4.5
6	2.4	0.065	91.1	8.9
13	5.1	0.058	81.0	19.0
25	12	0.012	16.3	83.7
50	22	-0.047	0	100
100	44	-0.088	0	100

Nominal Concentrations (mg/L)	Measured Concentrations (mg/L)	Areas under the curve
		Areas under the curve	Relative growth rates (%)	Relative inhibition (%)
Control	Control	28,708,000	-	-
3	1.1	23,680,000	82.5	17.5
6	2.4	19,268,000	67.1	32.9
13	5.1	17,488,000	61.0	39.0
25	12	761,200	2.7	97.3
50	22	-154,796	0	100
100	44	-365,192	0	100

Table 3. pH of test solutions

Nominal Concentrations (mg/L)	Measured Concentrations (mg/L)	0 hr	72 hrs
Control	Control	7.81	7.61
3	1.1	7.72	7.44
6	2.1	7.69	7.64
13	5.1	7.24	7.51
25	12	8.00	6.86
50	22	7.5	5.48
100	44	7.04	4.74

Precipitation of test substance was observed at 12 – 44 mg/L. The condition of test solutions of 12, 22 and 44 mg/L became acidic after 72 hours. The acidic condition of test solutions affected the growth of algae.

Validity criteria fulfilled:

not specified

Remarks:

Coefficient of variation of average specific growth rates in replicate control cultures are not reported.

Conclusions:

EbC50 (72 h) value = 3.8 mg/L; NOEbC (72 h) = 1.1 mg/L; ErC50 (72 h) = 6.9 mg/L; NOErC (72 h) = 2.4 mg/L

Executive summary:

The acute toxicity of the read-across substance Iron dichloride (CAS 7758-94-3) towards algae (Selenastrum capricornutum, Strain: ATCC 22662) was determined according to OECD Guideline 201 in compliance with GLP. The test organisms were exposed to nominal concentrations of the test substance at 3, 6, 13, 25, 50 and 100 mg/L for 72 hours. Iron concentrations in the test solutions were analysed with ICP-AES (measured substance was total iron (Fe) and measured total iron concentration was converted into iron dichloride concentration in the test solution). The measured concentrations were 75 – 85 % of nominal concentrations. So, measured concentrations were used in the test instead of nominal concentration. An initial cells density of 1 x 10E4 cells/mL was used. Based on biomass, an EC50 (72 h) value of 3.8 mg/L and a NOEC (72 h) of 1.1 mg/L were estimated. Based on growth rate, the EC50 (72 h) was 6.9 mg/L while the NOEC (72 h) was 2.4 mg/L.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The substance has only been tested at 100 and 1000 mg/L because this test has been made on the basis of an older test according to a German norm; The inhibition level was thus expectable and the test concentrations limited to 100 and 1000 mg/L; read-across

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

The substance has only been tested at 100 and 1000 mg/L.

GLP compliance:

not specified

Remarks:

reviewed study was stated to be GLP-compliant in the report

Specific details on test material used for the study:

No details given.

Analytical monitoring:

yes

Details on sampling:

No details provided.

Vehicle:

not specified

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Sample preparation: stock solution in redistilled water.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: CHODAT (strain No 86.81 SAG)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

No details reported.

Hardness:

No details reported.

Test temperature:

Test 1: 22.7-24.8°C 
Test 2: 23.4-27.9°C

pH:

pH maximal difference between 0 and 72 hours: 0.3

Dissolved oxygen:

No details reported.

Salinity:

Not applicable.

Nominal and measured concentrations:

No details reported.

Details on test conditions:

TEST SYSTEM
- Test vessel: flasks
- Type (delete if not applicable): For test 2, the procedure has been modified by covering the test vessels with glass petri dishes to prevent contamination by micro-organisms.
- Initial cells density: 10 x 10E4 algae/mL
- No. of vessels per concentration (replicates):Test 1: 3 flasks with test item and 6 flasks without test item were prepared. Test 2: 3 flasks with 100 mg/L, 3 flasks with 1000 mg/L and 6 flasks without test item.
- No. of vessels per control (replicates): 6

OTHER TEST CONDITIONS
- Photoperiod: illuminated with 4 parallel set universal white fluorescent tubes of approximately 65 cm above the level of the tested media
- Light intensity and quality: 8900-9300 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: counting chamber

TEST CONCENTRATIONS
- Test concentrations: Test 1: 1000 mg/L (invalid); Test 2: 100 and 1000 mg/L

Reference substance (positive control):

not required

Duration:

72 h

Dose descriptor:

NOEC

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.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

No details reported.

