Reaction products of sodium glucoheptonate with manganese sulfate and sodium hydroxide

Toxicity to other aquatic organisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to other aquatic vertebrates

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test was not performed on a standard species or according standard guideline, no data on corresponding cation or raw data was given. However, the provided data indicate that the test was well-performed and satisfies general scientific requirements.

Qualifier:

no guideline available

Principles of method if other than guideline:

Spirostomum ambiguum were placed in a 24 well multiwell plate, 10 protozoae / well. They were exposed in darkness over a period of 24 h and 48 h to various concentrations of the test item in triplicates. Two kinds of test responses were observed: (1) different deformations (morphological changes) and (2) lethal response. On this basis two values were calculated for each row of the microplate:
EC50: the concentration producing different deformations of 50% of the test organisms
LC50: the concentration producing lethal response of 50% of the test organisms

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
Each test was one control and five toxicant’s concentrations with three duplicates per concentration.
Dilution of the sample (logarithmic progression) was made directly in the plate. For this purpose, the following amount of diluent and sample was added to all four cells in each column: 0, 0.44, 0.68, 0.82, 0.90, 1.00 ml of diluent and 1.00, 0.56, 0.32, 0.18, 0.10, 0 ml of sample.

Test organisms (species):

other: Spirostomum ambiguum

Details on test organisms:

TEST ORGANISM
- Common name: Spirostomum ambiguum
- Source: The strain was originally collected in Kampinos National Park near Warsaw and has been cultured in laboratory for more than 20 years
- Culturing the Spirostomum ambiguum: S. ambiguum was routinely cultured in 5-1 aquariums containing 4 L of natural, unpolluted water originating from a very deep source (pH = 7.5; total hardness 150 mg CaCO3/L). Cultures were maintained at 20–25°C in darkness. Every 4 weeks, two-thirds of the water in the aquarium was replaced with fresh water.

ACCLIMATION
- Type and amount of food: flaked oats and dried alder leaves (50:1)
- Feeding frequency: once / week

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Remarks on exposure duration:

Protozoan were observed after 24h and 48h

Hardness:

150 mg CaCO3/L

Test temperature:

25°C

pH:

7.5

Details on test conditions:

TEST SYSTEM
- Test vessel: 24 well (6 x 4) polystyrene multiwell plate
- No. of organisms per vessel: 10 cells per well
- No. of vessels per concentration (replicates): 3 wells
- No. of vessels per control (replicates): 3 wells

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Tyrod solution

OTHER TEST CONDITIONS
- Adjustment of pH: water had a pH = 7.5
- Photoperiod: 24h darkness

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Two kinds of test responses were observed after 24h and 48h: (1) different deformations, which means morphological changes such as shortening, bending of the cell, and so forth; and (2) lethal response (L), spherical deformation and autolysis. On this basis two values were calculated for each row of the microplate:
EC50: the concentration producing different deformations of 50% of the test organisms, and LC50: the concentration producing lethal response of 50% of the test organisms.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: test solutions were prepared with 0, 0.44, 0.68, 0.82, 0.90, 1.00 ml of diluent and 1.00, 0.56, 0.32, 0.18, 0.10, 0 ml of sample
- Range finding study: yes
- Test concentrations: serial dilution (2X)
- Results used to determine the conditions for the definitive study: Concentrations to the definitive test were then chosen: between 0 and 100% lethality of S. ambiguum.

Reference substance (positive control):

not specified

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

92.8 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Mn2+

Basis for effect:

morphology

Remarks:

different deformations

Remarks on result:

other: SD 44.7 mg/L

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

148 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Mn2+

Basis for effect:

mortality

Remarks on result:

other: SD 15.5 mg/L

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

109 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Mn2+

Basis for effect:

morphology

Remarks:

different deformations

Remarks on result:

other: SD 66.3 mg/L

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

146 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Mn2+

Basis for effect:

mortality

Remarks on result:

other: SD 19.5 mg/L

Reported statistics and error estimates:

Mean values (EC50 and LC50) ± SD were calculated for the microplate.

