Reaction products of sodium glucoheptonate with manganese sulfate and sodium hydroxide

Endpoint summary

Description of key information

Acute oral toxicity

To address the endpoint acute toxicity (oral), read-across on gluconates and derivatives and manganese compounds was performed within the frame of a weight-of-evidence approach.The underlying hypothesis for the read-across is that glucoheptonates and gluconates, structurally similar sugar-like carbohydrate metal-complexes, share the same metabolism pathways in mammals (they are oxidized by pentose phosphate pathway) and that their possible toxicity is a function of the metal cation rather than of the gluconate or glucoheptonate anion. Therefore, data on manganese sulfate, manganese chloride, manganese acetate and gluconates and derivatives were taken into account to assess the acute toxicity of manganese glucoheptonate.

Manganese compounds

The effect concentrations of manganese compounds were converted to the target substance manganese glucoheptonate under consideration of the molecular weight and the purity.

In an acute oral toxicity study similar to OECD Guideline 401 (Smyth et al., 1969), groups of non-fasted, 4 -5 weeks old Carworth-Wistar male rats (five rats / group) were given a single oral dose of Manganese acetate in water (0.2 g/ml) at doses arranged in a logarithmic series differing by a factor of two and were observed for 14 days. This study was evaluated with Klimisch 2 (reliable with restrictions). The oral LD50 in males was determined to be 3.73 g/kg bw. This corresponds to a LD50 of 6503.7 mg/kg bw for manganese glucoheptonate.

The toxicity of manganese chloride was determined in animals of five different age groups (2, 3, 6, 20, and 54 weeks) (Kolial et al., 1978). Manganese chloride was administered by stomach tube in a volume of 1 ml/200 g of body weight. Six dose levels were used in each age group. Each dose level was tested on six animals. This study was evaluated with Klimisch 2 (reliable with restrictions). The LD50 value of MnCl2 on female rats after oral application (by stomach tube) converted to manganese glucoheptonate is 6219 and 3088 mg/kg bw for 6 and 18 week-old rats, respectively. According to OECD guidelines on acute toxicity testing (OECD TG 420, 423 and 425), rats aged 8 to 12 weeks are recommended. Therefore, data of 6 and 18 week-old rats are taken into account. As a worst-case value 3088 mg/kg bw is selected here for hazard assessment.

In an acute oral toxicity study (Holbrook et al., 1975), groups of 4-5 weeks old male Sprague-Dawley rats were given a single oral dose of Manganese chloride and were observed for 14 days. This study was evaluated with Klimisch 2 (reliable with restrictions). The LD50 for manganese chloride tetrahydrate is reported to be 7.5 mmol/kg bw which corresponds to 1484.33 mg/kg bw. The corrected LD50 value for manganese glucoheptonate is 3205.1 mg/kg bw.

In an acute oral toxicity study (Singh and Junnarkar, 1991), groups of male and female Wistar albino rats and male Swiss albino mice (five animals / dose) were given a single oral dose by gavage of Manganese chloride and Manganese sulphate and were observed for 14 days. This study was evaluated with Klimisch 2 (reliable with restrictions). The LD50 for manganese sulfate is reported to be 2330 and 2150 mg/kg bw for male mice and male/female rats, respectively. Those values correspond to a LD50 of 6594.1 mg/kg bw for male mice and to a LD50 of 6084.7 mg/kg bw for male/female rats for manganese glucoheptonate. The LD50 for manganese chloride is reported to be 1330 and 1470 mg/kg bw for male mice and male/female rats, respectively. Those values correspond to a LD50 of 4516.6 mg/kg bw for male mice and to a LD50 of 4992 mg/kg bw for male/female rats for manganese glucoheptonate.

Gluconates and derivatives

Data on acute oral toxicity for sodium gluconate in rat (doses: 500, 1000, 2000 mg/kg) and dog (doses: 1000 and 2000 mg/kg) fed by gavage showed no death at any dose, hence the minimum lethal dose was estimated > 2000 mg/kg for both species (SIDS, 2004).

Rats were fed by gavage doses of 3000, 3600, 4320, 5190, 6210 mg/kg bw (30% (w/v) aqueous solution) of potassium gluconate and were observed for signs of toxicity during a 14-day period. One animal died in the 5190 mg/kg bw group and four animals in the 6210 mg/kg bw group. Deaths occurred between 5 and 21 hours after treatment. Survivors recovered gradually. The LD₅₀was calculated (according to the method of Weil) to be 6060 mg/kg bw. However, the effects that were observed occurred at doses that exceed the accepted limit dose of 5000 mg/kg bw and the LD₅₀may be related to high dosing (SIDS, 2004).

The World Health Organisation evaluated gluconic acid and its derivatives (WHO, 1996, 1999). Consideration of glucono-delta-lactone and gluconic acid is based mainly on the metabolic evidence that these compounds are intermediates in a normal pathway of glucose metabolism in mammalian species. There is also considerable experience with the comparatively low toxicity of gluconate to man and animals. Glucono-delta-lactone and gluconic acid are not toxic to animals and humans when given at very high dose levels (> 2000 mg/kg bw).

Acute toxicity by inhalation

To address the endpoint acute toxicity by inhalation, read-across from manganese compounds was performed within the frame of a weight-of-evidence approach. The underlying hypothesis for the read-across is that glucoheptonates and gluconates, structurally similar sugar-like carbohydrate metal-complexes, share the same metabolism pathways in mammals (they are oxidized by pentose phosphate pathway) and that their possible toxicity is a function of the metal cation rather than of the gluconate or glucoheptonate anion. Therefore, primarily data on manganese compounds (for soluble manganese compounds: manganese chloride, and for insoluble manganese compounds: manganese dioxide) have been taken into account to assess the acute inhalation toxicity of manganese glucoheptonate.

There are numerous study results reported on effects by inhalation caused by manganese compounds. However, no conclusive studies have been located that show inhalation exposure of humans or animals to manganese inorganic and organic compounds resulting in mortality (ATSDR, 2012). The target systems of manganese toxicity are the central nervous system and the respiratory system. There is evidence in animals and humans that adverse neurological and respiratory effects can result from exposure to different manganese compounds irrespective of their counter anion. Results from animal studies indicate that the solubility of inorganic manganese compounds can influence the bioavailability of manganese and subsequent delivery of manganese to critical toxicity targets such as the brain; however, the influence of manganese oxidation state on manganese toxicity is not currently well understood (ATSDR, 2012). Therefore, the data on both soluble manganese compounds and on less soluble / insoluble manganese compounds are considered valuable to assess an effect level of the target substance, it it was tested in an acute inhalation study.

Inhalation of particulate manganese compounds such as manganese dioxide or manganese tetraoxide leads to an inflammatory response in the lungs of animals which can lead to impaired lung function and this is accompanied by increased numbers of macrophages and leukocytes in the lung. Damage to lung tissue is usually not extensive, but may include local areas of edema. Symptoms and signs of lung irritation and injury may include cough, bronchitis, pneumonitis, and minor reductions in lung function. However, an inflammatory response of this type is not unique to manganese-containing particles, but is characteristic of nearly all inhalable particulate matter (EPA 1985d, cited in ATSDR, 2012). This suggests that it is not the manganese per se that causes the response, but more likely the particulate matter itself. On the other hand, since neurotoxicity effects were observed after exposure to manganese compounds, one can attribute these effects solely to manganese. Therefore, every piece of evidence on effects caused by inhalation of manganese compounds is considered important to estimate a reliable LC50 value or an effect level for sub-lethal effects for the target substance to be able to conclude on its hazard level.