Results with reference substance (positive control):

Not applicable.

Reported statistics and error estimates:

No details reported.

Test 1 : 1000 mg/L
not valid -  a decrease of the test item concentration was observed and therefore the test could not meet the stability requirements.

Cell growth inhibition : 85%
Average specific growth rate inhibition: 55%
---------------------

Test 2 : 100 mg/L and 1000 mg/L
Cell growth inhibition : no inhibition at 100 mg/L; 70% inhibition at 1000 mg/L

Average specific growth rate inhibition: no inhibition at 100 mg/L

42% inhibition at 1000 mg/L
----------------------------------------

Cell concentration increase in controls: factor 65.9 after 72 h

Validity criteria fulfilled:

not specified

Remarks:

Details such as coefficient of variation (average specific growth rates) are not reported.

Conclusions:

As final results and based on growth rate, an EC50 (72 h) of > 100 mg/L and a NOEC (72 h) of 100 mg/L were derived.

Executive summary:

The toxicity of the read-across substance Sodium gluconate (CAS 527-07-1) towards algae has been determined according to OECD Guideline 201 in compliance with GLP. Two tests have been performed. In the first test, 1000 mg/L of the test item have been tested. However, a decrease of the test item concentration was observed and therefore the test could not meet the stability requirements. Conclusively, a second test with 100 and 1000 mg/L test concentration was performed. Desmodesmus subspicatus CHODAT (strain No 86.81 SAG) was used as test organism. An initial cell density of 10 x 10E4 algae/mL was applied. For the second test, 3 flasks with 100 mg/L, 3 flasks with 1000 mg/L and 6 flasks without test item were used. The common OECD procedure has been modified by covering the test vessels with glass petri dishes to prevent contamination by micro-organisms. After 24, 48 and 72 hours, cell concentration was determined using a microscope with a counter chamber (8 fields counted). No cell growth inhibition at 100 mg/L was determined. At 1000 mg/L, 70% cell growth inhibition was observed. For the average specific growth rate, no inhibition at 100 mg/L but 42% inhibition at 1000 mg/L was determined. The cell concentrations in controls increased by a factor of 65.9 after 72 h. As final results and based on growth rate, an EC50 (72 h) of > 100 mg/L and a NOEC (72 h) of 100 mg/L were derived.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: study conducted according to OECD guidelines; quality assurance and GLP certificates; read-across

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

not specified

Remarks:

reviewed study was stated to be GLP-compliant in the report

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No details given.

Analytical monitoring:

yes

Details on sampling:

No details given.

Vehicle:

no

Details on test solutions:

No details given.

Test organisms (species):

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

Details on test organisms:

No details given.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

No details reported.

Hardness:

No details reported.

Test temperature:

23+/- 2°C

pH:

No details reported.

Dissolved oxygen:

No details reported.

Salinity:

not applicable

Nominal and measured concentrations:

Measured concentrations of the test substance in the test solutions at the beginning of exposure were +/-20 % of the nominal concentrations.

Details on test conditions:

TEST SYSTEM
- Biomass loading: 1 x 10 E04 cells/mL

OTHER TEST CONDITIONS
- Photoperiod: continuous (+/- 20% at the surface of the test solutions)
- Light intensity and quality: 4000 lux

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: 0 (control), 100, 180, 320, 560, 1000 mg/L (nominal concentrations)
- Results used to determine the conditions for the definitive study: A range-finding test was conducted before the definitive test to enable the above-mentioned concentration range in the definitive test.

Reference substance (positive control):

not required

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

560 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

No details reported.

Results with reference substance (positive control):

Not applicable.

Reported statistics and error estimates:

No details reported.

Cell growth inhibition at 1000 mg/L = 25.4 %

Growth rate inhibition (24-48 h) at 1000 mg/L = 7.6%

Growth rate inhibition (24-72 h) at 1000 mg/L = 9.0 %

50% growth inhibition concentration by comparison of areas
under the growth curves:

EbC50 (O-72 h): > 1000 mg/L
NOECb (0-72 h): 560 mg/L
----------------------------------------------------
50% growth inhibition concentration by comparison of growth
rates:

ErC50 (24 -48 h): > 1000 mg/L 
ErC50 (24-72 h): > 1000 mg/L
NOECr (24-72h) : 560 mg/L
NOECr (24-48h) : 560 mg/L

Color of the test solutions were observed with naked eye and the cell shapes of algae were observed through the microscope.  The test solutions were green at 24 hours after the start of exposure. Afterwards, the color of the test solutions showed a tendency to get more greenish with the passage of time.