Validity criteria fulfilled:

not applicable

Conclusions:

The test was considered to be reliable with restrictions, and therefore the results can considered to be trustworthy. Since Spirostomum ambiguum serves as an additional species to assess the possible hazard of the test item to the environment, the same criteria for classification or non-classification should apply as for algae and other aquatic plants.
EC50 values of 92.8 +/- 44.7 mg/L and 109 +/- 66.3 mg/L are obtained after 24h and 48h, respectively. The reported LC50(24h) is 148 +/- 15.5 mg/L, the LC50(48h) is 146 +/- 19.5 mg/L.

Executive summary:

In a 24 h / 48 h toxicity study, ciliated protozoa (Spirostomum ambiguum) were exposed to various concentrations of Mn2+ under static conditions. EC50 values of 92.8 +/- 44.7 mg/L and 109 +/- 66.3 mg/L are obtained after 24h and 48h, respectively. The reported LC50(24h) is 148 +/- 15.5 mg/L, the LC50(48h) is 146 +/- 19.5 mg/L.

This toxicity study was classified as acceptable and reliable with restrictions and satisfies general scientific requirements.

Reference 2

Endpoint:

toxicity to other aquatic vertebrates

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
Please refer to read-across statement attached under section 13 of this IUCLID file.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The toxicity of glucoheptonate complexes is driven by the supplied metal cation that can affect mineral balance of the organism, while no toxicity is attributed to the organic part of the molecule - glucoheptonate moiety - up to considerable amounts. The stability constant of manganese glucoheptonate is low, the chelate is a weak complex at normal environmental pH range (4-9) (Alekseev et al., 1998; please refer to the read-across statement). Thus, it is expected to dissociate in aquatic environments. The released equimolar amount of manganese from manganese glucoheptonate is assumed to determine its toxicity to other aquatic invertebrates. In this regard, the toxicity of manganese originated from another manganese compound could provide additional information on toxicity of manganese glucoheptonate. Therefore, the data on manganese sulfate is presented here as source of data for the target substance manganese glucoheptonate to address the toxicity of the metal cation.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The source substance is manganese sulfate with a purity of > 98 %.
Information on purity of the registered substance is provided in the target record under "Test material" as confidential. The calculation of a hazard value for manganese glucoheptonate is based on 66 % content of manganese glucoheptonate in the registered product. Another component is sodium sulfate, which is considered not to impact the toxicity to invertebrates of the target substance to a significant degree. Therefore, the manganese ion is the only ecotoxicologically relevant component of the registered substance.

3. ANALOGUE APPROACH JUSTIFICATION
As announced in the hypothesis for the read-across, manganese glucoheptonate is expected to dissociate in aquatic environments (at normal pH range 4-9). Manganese sulfate is a salt that fully dissociates in water, too. However, the amount of manganese released from manganese glucoheptonate and from sulfate is different because the molecular masses of these compounds are different. Also the proportion of manganese to glucoheptonate or to sulfate anions will be different. As a result, more manganese will be released from the salt manganese sulfate than from manganese glucoheptonate. Thus, the data on manganese sulfate represent worst case for manganese glucoheptonate.

4. DATA MATRIX
attached in section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

1 h

Dose descriptor:

EC50

Effect conc.:

209.6 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

other: fluorescence

Duration:

9 h

Dose descriptor:

IC50

Effect conc.:

1 633.5 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

other: growth inhibition

Calculation of the EC50(1h) for manganese glucoheptonate for Tetrahymena pyriformis:

Molecular weight of manganese glucoheptonate (dimer, containing 2 manganese atoms per mol): 598.28 g/mol

Molecular weight of manganese: 54.94 g/mol

 

The weight of 1 mol manganese glucoheptonate is more than the weight of 1 mol of manganese. Thus, the corresponding amount of manganese glucoheptonate is more than that of manganese:

EC50 for manganese: 26.95 mg/L

EC50 for manganese glucoheptonate: 26.95 mg/L of manganese corresponds to (598.28 g/mol x 26.95 mg/L)/54.94 g/mol/2 = 146.7 mg/L.