An attempt was undertaken to estimate a LC50 based on LD50 value known for manganese. The lowest LD50 of 850 mg/kg bw for manganese chloride established for 18 -week old rats (Kolial, 1978) is used to estimate a corresponding LC50 value. The old rats were the most sensitive to the manganese chloride. Since MnGHA contains only 11% of particles that are slightly smaller than 100 µm, no respirable fraction exists in case of dust formation. Thus, the microgranulated product would form only inhalable fraction that would be deposited in the upper airways and can subsequently be swallowed. Thus, the dose absorbed orally and converted to a corresponding concentration does provide an estimate of an effect level needed to produce the same toxicity effects in animals if they were treated by inhalation. Therefore, by using the most relevant LD50 value for the oral route of exposure, a surrogate LC50 value is estimated. Even though route-to-route extrapolation includes high uncertainties, such an estimation could provide a range of effect level if the target substance was tested in an acute inhalation study. The corresponding LC50 value for manganese glucoheptonate is calculated 16082 mg/m³ for 18 week-old rats.

A LC50 for MnGHA was interpolated from NOAEC in mouse established for manganese chloride (Bredow et al., 2007). MnCl2 was administered to mice by inhalation at concentration of 2 mg Mn/m³. No histopathological changes in lungs were observed. There is no information on clinical signs in treated animals. ATSDR (2012) reported this value as NOAEC. Therefore, it is assumed that no mortalities and other adverse health effects were observed. Using a large assessment factor of 100 that is proposed by ECHA guidance to derive a DNEL for acute effects based on LC50 data, a surrogate LC50 of 200 mg/m³ for Manganese was derived. Subsequently, using a modified Haber's law, the concentration was further corrected for exposure time: the longer exposure time of 6 hours was interpolated to the shorther exposure time of 4 hours. Finally, the corrected LC50 for Manganese was converted in a corresponding LC50 for the target substance MnGHA. A LC50 of 1882 mg MnGHA/m³ is estimated for pulmonary effects in mouse.

The LC50 value of MnO2 reported in a short version of SIDS report (2007) was 1500 mg/m³ for rats. Converting this value to manganese glucoheptonate a LC50 would correspond to 7823 mg/m³ for 4 -h exposure time.

In another study, a LOAEC of 43 mg Mn/m³ and a NOAEC of 138 mg Mn/m³ are reported for respiratory and hematological effects in rats inhaled Manganese dioxide 6h/day during 10 days (Shiotsuka, 1984). Since respiratory effects, which served as basis for setting LOAEC, were assigned as "serios" health effects by ATSDR (2012), this study result has been taken into account to estimate a corresponding effect level for the target substance MnGHA.

A LC50 for MnGHA was interpolated from LOAEC in rats established for manganese dioxide. MnO2 was administered to rats by inhalation at concentration of 43 mg Mn/m³. Pneumonitis and increased lung weights were observed in treated animals. There is no information on clinical signs in treated animals. ATSDR (2012) reported this value as a LOAEC. Therefore, it is assumed that no mortalities and other adverse health effects were observed. Using a large assessment factor of 10 for dose response, a surrogate LC50 of 430 mg/m³ for Manganese was derived. Subsequently, using a modified Haber's law, the concentration was further corrected for exposure time: the longer exposure time of 6 hours was interpolated to the shorther exposure time of 4 hours. Finally, the corrected LC50 for Manganese was converted in a corresponding LC50 for the target substance MnGHA. A surrogate LC50 of 4064 mg MnGHA/m³ has been estimated for respiratory effects in rats.

Conclusion

Based on the available studies of the source substances, manganese glucoheptonate is considered not to be acute toxic. An oral LD50 value of 3088 mg/kg bw is selected here for hazard assessment as being the most reliable dose descriptor. This value was calculated from a LD50 derived in a study with MnCl2 on female rats after oral application (by stomach tube) (Kolial et al., 1978). For acute toxicity effects by inhalation, an estimated LC50 value of 16082 mg/m³ based on LD50 of 850 mg/kg bw, which was established for Manganese chloride, is selected for hazard assessment. Since only 11 % of the particles of the target substance MnGHA have a size below 100 µm, with no particles having a size below 70 µm, no respirable fraction exists, thus the LC50 values for the MnO2 and MnCl2 (both molecules with particles well within respirable fraction) are not suitable for the estimation of a corresponding LC50 value, as those overestimate the potential hazard of MnGHA by inhalation. Therefore, the oral LD50 is considered as the most relaible starting point for calculation of the corresponding LC50 value.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable well documented peer-reviewed reports.

Qualifier:

no guideline available

Principles of method if other than guideline:

Summary of acute toxicity data in animals.

GLP compliance:

not specified

Test type:

other: Summary of acute toxicity data in animals.

Species:

other: rats and dogs

Strain:

other: rats: Sprague Dawley; dogs: no data

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

VEHICLE
- Concentration in vehicle:
- Amount of vehicle (if gavage):
- Justification for choice of vehicle:
- Lot/batch no. (if required):
- Purity:

MAXIMUM DOSE VOLUME APPLIED:

DOSAGE PREPARATION (if unusual):

CLASS METHOD (if applicable)
- Rationale for the selection of the starting dose:

Doses:

Rats: 500, 1000, 2000 mg/kg bw (Mochizuki, 1995) and 3000, 3600, 4320, 5190, 6210 mg/kg bw (TNO, 1978);
Dogs: 1000 and 2000 mg/kg bw (Okamoto, 1995).

No. of animals per sex per dose:

Rats: 5 sex/dose;
Dogs: no data

Details on study design:

Rats:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: on days 1, 2, 3, 7, 10, and 14
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, and gross pathological changes in brain, pituitary, thyroid, salivary gland, thymus, heart, lung, liver, spleen, kidney, adrenals, stomach, small and large intestine, pancreas, gonads, urinary bladder, and lymph nodes.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks:

sodium gluconate

Remarks on result:

other: for rats and dogs (Mochizuki, 1995; Okamoto, 1995).

Sex:

not specified

Dose descriptor:

LD50

Effect level:

6 060 mg/kg bw

Based on:

test mat.

Remarks:

potassium gluconate

Remarks on result:

other: for rats (TNO, 1978)

Mortality:

No mortality was observed (Mochizuki, 1995; Okamoto, 1995). One animal died in the 5190 mg/kg bw group and four animals in the 6210 mg/kg bw group. Deaths occurred between 5 and 21 hours after treatment. Survivors recovered gradually (TNO, 1978).

Clinical signs:

other: Soft faeces and diarrhoea, seen in one male and three females at 2000 mg/kg bw, were the only clinical effects observed 2-3 h after treatment (Mochizuki, 1995).

Gross pathology:

No gross abnormalities were observed at necropsy (Mochizuki, 1995).

Other findings:

The minimum lethal dose was > 2000 mg/kg bw, although a transient, initial laxative effect was observed in rats at doses > 1000 mg/kg bw (Mochizuki, 1995).

Data on acute oral toxicity for sodium gluconate in rat (Mochizuki, M, Bozo Research Center 1995) (doses: 500, 1000, 2000 mg/kg) and dog (Okamoto M., 1995) (doses: 1000 and 2000 mg/kg) fed by gavage showed no death at any dose, hence the minimum lethal dose was estimated > 2000 mg/kg for both species.

Rats were fed by gavage 3000, 3600, 4320, 5190, 6210 mg/kg bw (30% (w/v) aqueous solution) potassium gluconate and were observed for signs of toxicity during a 14-day period. One animal died in the 5190 mg/kg bw group and four animals in the 6210 mg/kg bw group. Deaths occurred between 5 and 21 hours after treatment. Survivors recovered gradually. The LD50 was calculated (according to the method of Weil) to be 6060 mg/kg bw. However, the effects that were observed occurred at doses that exceed the accepted limit dose of 5000 mg/kg bw and the LD₅₀ may be related to high dosing (TNO, 1978). No relevant oral toxicity data were found in the literature for the other substances of the category. Conclusion Studies with sodium gluconate in the rat and dog report LD₅₀ values > 2000 mg/kg bw for both species. A gavage study with potassium gluconate and rats reported an LD₅₀ of 6060 mg/kg bw.

