Reaction products of sodium glucoheptonate with manganese sulfate and sodium 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:

weight of evidence

Study period:

1979

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: Algae Assay Procedure Bottle Test

Version / remarks:

US EPA (1971)

Deviations:

not specified

GLP compliance:

no

Vehicle:

no

Test organisms (species):

other: Selenastrum capricornutum

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

29 d

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 ml autoclaved volumetric flask with funnel
- Aeration: air flow applied to maintain pH control
- Initial cells density: 10^6 cells/L
- No. of vessels per concentration (replicates): 5

GROWTH MEDIUM
- Standard medium used: yes, SAAM (standard algal assay medium).

TEST CONCENTRATIONS
- Range finding study: yes, coarse and fine screening tests were conducted previously.
- Test concentrations: 1 - 1000 mg/L

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

3.1 mg/L

Conc. based on:

element

Basis for effect:

other: total algal cell volume

Remarks on result:

other:

Remarks:

Duration is an approximation

Table 2: Relative total cell volume of S. capricornutum as a function of manganese spiking in coarse-screening experiment.

		S.capricornutum
	Concentration	SAAM
Spike	(mg/L)	Day 13
No spike		1.00 ± 0.10
Mn	1.0	0.89 +0.12
	10.0	0.24 + 0.04
	100.0	0
	1000.0	0

Table 3: Growth rate and average cell volume of S. capricornutum as a function of Mn spikings in fine-screeing experiments.

		Growth rate	Cell volume
	Concentration	Day 0-5	Day 14
Spike	(mg/L)	(per day)	(µm³)
None		1.35 ± 0.04	57 ± 3
Mn	1.0
	2.0	1.27 ± 0.08	62 + 5
	4.0	1.27 ±0.08	56 ± 6
	8.0	0.93 ±0.17	54 ± 4
	16.0		51 ± 4
	32.0		55 ± 8
	64.0
	256.0

Conclusions:

A 50 % reduction in the total algal cell volume of Selenastrum capricornutum in SAAM occurs in the presence of 3.1 mg manganese per liter added singly.

Executive summary:

Algal assays were conducted by Christensen et al (1979) to observe the responses of Selenastrum capricornutum and Chlorella stigmatophora to the metals manganese, copper and lead added singly or in combination to both artificial media and natural waters. Thereby, only the effects induced by manganese in artificial waters are of importance for this read-across purpose.

Growth rates and average cell volumes are given in Table 3 (please see section "Any other informatIion on results incl. tables"). While the growth rate, based on cell volume, in all cases decreased with increasing metal concentration, the average cell volume does not follow a similarly, consistent pattern. Manganese has only a slight effect on the average cell volume. It is concluded, that main effects and interactions occur for the total cell number than for the total cell volume. This means that the cell volume as a measure of the total biomass is in general less affected by manganese than the total cell number.

A 50 % reduction in the total algal cell volume of Selenastrum capricornutum in SAAM occurs in the presence of 3.1 mg manganese per liter added singly. The study was conducted for approximately 14 days, so the reported concentration of 3.1 mg/L is regarded as the 14d EC50.

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.

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

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 (72h) of > 100 mg/L and a NOEC (72h) of 100 mg/L were derived.

Executive summary:

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

not specified

Specific details on test material used for the study:

No details given.

Analytical monitoring:

yes

Details on sampling:

No details given.

Vehicle:

no

Details on test solutions:

No details given.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella 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 (72h) > 1000 mg/L (based on growth rate; nominal concentration)
NOEC (72h) = 560 mg/L (based on growth rate; nominal concentration)

Executive summary:

The acute toxicity of 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 (72h) was determined to be > 1000 mg/L while the NOEC (72h) 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

Study period:

1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: Marine Algae Assay Procedure Bottle Test

Version / remarks:

US EPA (1974)

Deviations:

yes

Remarks:

Chlorella stigmatophoare was used as test organism.