 

The concentration of manganese glucoheptonate is 70%, therefore, the EC50 has to be recalculated: 146.7 mg/L/70% x 100% = 209.6 mg/L.

 

The calculated EC50(1h) value for manganese glucoheptonate for Tetrahymena pyriformis is 209.6 mg/L.

 

The further calculations are done accordingly.

Conclusions:

The reported EC50(1h) corresponds to a value of 209.6 ± 18.3 mg/L and the IC50(9h) is 1633.5 mg/L for Mn glucoheptonate.

Executive summary:

The data on manganese sulfate allows estimating corresponding EC50 and IC50 for manganese glucoheptonate providing that no toxicity is attributed to the sulfate or glucoheptonate ion, that the absorption of manganese from this manganese compounds is 100 % and all manganese became systemically available. 

The reported EC50(1h) corresponds to a value of 209.6 ± 18.3 mg/L and the IC50(9h) is 1633.5 mg/L for Mn glucoheptonate.

 

For details regarding the calculation path please see section “Any other information on results incl. tables”.

Description of key information

Spirostomum ambiguum: EC50(24h) 721.8 ± 347.7 mg/L, EC50(48h) 847.8 ± 515.7 mg/L, LC50(24h) 1151.2 ± 120.6 mg/L and LC50(48h) 1135.6 ± 151.7 mg/L, based on occurrence of different deformations resp. lethal response, corrected for Mn glucoheptonate.

Tetrahymena pyriformis: EC50(1h) 209.6 ± 18.3 mg/L and the IC50(9h) 1633.5 mg/L, based on metabolic activity resp. growth inhibition, corrected for Mn glucoheptonate.

Additional information

There are two studies available on other aquatic organisms, conducted with either manganese chloride or manganese sulfate.. Although no mandatory endpoint under REACH, these studies on protozoae can be used to support the conclusion drawn in IUCLID chapter 6.1.5 "Toxicity to aquatic plants and cyanobacteria".

Within the two available studies, the information gained from Spirostomum ambiguum are considered to be the more reliable ones, because the test duration was up to 48 h instead of 9 h, and resulted in a more sensitive response.

Since both studies were assessed to be reliable with restrictions, the results can be considered as trustworthy. Since Spirostomum ambiguum serves as an additional species to assess the possible hazard of the test item to the environment, the same criteria for classification or non-classification should apply as for algae and other aquatic plants.

Taking into account the retrieved results, i.e. EC50(24h) 721.8 ± 347.7 mg/L, EC50(48h) 847.8 ± 515.7 mg/L, LC50(24h) 1151.2 ± 120.6 mg/L and LC50(48h) 1135.6 ± 151.7 mg/L, based on occurrence of different deformations resp. lethal response , corrected for manganese glucoheptonate from the free cation, it can be assumed that the EC50 and LC50 values after 72 h are unlikely to be significantly lower.

This result is in congruence with the results obtained from the toxicity study in algae.

Table 1: Effect concentrations (EC), Lethal concentrations (LC) and inhibitory concentration (IC) 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	water media type	Reference
Spirostonum ambiguum	24h	EC50	721.8 ± 347.7	freshwater	Nalecz-Jawecki & Sawicki (1998)
Spirostonum ambiguum	48h	EC50	847.8 ± 515.7	freshwater	Nalecz-Jawecki & Sawicki (1998)
Spirostonum ambiguum	24h	LC50	1151.2 ± 120.6	freshwater	Nalecz-Jawecki & Sawicki (1998)
Spirostonum ambiguum	48h	LC50	1135.6 ± 151.7	freshwater	Nalecz-Jawecki & Sawicki (1998)
Tetrahymena pyriformis	1h	EC50	209.6 ± 18.3	freshwater	Bogaerts et al (1998)
Tetrahymena pyriformis	9h	IC50	1633.5	freshwater	Bogaerts et al (1998)