Conclusions:

Oral LD50 > 2000 mg/kg bw was established for rats and dogs for gluconates.

Executive summary:

Data on acute oral toxicity for sodium gluconate in rat (doses: 500, 1000, 2000 mg/kg) and dog (doses: 1000 and 2000 mg/kg) fed by gavage showed no death at any dose, hence the minimum lethal dose was estimated > 2000 mg/kg for both species.

Rats were fed by gavage 3000, 3600, 4320, 5190, 6210 mg/kg bw (30% (w/v) aqueous solution) potassium gluconate and were observed for signs of toxicity during a 14-day period. One animal died in the 5190 mg/kg bw group and four animals in the 6210 mg/kg bw group. Deaths occurred between 5 and 21 hours after treatment. Survivors recovered gradually. The LD50 was calculated (according to the method of Weil) to be 6060 mg/kg bw. However, the effects that were observed occurred at doses that exceed the accepted limit dose of 5000 mg/kg bw and the LD50 may be related to high dosing (TNO, 1978). No relevant oral toxicity data were found in the literature for the other substances of the category. In conclusion, the studies with sodium gluconate in the rat and dog report LD50 values > 2000 mg/kg bw for both species. A gavage study with potassium gluconate and rats reported an LD50 of 6060 mg/kg bw.

Reference 2

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable well documented data originating from peer-reviewed source.

Qualifier:

no guideline followed

Principles of method if other than guideline:

WHO provides summary of acute oral toxicity data on glucono-delta-lactone and gluconic acid in animals and humans.

GLP compliance:

no

Test type:

other: summary of acute data in animals and humans

Species:

other: humans, rats, mice, rabbits and hamsters

Strain:

not specified

Sex:

not specified

Route of administration:

oral: unspecified

Vehicle:

not specified

Doses:

Humans: 5 g (84 mg/kg bw), 10 g (167 mg/kg bw) and 30 g (500 mg/kg bw) per person;
Other species: no data

No. of animals per sex per dose:

no data

Sex:

not specified

Dose descriptor:

other: Estimate of acceptable daily intakes for man

Effect level:

0 - 15 mg/kg bw

Based on:

test mat.

Remarks on result:

other: unconditional acceptance (established at the tenth meeting)

Sex:

not specified

Dose descriptor:

other: Estimate of acceptable daily intakes for man

Effect level:

15 - 50 mg/kg bw

Based on:

test mat.

Remarks on result:

other: conditional acceptance (established at the tenth meeting)

Sex:

not specified

Dose descriptor:

other: Acceptable Daily Intake (ADI) for man

Effect level:

other: not specified

Based on:

test mat.

Remarks on result:

other: At its thirtieth meeting, the Committee changed the ADI for glucono-delta-lactone to an ADI 'not specified'

Sex:

female

Dose descriptor:

LDLo

Effect level:

> 10 000 other: ppm in feed

Based on:

test mat.

Remarks:

Glucono-delta-lactone

Remarks on result:

other: in rats

Sex:

not specified

Dose descriptor:

LD50

Effect level:

5 940 mg/kg bw

Based on:

test mat.

Remarks:

Glucono-delta-lactone

Remarks on result:

other: in rats

Sex:

not specified

Dose descriptor:

LD50

Effect level:

6 800 mg/kg bw

Based on:

test mat.

Remarks:

Glucono-delta-lactone

Remarks on result:

other: in mouse

Sex:

not specified

Dose descriptor:

LD50

Effect level:

7 850 mg/kg bw

Based on:

test mat.

Remarks:

Glucono-delta-lactone

Remarks on result:

other: in rabbits

Sex:

not specified

Dose descriptor:

LD50

Effect level:

5 600 mg/kg bw

Based on:

test mat.

Remarks:

Glucono-delta-lactone

Remarks on result:

other: hamster

Humans

When three men were given 10 g (167 mg/kg) of glucono-delta-lactone orally as a 10 % solution, the amounts recovered in the urine in 7 hours represented 7.7-15 % of the dose. No pathological urine constituents were noted. When 5 g (84 mg/kg) was given orally, none was recovered in the urine. The largest dose given to man was 30 g (500 mg/kg) (Chenoweth et al., 1941).

The administration for 3-6 days of large oral doses (5-10 g/day) of gluconic acid to five normal humans did not produce any renal changes, as by the absence of blood, protein, casts and sugar in the urine (Chenoweth et al., 1941).

Rat

Groups of 20 male and 20 female rats were fed gluconic acid (as glucono-delta-lactone) for 26 weeks at levels of 0 and 10 000 ppm in the diet without ill effects or demonstrable changes in the main organs on microscopic examination (Harper & Gaunt, 1962).

Conclusions:

Glucono-delta-lactone and gluconic acid are not toxic to animals and humans when given at very high dose levels.

Executive summary:

Consideration of glucono-delta-lactone and gluconic acid is based mainly on the metabolic evidence that these compounds are intermediates in a normal pathway of glucose metabolism in mammalian species. There is also considerable experience with the comparatively low toxicity of gluconate to man and animals.

Glucono-delta-lactone and gluconic acid are not toxic to animals and humans when given at very high dose levels (> 2000 mg/kg bw).

Reference 3

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

no guideline followed

Principles of method if other than guideline:

Manganese chloride was applied orally via stomach tube to rats, the animals were observed through a 14-day observation period, LD50 values were calculated.

GLP compliance:

not specified

Test type:

other: unknown

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 4-5 weeks
- Weight at study initiation: 100-110 g
- Acclimation period: 1-1,5 weeks
No further details on test animals and environmental were given

Route of administration:

oral: gavage

Vehicle:

not specified

Details on oral exposure:

Administration orally via stomach tube
No further details on oral exposure were given

Doses:

unknown

No. of animals per sex per dose:

unknown

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days
No further details on study design were given

Statistics:

Calculation of LD50 values according to Litchfield and Wilcoxon with given ranges of 95% confidence limits

Sex:

male

Dose descriptor:

LD50

Effect level:

7.5 other: mmole/kg bw

Based on:

test mat.

95% CL:

7 - 8.1

Sex:

male

Dose descriptor:

LD50

Effect level:

1 484.33 mg/kg bw

Based on:

test mat.

Remarks on result:

other: converted to mg/kg bw

Other findings:

In a comparable lethal dose experiment, rats were treated orally with a dose of MnCl, * 4H20 equivalent to 100%o of the oral LD50 value, and the tissues were analyzed in surviving rats at the end of the 14-day observation period. The results are shown in table 1.

Table 1: Mn concentration in rat tissues following the oral administration of a single large dose of MnCI2.4H20.

	Controls	MnCl2-4H20
Dose of Mn, mg Mn/kg Tissue concentration of Mn,µgMn/g wet weight of tissue*	—	416
Liver	1.60±0.87	1.9(1.3-2.5)
Kidney	0.75±0.50	1.3(1.0-1.5)
Spleen	1.46±1.99	1.3 (1.1-1.5)
Heart	0.55±0.35	0.7
Testes	0.44±0.35	0.5 (0.4-0.5)
Brain	0.3	0.03
Blood	0.86±0.44	0.4 (0.2-0.6)

* Control values are from rats treated orally with NaCl, and rats on diet experiments for approximately 8 or 30 days. Means ± standard deviations are given for 6-7 samples of spleen, heart and blood and for 13-18 samples of liver, kidney and testes from control rats; ranges are given in parentheses where two values are available from Mn-treated rats.