No unusual cell shapes of algae and no agglutination were observed at the end of exposure and the algae looked normal compared to the control.

Validity criteria fulfilled:

not specified

Remarks:

Increase of biomass in control unknown.

Conclusions:

EC50 (72 h) > 1000 mg/L (based on growth rate; nominal concentration)
NOEC (72 h) = 560 mg/L (based on growth rate; nominal concentration)

Executive summary:

The acute toxicity of the read-across substance Sodium gluconate (CAS 527-07-1) towards algae was determined according to OECD Guideline 201 in compliance with GLP.

A range-finding test was conducted prior to the definitive test to enable the following concentrations in the definitive test: 0 (control), 100, 180, 320, 560, 1000 mg/L (nominal concentrations). Measured concentrations of the test substance in the test solutions at the beginning of exposure were +/-20 % of the nominal concentrations. As test organism, Pseudokirchnerella subcapitata has been used (Biomass loading: 1 x 10 E04 cells/mL).

As final results, the EC50 (72 h) was determined to be > 1000 mg/L while the NOEC (72 h) was set to 560 mg/L based on the growth rate (nominal concentration).

Reference 4

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: scientific standard method applied; read-across

Qualifier:

according to guideline

Guideline:

other: Finnish standard SFS 5072 (1986, Toxicity test with pure culture of algae)

Deviations:

not specified

GLP compliance:

no

Specific details on test material used for the study:

No details given.

Analytical monitoring:

not specified

Details on sampling:

No details given.

Vehicle:

no

Details on test solutions:

Stock solutions (0.05 M) of Gluconic acid were prepared by dissolving it with water-HCl solution (19.8 mL water + 200 µl 37% HCl) to a final
volume of 20.0 mL. After complete dissolution of the chelating agent pH was adjusted to 7.2 with 5 M and 1 M NaOH.

Test organisms (species):

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

Details on test organisms:

No details given.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

No details given.

Hardness:

No details given.

Test temperature:

22 ± 1°C

pH:

No details given.

Dissolved oxygen:

No details given.

Salinity:

Not applicable.

Nominal and measured concentrations:

No details given.

Details on test conditions:

TEST SYSTEM
- Test vessel: Flasks

OTHER TEST CONDITIONS
- Light intensity and quality: 5000 lx

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
- Determination of cell concentrations: The growth was estimated with in vivo fluorescence of chlorophyll (Labsystems, Fluoroskan Ascent).

TEST CONCENTRATIONS
- Test concentrations: 1000 mg/L was the highest concentration tested.

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

76 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

No details given.

Results with reference substance (positive control):

Not applicable.

Reported statistics and error estimates:

No details given.

Validity criteria fulfilled:

not specified

Remarks:

Exact description of applied bioassay is lacking.

Conclusions:

EC50 (72 h) = 76 mg/L (based on growth rate)

Executive summary:

Acute toxicity of four relatively new chelating agents and their equimolar manganese and cadmium complexes was studied. The chelating agents studied were gluconic acid (GA), β-alaninediacetic acid (ADA), diethylenetriaminepentakismethylenephosphonic acid (DTPMP), and nitrilotriacetic acid (NTA).

The bioassay with R. subcapitata using gluconic acid (CAS 526-95-4) was performed according to a Finnish standard SFS 5072 (1986, Toxicity test with pure culture of algae). At the time of an inoculation, the alga was in its exponential growth phase. During the test, the flasks were shaken in every 24 h. The volume in all tests was 10 mL and illumination intensity was set to 5000 lx. Temperature was maintained at 22 ± 1°C throughout the 72-h

test. Two simultaneous experiments were performed for each test concentration and the highest concentration of chelating agents was

1000 mg/L. The growth was estimated with in vivo fluorescence of chlorophyll (Labsystems, Fluoroskan Ascent) and the results obtained

from the bioassay are expressed as 72-h EC50 values with 95% confidence interval. The EC50 (72 h) value for gluconic acid is reported as 76 mg/L.

