Disodium hexafluorosilicate

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to generally valid procedures and according to GLP guidelines. All parameters described are closely related or comparable to guideline methods.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Sodium fluoride

EC Number:

231-667-8

EC Name:

Sodium fluoride

Cas Number:

7681-49-4

IUPAC Name:

sodium fluoride

Details on test material:

- Name of test material (as cited in study report): D0028.03
- Physical state: white powder
- Analytical purity: 100%
- Lot/batch No.: 3
- Storage condition of test material: refrigerated

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, NC, USA
- Age at study initiation: 22 days
- Weight at study initiation: 52.7 - 79.8 g for males; 53.8 -77.9 g for females
- Housing: individually in hanging wire-mesh stainless steel cages
- Diet (e.g. ad libitum): Purina Certified Rodent Chow #5002, ad libitum
- Water (e.g. ad libitum): tap water via an automatic waterering system, ad libitum
- Acclimation period: at least one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.5 - 24.4
- Humidity (%): 48 - 82
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

-Dosing was performed once daily by gavage. Test material adhered to the outer wall of the catheter was wiped off with a clean paper towel prior to intubation.
- Dosage volume was 10 mL/kg of body weight/day. This volume was adjusted weekly according to the most recently recorded individual body weight.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Aliquots of 100 mL from each dose level for weeks 1, 2, 3, 4 and 5 were collected and all samples were sent to the sponsor for analysis and verification.

Duration of treatment / exposure:

28 days

Frequency of treatment:

Once per day

Doses / concentrations

Remarks:

Doses / Concentrations:
0 (water), 0.0025%, 0.025% or 0.25% NaF w/w
Basis:
actual ingested

No. of animals per sex per dose:

10 animals per sex per dose

Control animals:

yes, concurrent vehicle

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily, approximately 1 and 6 hours after completion of dosing

BODY WEIGHT: Yes
- Time schedule for examinations: prior to treatment, weekly during the study, and at termination.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: prior to initiation of dosing and at the end of the study
- Dose groups that were examined: all dose groups

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Collected on the day of sacrifice, approximately 24 hours after the last dose
- Anaesthetic used for blood collection: No data
- Animals fasted: Yes
- How many animals: 10 per sex per group
- Parameters examined: hemoglobin, hematocrit, mean cell volume, mean cell hemoglobin, mean cell hemoglobin concentration, leukocyte count, platelet count, erythrocyte count, corrected leukocyte count, leukocyte differential and cell morphology.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Collected on the day of sacrifice, approximately 24 hours after the last dose
- Animals fasted: Yes
- How many animals: 10 per sex per group
- Parameters examined: strontium*, calcium, inorganic phosphorus, sodium, potassium, choride, magnesium, zinc*, alkaline phosphatase, aspartate aminotransferase, albumin/globulin ratio, alanine aminotransferase, albumin, gamma glutamyltransferase, total bilirubin, direct bilirubin, total protein, blood urea nitrogen, glucose, creatinine, fluoride*, and globulin. * = Performed only in the control group and high dose group due to insufficient sample size, fluoride values were not able to be determined.

URINALYSIS: Yes
- Time schedule for collection of urine: Collected during the 24 hour period prior to sacrifice.
- Metabolism cages used for collection of urine: No data
- Animals fasted: Yes
- Parameters examined: strontium*, calcium, glucose, ketones, phosphorus, sodium, potassium, chloride, magnesium, zinc*, appearance, microscopic examination of sediment, urobilinogen, occult blood, volume, pH, specific gravity, fluoride*, bilirubin, protein, urinary sodium excretion, urinary potassium excretion, urinary chloride excretion, urinary calcium excretion, urinary phosphorus excretion, and urinary magnesium excretion. * = Performed only in the control group and high dose group due to insufficient sample size, fluoride values were not able to be determined.