Interpretation of results:

sligthly toxic

Conclusions:

In the present study, acute toxicity of MnCl2 in male rats, the LD50 value was determined as 7.5 mmole/kg bw which is equal to 1484.33 mg/kg bw MnCl2*4H2O.

Executive summary:

In an acute oral toxicity study, groups of 4-5 weeks old male Sprague-Dawley rats were given a single oral dose of Manganese chloride and were observed for 14 days. The oral LD50 in males was determined to be 7.5 mmole/kg bw which corresponds to a value of 1484.33 mg/kg bw MnCL2 * 4H2O.

Reference 4

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

no guideline followed

Principles of method if other than guideline:

Rats and mice (five animals/group) were administred the test substance in de-ionized water via oral, intra-peritoneal and intra-venous route; LD50 values were determined.

GLP compliance:

not specified

Test type:

other: no data

Species:

other: rat, mouse

Strain:

other: Wistar strain of albino rats, Swiss strain of male albino mice

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 20-22 g (mice), 100-125 g (rat)
- Fasting period before study: no data
- Housing: polycarbonate cages
- Diet (e.g. ad libitum): Gold Mohur Hind Lever diet ad libitum
- Water (e.g. ad libitum): ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24 ± 0.5
- Photoperiod (hrs dark / hrs light): 12 h / 12 h

Route of administration:

oral: gavage

Vehicle:

water

No. of animals per sex per dose:

five

Control animals:

yes

Statistics:

LD50 values and fiducial limits were calculated using the method of Horn (Horn, H.J., Simplified LD50 (or EC50) calculations, Biometrics 1956; 12; 311-25)

Sex:

male

Dose descriptor:

other: LD50, mice

Effect level:

2 330 mg/kg bw

Based on:

test mat.

Remarks:

MnSO4

Sex:

male

Dose descriptor:

other: LD50, mice

Effect level:

1 330 mg/kg bw

Based on:

test mat.

Remarks:

MnCl2

Sex:

male/female

Dose descriptor:

other: LD50, rats

Effect level:

2 150 mg/kg bw

Based on:

test mat.

Remarks:

MnSO4

Sex:

male/female

Dose descriptor:

other: LD50, rats

Effect level:

1 470 mg/kg bw

Based on:

test mat.

Remarks:

MnCl2

Conclusions:

The LD50 values are reported to be 2330 mg/kg bw (MnSO4, mice), 1330 mg/kg bw (MnCl2, mice), 2150 mg/kg bw (MnSO4, rats) and 1470 mg/kg bw (MnCl2, rats).

Executive summary:

In an acute oral toxicity study, groups of male and female Wistar albino rats and male Swiss albino mice (five animals / dose) were given a single oral dose by gavage of Manganese chloride and Manganese sulphate and were observed for 14 days. The oral LD50 in male Swiss albino mice was determined to be 2330 mg/kg bw MnSO4 and 1330 mg/kg bw MnCl2, in male and female Wistar rats 2150 mg/kg bw MnSO4 and 1470 mg/kg bw MnCl2.

Reference 5

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP study similar to guideline with deviations, documentation on raw data missing. However, the given data indicate that the study was well-performed.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

yes

Remarks:

animals are non-fasted, certain documentation is lacking

GLP compliance:

no

Test type:

acute toxic class method

Limit test:

no

Species:

rat

Strain:

other: Carworth-Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: reared in in-house colony, Mellon Institute of Industrial Research, Pittsburgh, Pennsylvania
- Age at study initiation: 4 -5 weeks
- Weight at study initiation: 90 - 120 g
- Fasting period before study: no
- Housing: unknown
- Diet (e.g. ad libitum): Rockland rat diet

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

Gavage of solution of a concentration of 0.2 g/ml Mn(OOCH3)2*4H2O

Doses:

Arranged in a logarithmic series differing by a factor of two

No. of animals per sex per dose:

5

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: no data

Statistics:

The most probalbe LD50 value and its fiducial range are estimated b ythe method of Thompson (Thompson, W.R.: Use of moving averages and interpolation to estimate median effective dose. Bacteriol. Rev. 11:115 (June 1947)) using the tables of Weil (Weil, C.S.: Tables for convenient calculation of median-effective dose (LD50 or EC50) and instructions on their use. Biometrics 8:249 (Sept. 1952)).

Preliminary study:

no data

Sex:

male

Dose descriptor:

LD50

Effect level:

ca. 3 730 mg/kg bw

Based on:

test mat.

Remarks on result:

other: Single oral LD50 vary from 2680-5210 mg/kg bw, expressed as Manganese Acetate Tetrahydrate

Mortality:

no data

Clinical signs:

other: no data

Gross pathology:

no data

Other findings:

no data

Interpretation of results:

relatively harmless

Conclusions:

Although there are some deficiencies in documentation, the given data indicate that the study was well-performed similar to OECD guideline 401. Therefore, the results can be considered as reliable. The LD50 value of manganese acetate in rats was 3.73 g/kg bw.

Executive summary:

In an acute oral toxicity study, groups of non-fasted, 4 -5 weeks old Carworth-Wistar male rats (five rats / group) were given a single oral dose of Manganous acetate in water (0.2 g/ml) at doses arranged in a logarithmic series differing by a factor of two and were observed for 14 days. The oral LD50 in males was determined to be 3.73 g/kg bw .

Reference 6

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1978

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

no guideline followed

Principles of method if other than guideline:

The toxicity of manganese chloride was determined in animals of five different age groups (2, 3, 6, 20, and 54 weeks). Manganese chlorides were administered by stomach tube in a volume of 1 ml/200 g of body weight. Six dose levels were used in each age group. Each dose level was tested on six animals. The LD50 values and the 95% confidence limits were calculated by the method of moving averages 8 days after a single oral administration.

GLP compliance:

no

Test type:

fixed dose procedure

Limit test:

no

Specific details on test material used for the study:

no details given

Species:

rat

Strain:

other: Albino rats

Sex:

female

Details on test animals or test system and environmental conditions:

During the experiment, suckling rats aged one and two weeks were kept in a litter of six together with their mothers. Weanling rats and older rats were fed a stock laboratory diet (1.2% Ca and 0.8% P). Cow's milk was used in experiments in which rats received a "milk diet" ad libitum.

Route of administration:

oral: gavage

Vehicle:

not specified

Details on oral exposure:

Manganese chloride was administered by stomach tube.

Doses:

1 ml/200 g of body weight, 6 dose levels

No. of animals per sex per dose:

6 animals per dose level

Control animals:

not specified

Details on study design:

no details given

Statistics:

The LD50 values and the 95% confidence limits were calculated by the method of moving averages 8 days after a single oral administration.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

804 mg/kg bw

Based on:

test mat.

95% CL:

>= 43 - <= 51

Remarks on result:

other: 2 weeks old sucklings

Sex:

female

Dose descriptor:

LD50

Effect level:

1 860 mg/kg bw

Based on:

test mat.

95% CL:

>= 1 655 - <= 2 009

Remarks on result:

other: 3 weeks old rats

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

1 712 mg/kg bw

Based on:

test mat.

95% CL:

>= 1 553 - <= 1 887

Remarks on result:

other: 6 weeks old rats

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

850 mg/kg bw

Based on:

test mat.

95% CL:

>= 775 - <= 957

Remarks on result:

other: 18 weeks old rats

Sex:

female

Dose descriptor:

LD50

Effect level:

619 mg/kg bw

Based on:

test mat.