R. subcapitata proved the most sensitive to these compounds compared to Daphnia magna and Photobacterium phosphoreum.

Description of key information

There is no data available for the target substance iron glucoheptonate (CAS 23351 -51 -1) on acute toxicity towards algae. However, there is data available for the read-across substances sodium gluconate (CAS 527 -07 -01), gluconic acid (CAS 526 -95 -4) and iron dichloride (CAS 7758-94-3). This data is used within a frame of a weight-of-evidence approach to assess the toxicity of iron glucoheptonate.

The ErC50 and NOErC (72 h) value of 6.9 mg/L and 2.4 mg/L reported in a study with iron dichloride on Selenastrum capricornutum (OECD SIDS, 2004) were converted to the target substance FeGHA. The outcome is an ErC50 (72 h) value of 21.52 mg/L and a NOErC of 7.48 mg/L.

The ErC50 and NOErC (72 h) values reported for Sodium gluconate on Desmodesmus subspicatus were 100 mg/L and > 100 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

21.52 mg/L

EC10 or NOEC for freshwater algae:

7.48 mg/L

Additional information

There is no data available for the target substance iron glucoheptonate (CAS 23351 -51 -1) on acute toxicity towards algae. However, there is data available for the read-across substances sodium gluconate (CAS 527 -07 -01), gluconic acid (CAS 526 -95 -4) and iron dichloride (CAS 7758-94-3). This data is used within a frame of a weight-of-evidence approach to assess the toxicity of iron glucoheptonate.

 

Referring to the first weight-of-evidence study, the toxicity of the read-across substance Sodium gluconate (CAS 527-07-1) towards algae has been determined according to OECD Guideline 201 in compliance with GLP (OECD SIDS, 2004). Two tests have been performed. In the first test, 1000 mg/L of the test item have been tested. However, a decrease of the test item concentration was observed and therefore the test could not meet the stability requirements. Conclusively, a second test with 100 and 1000 mg/L test concentration was performed. Desmodesmus subspicatus CHODAT (strain No 86.81 SAG) was used as test organism. An initial cell density of 10 x 10E4 algae/mL was applied. For the second test, 3 flasks with 100 mg/L, 3 flasks with 1000 mg/L and 6 flasks without test item were used. The common OECD procedure has been modified by covering the test vessels with glass petri dishes to prevent contamination by micro-organisms. After 24, 48 and 72 hours, cell concentration was determined using a microscope with a counter chamber (8 fields counted). No cell growth inhibition at 100 mg/L was determined. At 1000 mg/L, 70% cell growth inhibition was observed. For the average specific growth rate, no inhibition at 100 mg/L but 42% inhibition at 1000 mg/L was determined. The cell concentrations in controls increased by a factor of 65.9 after 72 h. As final results and based on growth rate, an EC50 (72 h) of > 100 mg/L and a NOEC (72 h) of 100 mg/L were derived.

With regard to the second weight-of-evidence study, the acute toxicity of the read-across substance Iron dichloride (CAS 7758-94-3) towards algae (Selenastrum capricornutum, Strain: ATCC 22662) was determined according to OECD Guideline 201 in compliance with GLP (OECD SIDS, 2004). The test organisms were exposed to nominal concentrations of the test substance at 3, 6, 13, 25, 50 and 100 mg/L for 72 hours. Iron concentrations in the test solutions were analysed with ICP-AES (measured substance was total iron (Fe) and measured total iron concentration was converted into iron dichloride concentration in the test solution). The measured concentrations were 75 – 85 % of nominal concentrations. So, measured concentrations were used in the test instead of nominal concentration. An initial cells density of 1 x 10E4 cells/mL was used. Based on biomass, an EC50 (72 h) value of 3.8 mg/L and a NOEC (72 h) of 1.1 mg/L were estimated. Based on growth rate, the EC50 (72 h) was 6.9 mg/L while the NOEC (72 h) was 2.4 mg/L.

Further weight-of-evidence is provided by the acute toxicity of the read-across substance Sodium gluconate (CAS 527-07-1) towards algae. This was determined according to OECD Guideline 201 in compliance with GLP (OECD SIDS, 2004). A range-finding test was conducted prior to the definitive test to enable the following concentrations in the definitive test: 0 (control), 100, 180, 320, 560, 1000 mg/L (nominal concentrations). Measured concentrations of the test substance in the test solutions at the beginning of exposure were +/-20 % of the nominal concentrations. As test organism, Pseudokirchnerella subcapitata has been used (Biomass loading: 1 x 10 E04 cells/mL). As final results, the EC50 (72 h) was determined to be > 1000 mg/L while the NOEC (72 h) was set to 560 mg/L based on the growth rate (nominal concentration).