GLP compliance:

no

Vehicle:

no

Test organisms (species):

other: Chlorella stigmatophora

Test type:

not specified

Water media type:

saltwater

Limit test:

no

Total exposure duration:

29 d

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 ml autoclaved volumetric flask with funnel
- Aeration: air flow applied to maintain pH control
- Initial cells density: 10^6 cells/L
- No. of vessels per concentration (replicates): 5

GROWTH MEDIUM
- Standard medium used: yes, ASW (artificial seawater).

TEST CONCENTRATIONS
- Range finding study: yes, coarse and fine screening tests were conducted previously.
- Test concentrations: 1 - 1000 mg/L

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

50 mg/L

Conc. based on:

element

Basis for effect:

other: total algal cell volume

Remarks on result:

other:

Remarks:

Duration is an approximation

Table 2: Relative total cell volume of C. stigmatophora as a function of manganese spikings in coarse-screening experiment.

		C.stigmatophora
	Concentration	28 ppt ASW + full SAAM
Spike	(mg/L)	Day 24 nutrients
No spike		1.00 ± 0.32
Mn	1.0	1.42 + 0.70
	10.0	0.66 + 0.28
	100.0	0.48 ± 0.74
	1000.0	0 (developement of brown color)

Table 3: Growth rate and average cell volume of C. stimatophora as a function of Mn spikings in fine-screeing experiments.

		Growth rate	Cell volume
	Concentration	Day 0-10	Day 21
Spike	(mg/L)	(per day)	(µm³)
None		0.69 ± 0.02	20.7 + 2.4
Mn	1.0	0.69 ± 0.01	19.5 ± 0.3
	2.0
	4.0	0.69 ± 0.02	18.2 ± 0.5
	8.0
	16.0	0.69 ± 0.03	17.2 ± 0.4
	32.0
	64.0	0.59 ± 0.03	15.1 ± 0.3
	256.0	0.3 +0.1

Conclusions:

A 50 % reduction in the total algal cell volume of Chlorella stigmatophora in 28 ppt ASW plus full SAAM nutrients occurs in the presence of 50 mg manganese per liter added singly.

Executive summary:

Algal assays were conducted by Christensen et al (1979) to observe the responses of Selenastrum capricornutum and Chlorella stigmatophora to the metals manganese, copper and lead added singly or in combination to both artificial media and natural waters. Thereby, only the effects induced by manganese in artificial waters are of importance for this read-across purpose.

Growth rates and average cell volumes are given in Table 3 (please see section "Any other informatIion on results incl. tables"). While the growth rate, based on cell volume, in all cases decreased with increasing metal concentration, the average cell volume does not follow a similarly, consistent pattern. Manganese decreases the average cell volume slightly. It is concluded, that main effects and interactions occur for the total cell number than for the total cell volume. This means that the cell volume as a measure of the total biomass is in general less affected by manganese than the total cell number.

A 50 % reduction in the total algal cell volume of Chlorella stigmatophora in 28 ppt ASW plus full SAAM nutrients occurs in the presence of 50 mg manganese per liter added singly. The study was conducted for approximately 21 days, so the reported concentration of 50 mg/L is regarded as the 21d EC50.

Reference 5

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2003

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: scientific standard method applied.

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):

Raphidocelis subcapitata (previous names: Pseudokirchneriella 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 by 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. 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.

Reference 6

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: No standard guideline followed, two different strains of algae tested. Additionally, the documentation and given results indicate that the study was well-performed and satisfies general scientific requirements.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Algae suspensions are spread over an agar plate containing various concentrations of the test substance. After incubation, the percentage of colonies showing abnormal cells was calculated relative to total survivors.

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

Different concentrations of MnCl2*4H20 (British Drug Houses, India) were incorporated in the agar medium after autoclaving. Nutrient agar plates were prepared in basal medium for each concentration of manganese chloride (1-10 mM).