95% CL:

>= 564 - <= 702

Remarks on result:

other: 54 weeks old rats

The highest oral toxicity was found in the youngest group of rats (two week-old sucklings) as indicated by the lowest LD50 values for manganese. In three and six week-old animals a sharp decrease in toxicity was noted and in comparison to sucklings LD50 values increased by a factor of 2. In adult rats the toxicity increased again and reached in the oldest animals values which were similar to sucklings. The increase in the toxicity of metals in sucklings was not as high as expected on the basis of the very high intestinal absorption at this age. The lower sensitivity to toxic metals might result from a different binding of metals to ligands and a lower level of "free metal" in sucklings. Older rats might be more susceptible to metal toxicity because of a general decrease in adaptive responsiveness which is characteristic of the process of aging.

Conclusions:

The LD50 value of MnCl2 on female rats after oral application (by stomach tube) was 1712 and 850 mg/kg bw for 6 and 18 week-old rats, respectively.

Executive summary:

The toxicity of manganese chloride was determined in animals of five different age groups (2, 3, 6, 20, and 54 weeks). Manganese chloride was administered by stomach tube in a volume of 1 ml/200 g of body weight. Six dose levels were used in each age group. Each dose level was tested on six animals. The LD50 values for 6 and 18 week-old rats, the most relevant age-groups for hazard assessment, was 1712 and 850 mg/kg bw, respectively.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

3 088 mg/kg bw

Quality of whole database:

Four studies assessed with Klimisch 2 and data from peer-reviewed reports are available to cover the endpoint "Acute Toxicity: oral", hence, the available information meets fully the tonnage-driven data requirements of REACH. All available studies revealed rather equivalent results (above the boundary value of 2000 mg/kg bw).

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: inhalation

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 with metals is driven by the supplied metal cation that can affect the mineral balance of the body, while no or very little toxicity is attributed to the organic part of the molecule - glucoheptonate moiety - up to considerable amounts. Manganese glucoheptonate is expected to dissociate from its complex, releasing metal cation - manganese - at physiological pHs. So, glucoheptonate anion is fully protonated at low pH values and is not able to participate in complexation of other metal cations: the stability constant of manganese glucoheptonate is low, the chelate is a weak complex at pH range 4-9 (Alekseev et al., 1998; please refer to the read-across statement). Therefore, the released equimolar amount of manganese from manganese glucoheptonate is expected to determine its toxicity in mammals. In this regard, the toxicity of manganese originated from a dissociating manganese compound (irrespectively organic or inorganic) could provide valuable information on the toxicity of manganese glucoheptonate. Therefore, data on elemental manganese, organic (manganese gluconate) or inorganic (especially soluble manganese salts, because manganese glucoheptonate is also a soluble manganese compound) is presented here as source of data for the target substance manganese glucoheptonate to address the toxicity of the metal cation.
Particularly for inhalation route of exposure, there are no studies located that show inhalation exposure of humans to manganese resulting in death. Since there is evidence in animals and humans that the main adverse neurological and respiratory effects can result from exposure to different manganese compounds, the data on Manganese dioxide - a less soluble maganese compound - is considered to be valuable for the assessment of acute hazard by inhalation of the target substance Manganese glucoheptonate. Moreover, since the influence of manganese oxidation state on manganese toxicity is not currently well understood, LC50 value for Manganese dioxide could help to define a range of effect levels in which Manganese glucoheptonate would exert its toxicity by inhalation route of exposure.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Information on purity of the registered substance is provided in the target record under "Test material" as confidential. The calculation of a LC50 value for manganese glucoheptonate is based on 66 % content of manganese glucoheptonate in the registered product. Another component is Na2SO4. Sodium is a macroelement occuring in surface waters and in living organisms in considerable amounts. Sulfur species are also found in living organisms. Thus, these cations and anions are considered not to impact the acute toxicity of manganese to mammals. There is no information on the purity of the source substance manganese dioxide. Only a brief result is reported in ATSDR. A purity of 100 % was therefore assumed.

3. ANALOGUE APPROACH JUSTIFICATION
As announced in the hypothesis for the read-across, manganese glucoheptonate is expected to dissociate in the moisture of lung's fluid (pH 7), releasing manganese. In contrast, manganese dioxide is described as practically insoluble compound in water. On the other hand, workers exposed to manganese dioxide fumes or dusts had symptoms associated with neurological action of manganese. Thus, manganese liberated from different manganese compounds drives the toxicity, irrespecively on counter anion. Therefore, data on the toxicity of manganese dioxide is presented here in order to evaluate manganese toxicity and to assess the toxicity of the target substance. The amount of manganese released from manganese glucoheptonate and from manganese oxide may be different because the molecular masses of these compounds are different. As a result, different amounts of manganese are released from the same amounts (by weight) of manganese dioxide and manganese glucoheptonate. However, using hazard values for elemental manganese, a corresponding hazard value can be calculated for manganese glucoheptonate. The validity of the read-across from inorganic manganese compounds could be affected by different absorption rates (as a result of diffferent solubilities as well) of structurally dissimilar manganese compounds in the lungs. However, in light of weight-of-evidence approach, every piece of data on manganese toxicity aids to create a rough estimation of the toxicity of the target substance.

4. DATA MATRIX
please refer to the data matrix attached in section 13.

Reason / purpose for cross-reference:

read-across source

Test type:

other:

Sex:

not specified

Dose descriptor:

LC50

Remarks:

estimation for MnGHA

Effect level:

4 064 mg/m³ air

Based on:

test mat. (total fraction)

Exp. duration:

4 h

Remarks on result:

other: estimated

Remarks:

(for respiratory effects). The effect is assigned as serious health effect.

Other findings:

Pneumonitis and increased lung weight were observed in treated animals.

A corresponding LC50 value is calculated for the target substance as follows:

LOAEC(Mn) in source substance is reported to be 43 mg Mn/m³

Source substance MnO2

To convert LOAEC to LC50, an assessment factor of 10 is considered appropriate for dose response. This AF covers sufficiently exposure duration (animals were exposed daily during 5 days, while acute inhalation exposure is 4 hours in one single day).

Thus, a very surrogate LC50 value for Mn would be 43 mg/m³ x 10 = 430 mg/m³.

The animals were exposed to manganese dioxide by inhalation during 6 hours/day, but exposure in an acute inhalation study should be 4 hours. Therefore, the obtained surrogate LC50 is corrected for time-scaling using the modified Haber's law (Gaylor, 2000):

In case of extrapolation from longer to shorter durations of exposure the formula is: (C³ x t) = (C')³ x t', giving C' = C x (t/t')E0.333. C' is the sought concentration. C' = 430 x (6 h/4h)^0.333 = 492 mg/m³

LC50 of target substance MnGHA

MW Mn in MnGHA = 109.8 g/mol

MW MnGHA = 598.28 g/mol

LC50 (MnGHA) in target = (LC50 (Mn) in source / 109.8) x 598.28

LC50 (Mn) in source = 492 mg/m³

LC50 (MnGHA) in target = (492 / 109.8) x 598.28 = 2682 mg/m³

Purity: 66 %

5163.3 / 0.66 = 4064 mg/m³

Since MnGHA contains only 11% of particles that are slightly smaller than 100 µm, no respirable fraction exists in case of dust formation. Thus, the microgranulated product would form only inhalable fraction that would be deposited in the upper airways and can subsequently be swallowed.

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

A surrogate LC50 of 4064 mg MnGHA/m³ has been estimated for respiratory effects in rats.

Executive summary:

Acute inhalation exposure to high concentrations of manganese dusts (manganese dioxide, manganese tetroxide) can cause an inflammatory response in the lung, which can lead to impaired lung function and this is accompanied by increased numbers of macrophages and leukocytes in the lung (ATSDR, 2012). A LOAEC of 43 mg Mn/m³ and a NOAEC of 138 mg Mn/m³ are reported for respiratory and hematological effects in rats inhaled 6h/day during 10 days by Manganese dioxide (Shiotsuka, 1984). Since respiratory effects, which served as basis for setting LOAEL, were assigned as "serios" health effects, this study result has been taken into account for the read-across to the target substance MnGHA.

