Bis(D-gluconato-O1,O2)zinc

Endpoint summary

Description of key information

A sub-chronic toxicity was performed on rat and mice study was conducted to evaluate the subchronic toxicity (13 weeks) of the test material in mice and Wistar rats. The study followed was similar to OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents).

Mice and rats of both sexes were fed a diet containing the test material at 0, 300, 3,000 and 30,000 ppm for 13 weeks. The clinical signs of the animals, body weight, food, chemical and water intake, food efficiency, haematological, biochemical examination, necropsy and organ weight and histopathological examination were performed.

 

Rats in the 30,000 ppm group showed retarded growth along with low food intake, abnormal values in a few haematological parameters and regressive changes of the pancreatic exocrine gland. There were no remarkable clinical signs in either sex in groups≤3,000 ppm.

Under the test conditions, NOEL of the test material in rats was determined to be 3000 ppm (approximately equivalent to 234 mg/kg/day in male rats and 243 mg/kg/day in female rats).

 

Mice in the 30,000 ppm group showed retarded growth along with low food intake, abnormal values in a few haematological parameters, decreased water intake and significant deviations in biochemical parameters. Histopathological lesions included catarrh at the upper intestine, ulcers at the boundary of fore- and glandular stomach, proliferation of erythropoietic immature cells in the splenic red pulp as well as pancreatic lesions.

Under the test conditions, NOEL of the test material in mice was determined to be 3,000 ppm (approximately equivalent to 458 mg/kg/day in male mice or 479 mg/kg/day in female mice.

 

This study is considered relevant for read-across purpose. A study conducted on wistar rat where zinc gluconate was administered via intraperitoneal route (Andriollo-Sanchez et al.) confirms the read-across approach used.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: oral

Type of information:

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

Adequacy of study:

key study

Study period:

1981

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
The read-across hypothesis is instantaneous dissociation of zinc gluconate into zinc cations (Zn2+) and gluconate anions in aqueous media (environmental compartments and body fluids). Thus, for endpoints where no zinc gluconate data exist, the assessment of the (eco-) toxicological effects can be based on available data of dissociable zinc compounds and gluconate derivatives.
The assessment of human and environmental toxicology is mainly based on the zinc ion, which is considered to be toxicologically more relevant than the gluconate ion (see complete justification report attached).
All of the zinc based read-across partners have in common that they dissociate into zinc and the respective counter ion in aqueous media as described above. The same is true for all of the gluconate based read-across partners, as they dissociate into the gluconate anion and the respective counter ion in aqueous media.
The gluconate derivatives are tentatively ignored for the purpose of this read-across due to the role of gluconates as common additives or nutritional supplements in food and due to the fact that gluconate/gluconic acid is a ubiquitous metabolic product/substrate in mammals with proven low toxicity. As a normal metabolic product of glucose metabolism, 25–30 g are being produced daily in humans. It can safely be concluded that systemic toxicity need not be expected to arise from gluconates/gluconic acid when assessing the potential effects of zinc gluconate. Nevertheless, the lack of toxicological relevance of gluconates is addressed in sufficient detail in the final read-across report targeted at supporting this dossier.
When resorting to dissociable zinc read-across partners, there is a risk of confounding effects that might actually be attributable to the counter ion. The dissociation products of the aforementioned zinc compounds are glycerol, sulphate and chloride ions. The counter ions of the gluconates are sodium, calcium and manganese. All these ions play an important role in the physiology of man and other species. Considering this information, the respective counter ions (calcium, sodium, manganese) are unlikely to contribute to any confounding effects hence do need to be further addressed in this report.

Taking into account the global approach and the detailed explanation (including data matrix and analysis for each endpoint) provided in the report attached, the present read-across is considered relevant.

Reason / purpose for cross-reference:

read-across source

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: Depressed spontaneous motility before death or sacrifice.
- At ≤ 3,000 ppm: No treatment related toxic signs

Mortality:

mortality observed, non-treatment-related

Description (incidence):

- At 30,000 ppm: Four males and one female in this group were found dead or killed in extremis during the study. Histological findings of these animals revealed impairment of the urinary tract and regressive changes in the exocrine gland of the pancreas. Mortality was 33.3% in males and 8.3% in females.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: A more prominently retarded growth resulting in smaller body size than those of other groups.
- At 300 ppm: A significant but very slight depression of weight gain was seen in females for a week after commencement, followed by a rapid recovery to the control level.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: The food intake of male and female mice was depressed during the first week of the study in comparison to that of the controls but showed a tendency to recover afterwards. Average food intake of these animals then remained at only a slightly lower level than that of the control group.