In addition, the acute toxicity of four relatively new chelating agents and their equimolar manganese and cadmium complexes was studied (Silanpää et al., 2003). The chelating agents studied were gluconic acid (GA),β-alaninediacetic acid (ADA), diethylenetriaminepentakismethylenephosphonic acid (DTPMP), and nitrilotriacetic acid (NTA). The bioassay with R. subcapitatausing gluconic acid was performed according to a Finnish standard SFS 5072 (1986, Toxicity test with pure culture of algae). At the time of an inoculation, the alga was in its exponential growth phase. During the test, the flasks were shaken in every 24 h. The volume in all tests was 10 mL and illumination intensity was set to 5000 lx. Temperature was maintained at 22 ± 1°C throughout the 72-h test. Two simultaneous experiments were performed for each test concentration and the highest concentration of chelating agents was 1000 mg/L. The growth was estimated with in vivo fluorescence of chlorophyll (Labsystems, Fluoroskan Ascent) and the results obtained from the bioassay are expressed as 72-h EC50 values with 95% confidence interval. The EC50 (72 h) value for gluconic acid is reported as 76 mg/L. R. subcapitata proved the most sensitive to these compounds compared to Daphnia magna and Photobacterium phosphoreum.

Derivation of effective concentrations for Iron glucoheptonate (CAS 23351-51-1)

There are two 4 studies available for source substances sodium gluconate, gluconic acid and iron dichloride. Since it is expected that toxicity of the target substance is rather triggered by the iron cation, data on the metal salt are considered for the Chemical Safety Assessment.

 

An EC50 (72 h) of > 100 mg/L and a NOEC (72 h) of 100 were determined for the substance Sodium gluconate (OECD SIDS, 2004). By consideration of the molecular weights of the read-across substance sodium gluconate (MW = 218.14 g/mol) and the target substance iron glucoheptonate (MW = 354.8 g/mol; trihydrated form), the EC50 and NOEC value for the read-across substance can be converted in order to account for the target substance.

100 mg/L x 354.8 g/mol / 218.14 g/mol = 162.65 mg/L

The calculated EC50 (72 h) value of > 162.65 mg/L as well as the NOEC (72 h) of 162.65 mg/L for the target substance will be used for the Chemical Safety Assessment.

 

The EC50 (72 h) value for Iron dichloride was determined to be 6.9 mg/L while the NOEC (72 h) is reported to be 2.4 mg/L (both based on growth rate; OECD SIDS, 2004). Since these values refers to the compound itself and not only to the metal ion, a conversion is necessary. By consideration of the molecular weights of Iron dichloride (126.751 g/mol) and Iron (55.85 g/mol), the EC50 value for Iron is calculated as follows:

6.9 mg/L x 55.85 g/mol / 126.751 g/mol = 3.04 mg Fe/L

The EC50 of target substance FeGHA was calculated with regard to the molecular weight by the following equation

MW Fe in FeGHA = 55.84 g/mol

MW FeGHA = 300.8 g/mol

EC (FeGHA) in target = EC (Fe) in source / 55.84 x 300.8

EC (Fe) in source = 3.04 mg/L

EC (FeGHA) in target = 3.04 / 55.84 x 300.8 = 16.35 mg/L

Purity: 76 %

16.35 / 0.76 = 21.52 mg/L

The calculated EC50 (72 h) value of 21.52 mg/L for the target substance will be used for the Chemical Safety Assessment.

 

By consideration of the molecular weights of Iron dichloride (126.751 g/mol) and Iron (55.85 g/mol), the NOEC value for Iron is calculated analogously.

2.4 mg/L x 55.85 g/mol / 126.751 g/mol = 1.06 mg Fe/L

The NOEC of target substance FeGHA was calculated with regard to the molecular weight by the following equation

EC (FeGHA) in target = 1.06 / 55.84 x 300.8 = 5.69 mg/L

Purity: 76 %

5.69 / 0.76 = 7.48 mg/L

The calculated NOEC (72 h) value of 7.48 mg/L for the target substance will be used for the Chemical Safety Assessment.