A LC50 for MnGHA was interpolated from LOAEC in rats established for manganese dioxide. MnO2 was administered to rats by inhalation at concentration of 43 mg Mn/m³. Pneumonitis and increased lung weights were observed in treated animals. There is no information on clinical signs in treated animals. ATSDR (2012) reported this value as a LOAEC. Therefore, it is assumed that no mortalities and other adverse health effects were observed. Using a large assessment factor of 10 for dose response, a surrogate LC50 of 430 mg/m³ for Manganese was derived. Subsequently, using a modified Haber's law, the concentration was further corrected for exposure time: the longer exposure time of 6 hours was interpolated to the shorther exposure time of 4 hours. Finally, the corrected LC50 for Manganese was converted in a corresponding LC50 for the target substance MnGHA. A surrogate LC50 of 4064 mg MnGHA/m³ has been estimated for respiratory effects in rats.

Reference 2

Endpoint:

acute toxicity: inhalation

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 with metals is driven by the supplied metal cation that can affect the mineral balance of the body, while no or very little toxicity is attributed to the organic part of the molecule - glucoheptonate moiety - up to considerable amounts. Manganese glucoheptonate is expected to dissociate from its complex, releasing metal cation - manganese - at physiological pHs. So, glucoheptonate anion is fully protonated at low pH values and is not able to participate in complexation of other metal cations: the stability constant of manganese glucoheptonate is low, the chelate is a weak complex at pH range 4-9 (Alekseev et al., 1998; please refer to the read-across statement). Therefore, the released equimolar amount of manganese from manganese glucoheptonate is expected to determine its toxicity in mammals. In this regard, the toxicity of manganese originated from a dissociating manganese compound (irrespectively organic or inorganic) could provide valuable information on the toxicity of manganese glucoheptonate. Therefore, data on elemental manganese, organic (manganese gluconate) or inorganic (especially soluble manganese salts, because manganese glucoheptonate is also a soluble manganese compound) is presented here as source of data for the target substance manganese glucoheptonate to address the toxicity of the metal cation.
Particularly for inhalation route of exposure, there are no studies located that show inhalation exposure of humans to manganese resulting in death. Thus, the present study result with a clear NOAEC is taken to interpolate to a sub-lethal (LOAEC) and then to an exposure level near LC50. Even though such a calculation includes high uncertainties, an estimation could provide a range of effect level if the target substance was tested in an acutre inhalation study.


2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Information on purity of the registered substance is provided in the target record under "Test material" as confidential. The calculation of a LC50 value for manganese glucoheptonate is based on 66 % content of manganese glucoheptonate in the registered product. Another component is Na2SO4. Sodium is a macroelement occurring in surface waters and in living organisms in considerable amounts. Sulfur species are also found in living organisms. Thus, these cations and anions are considered not to impact the acute toxicity of manganese to mammals. There is no information on the purity of the source substance manganese chloride. A purity of 100 % was therefore assumed.

3. ANALOGUE APPROACH JUSTIFICATION
As announced in the hypothesis for the read-across, manganese glucoheptonate is expected to dissociate, especially in the acidic environments of stomach and in the moisture of lung's fluid (pH 7), releasing manganese. Manganese chloride is also a soluble dissociating compound. In the available public reports, Manganese chloride was reported not to induce adverse effects in animals and in humans occupationally exposed to its airborne form. Elevated levels of certain markers sufggestive of respiratory disease were however observed in animals treated by aerosols of manganese chloride. Thus, manganese liberated from different manganese compounds drives the toxicity, irrespecively on counter anion. Therefore, inhalative data on the toxicity of manganese chloride is presented here in order to evaluate manganese toxicity and to assess the toxicity of the target substance if it were tested in an acute inhalation study. The amount of manganese released from manganese glucoheptonate and from manganese chloride may be different because the molecular masses of these compounds are different. As a result, different amounts of manganese are released from the same amounts (by weight) of manganese chloride and manganese glucoheptonate. However, using hazard values for elemental manganese, a corresponding hazard value can be calculated for manganese glucoheptonate. The validity of the read-across from inorganic manganese compounds could be affected by different absorption rates (as a result of different solubilities as well) of structurally dissimilar manganese compounds in the lungs and in the stomach. However, in light of weight-of-evidence approach, every piece of data on manganese toxicity aids to create a rough estimation of the toxicity of the target substance.

4. DATA MATRIX
please refer to the data matrix attached in section 13.

Reason / purpose for cross-reference:

read-across source

Sex:

female

Dose descriptor:

LC50

Effect level:

>= 1 882 mg/m³ air

Based on:

test mat. (total fraction)

Exp. duration:

4 h

Remarks on result:

other: estimation for MnGHA

Effect of inhaled Mn(II) on mouse lungs

To determine if the in vitro effects could be observed in vivo, we investigated the effects of MnCl2-aerosol in adult mouse lungs after nose-only inhalation to an occupationally relevant concentration of 2 mg Mn/m3 air. Following a 6h/day exposure for 5 consecutive days, lung pathology remained unremarkable. Other than a minor increase in the number of alveolar macrophages and rare neutrophils in the peribronchiolar interstitium, no significant compound-associated lesions were found in the lungs of exposed animals.

A corresponding LC50 value is calculated for the target substance as follows:

NOAEC (Mn) in source substance is reported already as mg Mn/m³: 2 mg/m³

An average particle size of manganese chloride's aerosol inhaled by animals was 1.98 µm. These are clear respirable particles that easily reach alveoles. Since MnGHA contains only 11% of particles that are slightly smaller than 100 µm, no respirable fraction exists in case of dust formation. Thus, the microgranulated product would form only inhalable fraction that would be deposited in the upper airways and can subsequently be swallowed. In case of aerosol formation by usage of the target substance in a liquid form, respirable fraction can be generated as well. Considering that 100 % of the target substance MnGHA in form of respirable aerosol (a very worst-case) no correction for different fractions absorbed by different routes of exposure is considered nesessary.

To convert NOAEC to LOAEC an assessment factor of 10 is considered appropriate because no information on dose-response exists in this study. Additionally, according to ATSDR (2012), there are approximately ten-fold higher concentrations of manganese compounds reported that did not produce mortalities in animal studies. To convert LOAEC to LC50, an additional assessment factor of 10 is considered appropriate. This AF covers sufficiently exposure duration (animals were exposed daily during 5 days, while acute inhalation exposure is 4 hours in one single day).

Thus, using a very large assessment factor without scientific basis (similar to that proposed by ECHA guidance (Chapter R.8) to derive DNEL for acute effects from LC50 value, Appendix R.8 -8, Box 5), a very surrogate LC50 value for Mn would be 2 mg/m³ x 100 = 200 mg/m³.

The animals were exposed to manganese chloride by inhalation during 6 hours/day, but exposure in an acute inhalation study should be 4 hours. Therefore, the obtained surrogate LC50 is corrected for time-scaling using the modified Haber's law (Gaylor, 2000):

In case of extrapolation from longer to shorter durations of exposure the formula is: (C³ x t) = (C')³ x t', giving C' = C x (t/t')E0.333. C' is the sought concentration. C' = 200 x (6 h/4h)^0.333 = 228 mg/m³

LC50 of target substance MnGHA

MW Mn in MnGHA = 109.8 g/mol

MW MnGHA = 598.28 g/mol

LC50 (MnGHA) in target = (LC50 (Mn) in source / 109.8) x 598.28

LC50 (Mn) in source = 228 mg/m³

LC50 (MnGHA) in target = (228 / 109.8) x 598.28 = 1242 mg/m³

Purity: 66 %

1242 / 0.66 = 1882 mg/m³

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

A LC50 of 1882 mg MnGHA/m³ is estimated for pulmonary effects in mouse.