Test organisms (species):

other: Chroococcus limneticus and Plectonema boryanum

Details on test organisms:

TEST ORGANISM
- Common name: coccoid blue-green alga and filamentous blue-green alga
- Strain: Chroococcus limneticus and Plectonema boryanum
- Source (laboratory, culture collection): isolate of this laboratory, Department of Botany, Banaras Hindu University, Varanasi 221005, India (C. limneticus); Dr. R. S. Safferman, Environmental Protection Agency, Cinninnati, Ohio (U.S.A.) (P. boryanum)
- Method of cultivation: routinely grown in Allen and Arnon's medium supplemented with KNO3 (0.02 M) as a nitrogen source (C. limneticus); grown in the modified Chu No. 10 medium (P. boryanum)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

10 d

Remarks on exposure duration:

Resistant colonies of P. boryanum were scored after ten days of incubation.

Nominal and measured concentrations:

nominal concentrations at 1-10mM

Details on test conditions:

TEST SYSTEM
- Test vessel: nutrient agar plate
- No. of organisms per vessel: 0.2 ml of 2.2 * 1000 cells/ml
- No. of vessels per concentration (replicates): 3


OTHER TEST CONDITIONS
- Sterile test conditions: no data
- Photoperiod: 14 h
- Light intensity and quality: daylight fluorescent tubes
- Temperature 24 ± 1 °C

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Growth of the algae in genaral was measured turbidometrically by a Unicam SP 1300 colorimeter with a red filter (680 nm). The number of cells was determined either by haemocytometer or estimating protein content per cell. The colony counts were made under the high power magnification of a binocular microscope.

TEST CONCENTRATIONS
- Test concentrations: 1 - 10 mM

Duration:

10 d

Dose descriptor:

EC50

Effect conc.:

ca. 5.2 mmol/L

Nominal / measured:

nominal

Conc. based on:

other: Mn2+

Basis for effect:

other: count of surviving colonies

Remarks on result:

other: Results for Chroococcus limneticus

Duration:

10 d

Dose descriptor:

EC50

Effect conc.:

ca. 0.2 mmol/L

Nominal / measured:

nominal

Conc. based on:

other: Mn2+

Basis for effect:

other: count of surviving colonies

Remarks on result:

other: Results for Plectonema boryanum

Duration:

10 d

Dose descriptor:

EC10

Effect conc.:

ca. 1.4 mmol/L

Nominal / measured:

nominal

Conc. based on:

other: Mn2+

Basis for effect:

other: count of surviving colonies

Remarks on result:

other: Results for Chroococcus limneticus

Duration:

10 d

Dose descriptor:

EC10

Effect conc.:

0.03 mmol/L

Nominal / measured:

nominal

Conc. based on:

other: Mn2+

Basis for effect:

other: count of surviving colonies

Remarks on result:

other: Results for Plectonema boryanum

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): yes
- Other: asymmetry in cell division, abnormal cell enlargement
- Any stimulation of growth found in any treatment: no

Reported statistics and error estimates:

The results of three independent experiments were statistically analyzed employing a Chi2 analysis.

Validity criteria fulfilled:

not applicable

Conclusions:

Although no standard guideline was followed, two different strains of algae tested and the documentation and given results indicate that the study was well-performed and satisfies general scientific requirements. So the study is classified as reliable with restrictions and consequently, the results can considered to be reliable and used for classification.

Executive summary:

The effect of manganese chloride on Chroococcus limneticus and two mutants of Plectonema boryanum was investigated by Singh and Kashyap (1978).

In a 10 d toxicity study, cultures of Chroococcus limneticus and Plectonema boryanum were placed on nutrient agar plates with various concentrations of MnCl2 incorporated (1 -10 mM), i.e. under static conditions. The EC50 and the EC10 values based on the count of surviving colonies were 5.2 mmol/L and 1.4 mmol/L for C. limneticus and 0.2 mmol/L and 0.03 mmol/L for P. boryanum, respectively. The following abnormalities were noted: asymmetry in cell division, abnormal cell enlargement.