Food efficiency:

effects observed, treatment-related

Description (incidence and severity):

Markedly lower than those of the control group during the first week of the study, corresponding to the decrease in food intake.
-At 30,000 ppm: The overall average food efficiency was much lower than the control group.
- At 3,000 ppm: No data

Water consumption and compound intake (if drinking water study):

effects observed, treatment-related

Description (incidence and severity):

-At 30,000 ppm: Decreased in both sexes during the first week. Though males soon recovered, females showed persistent lower intake during the study.

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Male and female mice in the 30,000 ppm group showed moderately lower values in hematocrit and hemoglobin concentration than those of the control group; the leukocyte count in males also decreased moderately. Morphological changes of erythrocyte anisocytosis, polychromatophilia and poikilocytosis, were seen in six males and four females which were reported by necropsy or microscopic observation to have fore-stomach ulcers. Though some significant fluctuations were seen in hematocrit, no dose dependent abnormalities were found in hemoglobin concentration and erythrocyte count in males or females at less than 3,000 ppm group.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

-At 30,000 ppm: A slight to moderate decrease in total protein, glucose and cholesterol and a moderate to marked increase in alkaline phosphatase and urea nitrogen. Additional significant changes occurring in these animals were depression of SGPT level and increase in calcium level in females, and an increase of SGOT level in males
- At 3,000 ppm: Some fluctuations with significant differences from controls were seen in several parameters but these were all within the acceptable historical limits of mice of this strain and age.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

-At 30,000 ppm: Coincidental increase in absolute and relative weight was found in the thyroids of males and the kidneys of females.
- At ≤ 3,000 ppm: Statistically not significant values when compared to control.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

-At 30,000 ppm: Marked emaciation, ischemic discoloration of the kidney and thyroid, atrophy of the pancreas, edematous thickening of the upper small intestine and slight splenomegaly were recorded in addition to several cases of fore stomach ulcer.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

-At 30,000 ppm: There were lesions attributable to the treatment in the pancreas, upper intestine, stomach, spleen and kidney The pancreatic acinar cells had swollen nuclei with an increased number of clarified nucleoli and whirl-like profiles in their cytoplasm which were more basophilically stained than the controls. Single cell necrosis of the acinar cells was also a common feature in these animals. Moreover, a decrease in the number of acinus and ductule like metaplasia of acinar cells was demonstrated. There was mucosal catarrh in the upper intestine with proliferation of epithelial cells and edema at lamina propria, slight to moderate ulcerative lesions in the boundary of the fore-stomach and proliferation of erythropoietic immature cells in the splenic red pulp of these animals. Regressive changes of the renal cortex were observed in the females.
- At ≤ 3,000 ppm: Statistically not significant values when compared to control

Histopathological findings: neoplastic:

no effects observed

Dose descriptor:

NOEL

Effect level:

3 000 ppm

Based on:

test mat. (total fraction)

Sex:

male/female

Remarks on result:

other: approximately equivalent to 458 mg/kg/day on male, 479 mg/kg/day on female.

Dose descriptor:

LOEL

Effect level:

30 000 ppm

Based on:

test mat. (total fraction)

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical biochemistry

clinical signs

food consumption and compound intake

food efficiency

gross pathology

haematology

histopathology: non-neoplastic

organ weights and organ / body weight ratios

water consumption and compound intake

Critical effects observed:

yes

Lowest effective dose / conc.:

30 000 ppm

System:

immune system

Organ:

leucocyte development

Treatment related:

yes

Critical effects observed:

yes

Lowest effective dose / conc.:

30 000 ppm

System:

gastrointestinal tract

Organ:

intestine

kidney

pancreas

spleen

stomach

Treatment related:

yes

Critical effects observed:

yes

Lowest effective dose / conc.:

30 000 ppm

System:

haematopoietic

Organ:

erythrocyte development

Treatment related:

yes

Conclusions:

Under the test conditions, the NOEL of the test material in mice was determined to be 3,000 ppm (approximately equivalent to 458 mg/kg/day in male mice or 479 mg/kg/day in female mice). This study is considered relevant for read-across purpose.