Executive summary:

A LC50 for MnGHA was interpolated from NOAEC in mouse established for manganese chloride. MnCl2 was administered to mice by inhalation at concentration of 2 mg Mn/m³. No histopathological changes in lungs were observed. There is no information on clinical signs in treated animals. ATSDR (2012) reported this value as NOAEC. Therefore, it is assumed that no mortalities and other adverse health effects were observed. Using a large assessment factor of 100 that is proposed by ECHA guidance to derive a DNEL for acute effects based on LC50 data, a surrogate LC50 of 200 mg/m³ for Manganese was derived. Subsequently, using a modified Haber's law, the concentration was further corrected for exposure time: the longer exposure time of 6 hours was interpolated to the shorther exposure time of 4 hours. Finally, the corrected LC50 for Manganese was converted in a corresponding LC50 for the target substance MnGHA. A LC50 of 1882 mg MnGHA/m³ is estimated for pulmonary effects in mouse.

Reference 3

Endpoint:

acute toxicity: inhalation

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 with metals is driven by the supplied metal cation that can affect the mineral balance of the body, while no or very little toxicity is attributed to the organic part of the molecule - glucoheptonate moiety - up to considerable amounts. Manganese glucoheptonate is expected to dissociate from its complex, releasing metal cation - manganese - at physiological pHs. So, glucoheptonate anion is fully protonated at low pH values and is not able to participate in complexation of other metal cations: the stability constant of manganese glucoheptonate is low, the chelate is a weak complex at pH range 4-9 (Alekseev et al., 1998; please refer to the read-across statement). Therefore, the released equimolar amount of manganese from manganese glucoheptonate is expected to determine its toxicity in mammals. In this regard, the toxicity of manganese originated from a dissociating manganese compound (irrespectively organic or inorganic) could provide valuable information on the toxicity of manganese glucoheptonate. Therefore, data on elemental manganese, organic (manganese gluconate) or inorganic (especially soluble manganese salts, because manganese glucoheptonate is also a soluble manganese compound) is presented here as source of data for the target substance manganese glucoheptonate to address the toxicity of the metal cation.
Particularly for inhalation route of exposure, there are no studies located that show inhalation exposure of humans to manganese resulting in death. Therefore, using LD50 value for oral route of exposure, a LC50 can theoretically be estimated. Even though route-to-route extrapolation includes high uncertainties, such an estimation could provide a range of effect level if the target substance was tested in an acute inhalation study.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Information on purity of the registered substance is provided in the target record under "Test material" as confidential. The calculation of a LC50 value for manganese glucoheptonate is based on 66 % content of manganese glucoheptonate in the registered product. Another component is Na2SO4. Sodium is a macroelement occurring in surface waters and in living organisms in considerable amounts. Sulfur species are also found in living organisms. Thus, these cations and anions are considered not to impact the acute toxicity of manganese to mammals. There is no information on the purity of the source substance manganese chloride. A purity of 100 % was therefore assumed.

3. ANALOGUE APPROACH JUSTIFICATION
As announced in the hypothesis for the read-across, manganese glucoheptonate is expected to dissociate, especially in the acidic environments of stomach and in the moisture of lung's fluid (pH 7), releasing manganese. Manganese chloride is also a soluble dissociating compound. In the available public reports, Manganese chloride was reported not to induce adverse effects in animals and in humans occupationally exposed to its airborne form. Elevated levels of certain markers sufggestive of respiratory disease were however observed in animals treated by aerosols of manganese chloride. Thus, manganese liberated from different manganese compounds drives the toxicity, irrespecively on counter anion. Therefore, oral data on the toxicity of manganese chloride is presented here in order to evaluate manganese toxicity and to assess the toxicity of the target substance if it was tested in an acute inhalation study. The amount of manganese released from manganese glucoheptonate and from manganese chloride may be different because the molecular masses of these compounds are different. As a result, different amounts of manganese are released from the same amounts (by weight) of manganese chloride and manganese glucoheptonate. However, using hazard values for elemental manganese, a corresponding hazard value can be calculated for manganese glucoheptonate. The validity of the read-across from inorganic manganese compounds could be affected by different absorption rates (as a result of different solubilities as well) of structurally dissimilar manganese compounds in the lungs and in the stomach. However, in light of weight-of-evidence approach, every piece of data on manganese toxicity aids to create a rough estimation of the toxicity of the target substance.

4. DATA MATRIX
please refer to the data matrix attached in section 13.

Reason / purpose for cross-reference:

read-across source

Species:

rat

Sex:

female

Dose descriptor:

other: estimated LC50 from LD50

Effect level:

16 082 mg/m³ air

Based on:

test mat. (total fraction)

Exp. duration:

4 h

Remarks on result:

other: estimation for MnGHA

A corresponding LC50 value is calculated for the target substance as follows:

18 week old rats

LD50(Mn) in source substance

Source substance MnCl2

MW (MnCl2) = 125.8 g/mol

MW (Mn) = 54.9 g/mol

Mn in MnCl2 = 54.9 / 125.8 = 0.44

LD50 (Mn) = LD50 (MnCl2) x 0.44 = 850 mg/kg bw x 0.44 = 374 mg/kg bw

Since MnGHA contains only 11% of particles that are slightly smaller than 100 µm, no respirable fraction exists in case of dust formation. Thus, the microgranulated product would form only inhalable fraction that would be deposited in the upper airways and can subsequently be swallowed. Thus, no correction for different fractions absorbed by different routes of exposure is considered nesessary. The dose absorbed orally and converted to a corresponding concentration would provide an estimate of an effect level needed to produce the same toxicity effects in animals if they were treated by inhalation.

Based on standard respiratory volume (sRV rat) of 0.8 L/min/kg bw (ECHA guidance, Chapter R.8), sRV of 0.192 m³/kg bw would be for 4 -hour exposure for rats. Thus, the formula of route-to-route extrapolation was used according to ECHA guidance (chapter R.8, Figure R.8 -3) to convert oral dose to a corresponding concentration considering absorption of 100 % for oral and inhalation routes of exposure (very worst-case):

Inhalatory LC50 = Oral LD50 /sRVrats = 374 mg/kg bw/0.192 m³/kg bw = 1948 mg/m³. This is the concentration of elemental manganese that would theoretically produce mortalities in rats if the animals were administered manganese chloride by inhalation.

LC50 of target substance MnGHA

MW Mn in MnGHA = 109.8 g/mol

MW MnGHA = 598.28 g/mol

LC50 (MnGHA) in target = (LC50 (Mn) in source / 109.8) x 598.28

LC50 (Mn) in source = 1948 mg/m³

LC50 (MnGHA) in target = (1948 / 109.8) x 598.28 = 10614 mg/m³

Purity: 66 %

10614 / 0.66 = 16082 mg/m³

Interpretation of results:

other: No C&L according to CLP is warranted based on this study result

Conclusions:

The LD50 value of MnCl2 on female rats after oral application (by stomach tube) converted to LC50 value for manganese glucoheptonate is 16082 mg/m³ for 18 week-old rats.

Executive summary:

The LD50 of 850 mg/kg bw for manganese chloride established for 18 -week old rats is used to estimate a corresponding LC50 value. The old rats were the most sensitive to the manganese chloride. Since MnGHA contains only 11% of particles that are slightly smaller than 100 µm, no respirable fraction exists in case of dust formation. Thus, the microgranulated product would form only inhalable fraction that would be deposited in the upper airways and can subsequently be swallowed. Thus, the dose absorbed orally and converted to a corresponding concentration would provide an estimate of an effect level needed to produce the same toxicity effects in animals if they were treated by inhalation. Therefore, using LD50 value for oral route of exposure, a surrogate LC50 value is estimated. Even though route-to-route extrapolation includes high uncertainties, such an estimation could provide a range of effect level if the target substance was tested in an acutre inhalation study. The corresponding LC50 value for manganese glucoheptonate is calculated 16082 mg/m³ for 18 week-old rats.