This toxicity study was classified as acceptable and reliable with restrictions and satisfies general scientific requirement for a 10 d toxicity study in algae.

Description of key information

There is no data available for the target substance manganese glucoheptonate on acute toxicity towards aquatic algae. However, there is data available for the source substances sodium gluconate, gluconic acid and manganese chloride. This data is used within a frame of a weight-of-evidence approach to assess the toxicity of manganese glucoheptonate (MnGHA).

The MnGHA EC50s range from 24.11 to 2222.18 mg/L for various different freshwater species and the 10d EC10s range from 12.82 to 598.28 mg/L. The key value for chemical safety assessment for freshwater algae is set to the lowest reported EC50 value of 24.11 mg/L which was obtained forSelenastrum capricornutum (Pseudokirchneriella subcapitata)within a 14 d study by Christensen et al (1979).

EC50(14d): 24.11 mg/L for Selenastrum capricornutum (Christensen et al, 1979).

Key value for chemical safety assessment

EC50 for freshwater algae:

24.11 mg/L

Additional information

gluconic acid and sodium gluconate

The toxicity of 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 72h. As final results and based on growth rate, an EC50 (7h) of > 100 mg/L and a NOEC (72h) of 100 mg/L were derived.

 

There was an additional acute toxicity study of Sodium gluconate (CAS 527-07-1) 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, Pseudokirchneriella subcapitata has been used (Biomass loading: 1 x 10 E04 cells/mL). As final results, the EC50 (72h) was determined to be >1000 mg/L while the NOEC (72h) was set to 560 mg/L based on the growth rate (nominal concentration).

 

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. subcapitata using 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 24h. 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 72h 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 72h EC50 values with 95% confidence interval. The EC50 (72h) 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.

manganese chloride

Data on the toxicity of manganese to algae and aquatic plants was reviewed. In the reviewed studies three different freshwater algae (Selenastrum capricornutum, Chroococcus limneticus and Plectonema boryanum), as well as the floating aquatic vascular plants Lemna minor (Duckweed) and one marine algae were used as test organisms. The reported effect concentrations (EC10 and EC50) for the test substances were stated as mg Mn/L.

The data on manganese compounds allows estimating a corresponding EC for manganese glucoheptonate providing that no toxicity is attributed to the glucoheptonate ion, that the absorption of manganese from this manganese compounds is 100 % and all manganese became systemically available. 

 

Algal assays were conducted by Christensen et al (1979) to observe the response of the freshwater alga Selenastrum capricornutum and the marine algae Chlorella stigmatophora to the metals manganese, copper and lead added singly or in combination to both artificial media and natural waters. Thereby, only the effects induced by manganese in artificial waters are of importance for this read-across purpose.

Growth rates and average cell volumes were assessed by the authors. While the growth rate, based on cell volume, in all cases decreased with increasing metal concentration, the average cell volume does not follow a similarly, consistent pattern. Manganese has only a slight effect on the average cell volume. It is concluded that main effects and interactions occur rather regarding to the total cell number than concerning the total cell volume. This means that the cell volume as a measure of the total biomass is less affected by manganese than the total cell number.

The marine water algae Chlorella stigmatophora showed a 50 % reduction in the total algal cell volume in 28 ppt ASW plus full SAAM (standard algal assay medium) nutrients in the presence of 50 mg manganese per liter added singly. The study was conducted for approximately 21 days, so the reported concentration of 50 mg/L is regarded as the 21d EC50. The corresponding 21d EC50 for manganese glucoheptonate is calculated to be 388.92 mg/L for Chlorella stigmatophora.

Christensen et al (1979) also assay the freshwater algae Selenastrum capricornutum in SAAM. A 50 % reduction in the total algal cell volume occurs in the presence of 3.1 mg manganese per liter added singly. The study was conducted for approximately 14 days, so the reported concentration of 3.1 mg/L is regarded as the 14d EC50. This value corresponds to a 14d EC50 of 24.11 mg/L for manganese glucoheptonate for Selenastrum capricornutum.