Executive summary:

A study was conducted to evaluate the sub chronic (13 wk) toxicity of the test material in ICR mice. The study followed was equivalent or similar to OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents).

Mice of both sexes were fed a diet containing test substance at 0, 300, 3000 and 30000 ppm for 13 wk. The clinical signs of the animals, body weight, food, chemical and water intake, food efficiency, hematological, biochemical examination, necropsy and organ weight and histopathological examination were performed.

Animals in the 30,000 ppm group showed retarded growth along with low food intake, abnormal values in a few hematological parameters, decreased water intake and significant deviations in biochemical parameters. Histopathological lesions included catarrh at the upper intestine, ulcers at the boundary of fore- and glandular stomach, proliferation of erythropoietic immature cells in the splenic red pulp as well as pancreatic lesions.

Under the test conditions, NOEL of the test material in mice was determined to be 3,000 ppm (approximately equivalent to 458 mg/kg/day in male mice or 479 mg/kg/day in female mice. This study is considered relevant for read-across purpose.

Reference 2

Endpoint:

sub-chronic toxicity: oral

Type of information:

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

Adequacy of study:

key study

Study period:

1981

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
The read-across hypothesis is instantaneous dissociation of zinc gluconate into zinc cations (Zn2+) and gluconate anions in aqueous media (environmental compartments and body fluids). Thus, for endpoints where no zinc gluconate data exist, the assessment of the (eco-) toxicological effects can be based on available data of dissociable zinc compounds and gluconate derivatives.
The assessment of human and environmental toxicology is mainly based on the zinc ion, which is considered to be toxicologically more relevant than the gluconate ion (see complete justification report attached).
All of the zinc based read-across partners have in common that they dissociate into zinc and the respective counter ion in aqueous media as described above. The same is true for all of the gluconate based read-across partners, as they dissociate into the gluconate anion and the respective counter ion in aqueous media.
The gluconate derivatives are tentatively ignored for the purpose of this read-across due to the role of gluconates as common additives or nutritional supplements in food and due to the fact that gluconate/gluconic acid is a ubiquitous metabolic product/substrate in mammals with proven low toxicity. As a normal metabolic product of glucose metabolism, 25–30 g are being produced daily in humans. It can safely be concluded that systemic toxicity need not be expected to arise from gluconates/gluconic acid when assessing the potential effects of zinc gluconate. Nevertheless, the lack of toxicological relevance of gluconates is addressed in sufficient detail in the final read-across report targeted at supporting this dossier.
When resorting to dissociable zinc read-across partners, there is a risk of confounding effects that might actually be attributable to the counter ion. The dissociation products of the aforementioned zinc compounds are glycerol, sulphate and chloride ions. The counter ions of the gluconates are sodium, calcium and manganese. All these ions play an important role in the physiology of man and other species. Considering this information, the respective counter ions (calcium, sodium, manganese) are unlikely to contribute to any confounding effects hence do need to be further addressed in this report.

Taking into account the global approach and the detailed explanation (including data matrix and analysis for each endpoint) provided in the report attached, the present read-across is considered relevant.

Reason / purpose for cross-reference:

read-across source

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: Showed symptom of discarding the diet from the food jar by picking it out with their fore-limbs. This symptom began a week after commencement of the experiment and persisted throughout the study. No moribund animals of either sex were found.
- At ≤ 3,000 ppm: No remarkable signs in either sex.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

- At 30,000 ppm: No moribund animals of either sex were found.
- At ≤ 3,000 ppm: Two females, one of the control and one of the 3,000 ppm group, were killed in extremis due to suppurative pyelitis during the study.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: Depressed weight gain and dwarfism. Weight gain of females in this group was slightly depressed during the study with significant differences to control animals in the 1st to 5th week of the study.
- At ≤ 3,000 ppm: Statistically not significant values when compared to control