Reference 4

Endpoint:

acute toxicity: inhalation

Type of information:

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

Adequacy of study:

weight of evidence

Study period:

2007

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 with metals is driven by the supplied metal cation that can affect the mineral balance of the body, while no or very little toxicity is attributed to the organic part of the molecule - glucoheptonate moiety - up to considerable amounts. Manganese glucoheptonate is expected to dissociate from its complex, releasing metal cation - manganese - at physiological pHs. So, glucoheptonate anion is fully protonated at low pH values and is not able to participate in complexation of other metal cations: the stability constant of manganese glucoheptonate is low, the chelate is a weak complex at pH range 4-9 (Alekseev et al., 1998; please refer to the read-across statement). Therefore, the released equimolar amount of manganese from manganese glucoheptonate is expected to determine its toxicity in mammals. In this regard, the toxicity of manganese originated from a dissociating manganese compound (irrespectively organic or inorganic) could provide valuable information on the toxicity of manganese glucoheptonate. Therefore, data on elemental manganese, organic (manganese gluconate) or inorganic (especially soluble manganese salts, because manganese glucoheptonate is also a soluble manganese compound) is presented here as source of data for the target substance manganese glucoheptonate to address the toxicity of the metal cation.
Particularly for inhalation route of exposure, there are no studies located that show inhalation exposure of humans to manganese resulting in death. Since there is evidence in animals and humans that the main adverse neurological and respiratory effects can result from exposure to different manganese compounds, the data on Manganese dioxide - a less soluble maganese compound - is considered to be valuable for the assessment of acute hazard by inhalation of the target substance Manganese glucoheptonate. Moreover, since the influence of manganese oxidation state on manganese toxicity is not currently well understood, LC50 value for Manganese dioxide could help to define a range of effect levels in which Manganese glucoheptonate would exert its toxicity by inhalation route of exposure.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Information on purity of the registered substance is provided in the target record under "Test material" as confidential. The calculation of a LC50 value for manganese glucoheptonate is based on 66 % content of manganese glucoheptonate in the registered product. Another component is Na2SO4. Sodium is a macroelement occurring in surface waters and in living organisms in considerable amounts. Sulfur species are also found in living organisms. Thus, these cations and anions are considered not to impact the acute toxicity of manganese to mammals. There is no information on the purity of the source substance manganese dioxide. Only a brief result is reported in the short version of the SIDS report available on-line. A purity of 100 % was therefore assumed.

3. ANALOGUE APPROACH JUSTIFICATION
As announced in the hypothesis for the read-across, manganese glucoheptonate is expected to dissociate in the moisture of lung's fluid (pH 7), releasing manganese. In contrast, manganese dioxide is described as practically insoluble compound in water. On the other hand, workers exposed to manganese dioxide fumes or dusts had symptoms associated with neurological action of manganese. Thus, manganese liberated from different manganese compounds drives the toxicity, irrespecively on counter anion. Therefore, data on the toxicity of manganese dioxide is presented here in order to evaluate manganese toxicity and to assess the toxicity of the target substance. The amount of manganese released from manganese glucoheptonate and from manganese oxide may be different because the molecular masses of these compounds are different. As a result, different amounts of manganese are released from the same amounts (by weight) of manganese dioxide and manganese glucoheptonate. However, using hazard values for elemental manganese, a corresponding hazard value can be calculated for manganese glucoheptonate. The validity of the read-across from inorganic manganese compounds could be affected by different absorption rates (as a result of diffferent solubilities as well) of structurally dissimilar manganese compounds in the lungs. However, in light of weight-of-evidence approach, every piece of data on manganese toxicity aids to create a rough estimation of the toxicity of the target substance.

4. DATA MATRIX
please refer to the data matrix attached in section 13.

Reason / purpose for cross-reference:

read-across source

Duration of exposure:

>= 4 h

Sex:

not specified

Dose descriptor:

LC50

Remarks:

calculated for MnGHA

Effect level:

ca. 7 823 mg/m³ air

Based on:

test mat.

Exp. duration:

4 h

A corresponding LC50 value is calculated for the target substance as follows:

LC50(Mn) in source substance

Source substance MnO2

MW (MnO2) = 86.9 g/mol

MW (Mn) = 54.9 g/mol

Mn in MnO2 = 54.9 / 86.9 = 0.63

LC50 (Mn) = LC50 (MnO2) x 0.63 = 1500 mg/m³ x 0.63 = 947.6 mg/m³

LC50 of target substance MnGHA

MW Mn in MnGHA = 109.8 g/mol

MW MnGHA = 598.28 g/mol

LC50 (MnGHA) in target = (LC50 (Mn) in source / 109.8) x 598.28

LC50 (Mn) in source = 947.6 mg/m³

LC50 (MnGHA) in target = (947.6 / 109.8) x 598.28 = 5163.3 mg/m³

Purity: 66 %

5163.3 / 0.66 = 7823 mg/m³

Since MnGHA contains only 11% of particles that are slightly smaller than 100 µm, no respirable fraction exists in case of dust formation. Thus, the microgranulated product would form only inhalable fraction that would be deposited in the upper airways and can subsequently be swallowed.

Interpretation of results:

other: No C&L is warranted based on this result

Conclusions:

The LC50 value of MnO2 on rats after inhalation exposure converted to manganese glucoheptonate is 7823 mg/m³ for 4 -h exposure time.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

16 082 mg/m³ air

Quality of whole database:

Four study results have been used to cover the information required for the endpoint. The data originate from peer-reviewed public reports or from well conducted tests with sufficient documentation. Since numerous study results exist on effects by inhalation caused by manganese compounds in animals and humans, the data were extracted for soluble and insoluble manganese compounds as well as data sources with effects signed as "serious" to calculate a corresponding LC50 value.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

An estimated oral LD50 value of 3088 mg/kg bw points to very low toxicity potential of MnGHA. The LD50 for MnGHA corresponds to a LD50 of 850 mg/kg bw that was established for MnCl2 in rats (oral).

 

No acute toxicity hazard by inhalation route of exposure can be attributed to Manganese glucoheptonate because no deaths or clinical signs of morbidity or bad health condition are known for inorganic or organic manganese compounds inhaled by animals and humans in numerous short-term or long-term animal studies or in occupational settings, respectively. Using the lowest N(L)OAEC for elemental manganese from inhalation studies of short-durations, surrogate LC50 values have been calculated for the target substance MnGHA. The obtained LC50 values are in the range of 1882 - 16082 mg/m³. The estimated LC50 value of 16082 mg/m³, which is based on oral LD50 of 850 mg/kg bw for Manganese chloride, is selected here for hazard assessment as the most reliable value. Since only 11 % of the particles in the target substance MnGHA are under 100 µm, with no particles having a size below 70 µm, no respirable fraction exists for the target substance, and the dust or aerosol of MnGHA formed would be deposited in upper airways and subsequently swallowed. Thus the LC50 values established in studies with MnO2 or MnCl2, which particles are well of respirable fraction (< 15 µm), may strongly overestimate the hazard of MnGHA by inhalation if they are used for estimation of a corresponding LC50 for MnGHA. Therefore, the oral LD50 is considered as the most reliable starting point for calculation of the corresponding LC50 value.

 

On the basis of the available data, the registered substance does not require classification and labelling for lethal effects following a single oral exposure or exposure by inhalation according to European Regulation (EC) No 1272/2008.