 

The effect of manganese chloride on Chroococcus limneticus and two mutants of Plectonema boryanum was investigated by Singh and Kashyap (1978). In a 10 d toxicity study, cultures of Chroococcus limneticus and Plectonema boryanum were placed on nutrient agar plates with various concentrations of MnCl2 incorporated (1 -10 mM), i.e. under static conditions. The EC50 and the EC10 values based on the count of surviving colonies were 5.2 mmol/L and 1.4 mmol/L for C. limneticus and 0.2 mmol/L and 0.03 mmol/L for P. boryanum, respectively. The following abnormalities were noted: asymmetry in cell division, abnormal cell enlargement. This toxicity study was classified as acceptable and reliable with restrictions and satisfies general scientific requirement for a 10 d toxicity study in algae. Although no standard guideline was followed, two different strains of algae tested and the documentation and given results indicate that the study was well-performed and satisfies general scientific requirements. So the study is classified as reliable with restrictions. The corresponding 10d EC50 for manganese glucoheptonate is 85.47 mg/L for Plectonema boryanum and 2222.18 mg/L for Chroococcus limneticus. The 10d EC10 for manganese glucoheptonate are 598.28 and 12.82 mg/L for Plectonema boryanum and Chroococcus limneticus, respectively.

 

In a 4 d acute toxicity study, the freshwater floating aquatic vascular plant Lemna minor were exposed to Manganese at 6 different concentrations under static conditions similar to OECD Guideline 221. The EC50 values based on growth rate determined by front number compared to control was 31 mg/L Manganese. This toxicity study was classified as acceptable and satisfies the guideline requirement for a Lemna Growth inhibition test with minor restrictions.

The study is classified as reliable with restrictions because of the testing similar to OECD Guideline 221 and the results indicate, that the study was well-performed and satifies general scientific requirements. Consequently, the results can be considered to be reliable. Additionally, the test organism Lemna minor broadens the spectrum of aquatic organisms and, as an additional model, allows a deeper insight in the expectable effects of the test substance on the aquatic environment. Therefore, these results should be also taken into account when assessing the need for classification. A 4d EC50 value of 31 mg/L Mn2+ was obtained. The 4d EC50 for manganese glucoheptonate is 241.13 mg/L for Lemna minor.

 

Conclusion

The MnGHA EC50s range from 24.11 to 2222.18 mg/L for various different freshwater species and the 10d EC10s range from 12.82 to 598.28 mg/L. The key value for chemical safety assessment for freshwater algae is set to the lowest reported EC50 value of 24.11 mg/L which was obtained for Selenastrum capricornutum (Pseudokirchneriella subcapitata) within a 14 d study by Christensen et al (1979).

 

Only one EC50 was obtained for marine water algae. This value is not used as key value for chemical safety assessment for marine water algae because it can not be validated in comparison with further EC values of marine water species to assess the reliability.

Table 1: Effect concentrations (EC) derived from studies performed with various manganese compounds and converted to manganese glucoheptonate (MnGHA).

Species	Duration of exposure	Dose descriptor	Mn GHA (70%) mg/L	Impact	Reference
Chlorella stigmatophora	21d	EC50	388.92	salt water	Christensen et al, 1979
Selenastrum capricornutum	14d	EC50	24.11	freshwater	Christensen et al, 1979
Chroococcus limneticus	10d	EC50	2222.18	freshwater	Singh and Kashyap, 1975
Plectonema boryanum	10d	EC50	85.47	freshwater	Singh and Kashyap, 1975
Chroococcus limneticus	10d	EC10	598.28	freshwater	Singh and Kashyap, 1975
Plectonema boryanum	10d	EC10	12.82	freshwater	Singh and Kashyap, 1975
Lemna minor	4d	EC50	241.13	freshwater	Wang, 1986