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: Food intake of males decreased after the third wk of the study. A similar reduction was seen in females of this group during the 1st to 6th wk but then disappeared. A slightly lower value of average food and water intake was reported only in males.
- At ≤ 3,000 ppm: Statistically not significant values when compared to control

Food efficiency:

effects observed, treatment-related

Description (incidence and severity):

There were some fluctuations in food efficiency in each group.
- At 30,000 ppm: Slight reduction in overall average value.
- At ≤ 3,000 ppm: Statistically not significant values when compared to control

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: A moderate reduction in leukocyte count was shown in both sexes. Males showed a slight decrease in hematocrit and hemoglobin concentration.
- At 3,000 ppm: No remarkable changes in animals but there was a slight increment of hemoglobin concentration in females

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Significant reductions or reductive tendencies were seen in rats in the following parameters: SGOT and SGPT in all male groups, total protein, cholesterol and calcium levels in males in the 30,000 ppm group and calcium level in females in both the 3,000 and 30,000 ppm groups.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

- At 30,000 ppm: A slight or moderate decrease in absolute and relative weights was seen in the liver and kidney among males
- At ≤ 3,000 ppm: Statistically not significant values when compared to control
- Significant fluctuations of absolute or relative organ weights were seen in various organs from chemically treated groups, no clear relationship with the treatment could be shown.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No remarkable lesions were attributable to the treatment.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

- At 30,000 ppm: Pancreatic lesions as well as degeneration and necrosis of the acinar cells, clarification of centroacinar cells and interstitial fibrosis. No other lesions attributable to the treatment.
- No histopathological abnormalities were observed in the bone or male genital organs which had elsewhere been reported to have sustained toxic changes due to an overdose of Zinc.

Histopathological findings: neoplastic:

no effects observed

Dose descriptor:

NOEL

Effect level:

3 000 ppm

Based on:

test mat. (total fraction)

Sex:

male/female

Remarks on result:

other: approximately equivalent to 234 mg/kg/day on male, 243 mg/kg/day on female.

Dose descriptor:

LOEL

Effect level:

30 000 ppm

Based on:

test mat. (total fraction)

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical biochemistry

clinical signs

food consumption and compound intake

food efficiency

haematology

histopathology: non-neoplastic

organ weights and organ / body weight ratios

Critical effects observed:

yes

Lowest effective dose / conc.:

30 000 ppm

System:

immune system

Organ:

leucocyte development

Treatment related:

yes

Critical effects observed:

yes

Lowest effective dose / conc.:

30 000 ppm

System:

gastrointestinal tract

Organ:

pancreas

Treatment related:

yes

Conclusions:

Under the test conditions, NOEL of the test material in rats was determined to be 3,000 ppm (approximately equivalent to 234 mg/kg/day in male rats and 243 mg/kg/day in female rats). This study is considered relevant for read-across purpose.

Executive summary:

This study was conducted to evaluate the subchronic toxicity (13 weeks) of the test material in Wistar rats. The study followed was similar to OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents).

Rats of both sexes were fed a diet containing the test material at 0, 300, 3,000 and 30,000 ppm for 13 weeks. The clinical signs of the animals, body weight, food, chemical and water intake, food efficiency, hematological, biochemical examination, necropsy and organ weight and histopathological examination were performed.

Animals in the 30,000 ppm group showed retarded growth along with low food intake, abnormal values in a few hematological parameters and regressive changes of the pancreatic exocrine gland. There were no remarkable clinical signs in either sex in groups ≤ 3,000 ppm.

Under the test conditions, NOEL of the test material in rats was determined to be 3000 ppm (approximately equivalent to 234 mg/kg/day in male rats and 243 mg/kg/day in female rats).

This study is considered relevant for read-across purpose.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

234 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Justification for classification or non-classification

Considering that the lowest NOAEL observed in both rats and mice (male & femal) is 234 mg/kg/day in a subchronic toxicity study (conducted on 90 days), and considering the guidance value provided in the guidance on the application of the CLP criteria (version 5.0 of July 2017, §3.9.2.2. page 464) for the category 2, which is 100 mg/kg bw/d for a 90-day study, the substance is considered as not classified under CLP regulation.