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
- After 28 days of treatment, all animals were fasted overnight, weighed, anesthetized with sodium pentobarbitol, and exsanguinated.
- The following organs and tissues were examined at necropsy and preserved in 10% neutral buffered formalin: Lungs, thoracic aorta, tongue, trachea, esophagus, thyroid, parthyroid, mandibular lymph node, ileocecal lymph node, stomach, mandibular salivary gland, mandible, liver duodenum, jejunum, ileum cecum, colon, rectum, brain with stem, premaxilla, maxilla, pituitary, skull, eyes, skin (mammary gland), urinary bladder, kidney, testes with epididymides, prostate, seminal vesicle, ovary, uterus, vagina, adrenal (cortex, medulla), thymus, psoas muscle (left), spleen, pancreas, femur (right), femur (left) with stifle joint, patella epiphyseal plate, and tibia (right and left), incisor (upper and lower), third molar, thoracolumbar spinal cord, sciatic nerve (left), caudal vertebra (7th and 8th), fifth rib (right and left), heart and marrow (from femur).
- Any evidence of gastrointestinal tract irritation was recorded.
- The following organs were weighed at necropsy: Adrenals*, brain with stem, kidneys, liver, stomach (after rinsing with saline), ovaries*, testes with epididymides, and heart. * = Weighed postfixation

HISTOPATHOLOGY: Yes
- All tissues from the control group were embedded in paraffin, sectioned, stained with hematoxylin and eosin, and examined microscopically.
- All tissues from the treatment groups remained in fixative and were processed and evaluated if it was deemed necessary.

Statistics:

Absolute body weights, mean body weight changes, and food consumption (through week 4), clinical chemistry, and urinalysis (urine chemistry only), and ogran weight data of the control group were compared statistically to the data from the same sex of the treated groups. Statistical analyses were performed as follows: Bartlett's Test of Homogeneity of Variances was used initally. If homogeneous, an ANOVA was performed, followed by Fisher's LSD Multiple Comparisons test, and finally a Simple Linear Regression and Regression ANOVA (>2 groups) were performed. If heterogenous, an ANOVA was performed followed by either a Modidifed Cochran's t-Test (n < 5) or a Wilcoxan-Mann-Whitney Rank-Sum Test (n = or > 5), and finally a Simple Linear Regression and Regression ANOVA (>2 groups) were performed.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

effects observed, treatment-related

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY
-No clinical signs or mortality were observed during the course of the study.

BODY WEIGHT AND WEIGHT GAIN
- No body weight differences indicative of a test material effect were observed.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
- No food consumption differences indicative of a test material effect were observed.

OPHTHALMOSCOPIC EXAMINATION
- No ophthalmoscopic findings indicative of a test material effect were observed.

HAEMATOLOGY
- Statistical analysis of hematology data revealed a test material-related depression in the mean cell hemoglobin value of high dose rats of both sexes and the mean cell volume of high dose males only when compared to control rats of each sex.

CLINICAL CHEMISTRY
- A statistically significant depression in total protein occurred in high dose males and females.
- Statistically significant increases in alanine aminotransferase, potassium and chloride were noted in high dose females only.

URINALYSIS
- Routine urinalysis was unremarkable, however, urinary mineral values demonstrated a significant increase for fluoride in high dose animals.

ORGAN WEIGHTS
- Organ weight evaluations of the mean values revealed a significantly heavier absolute stomach weight, stomach-to-body weight ratio, and stomach-to-brain weight ratio in high dose males and females.

GROSS PATHOLOGY
- Examination of tissues at gross necropsy did not reveal any effects related to exposure to the test material.

HISTOPATHOLOGY: NON-NEOPLASTIC
- Microscopic examination of tissues did not reveal any effects related to exposure to the test material

OTHER FINDINGS
- Mineral analysis of the teeth revealed significant increases in potassium in high dose males, in fluoride in high dose males and females, and in zinc in ghigh dose females. Strontium values were significantly depressed in high dose males and females when compared to the control animals.
- Mineral anaysis of the femur revealed significantly increased values for magnesium and sodium in high dose males, and zinc and fluoride in high dose males and females.

Effect levels

1

Dose descriptor:

NOAEL

Remarks:

- blood and blood chemistry effects

Effect level:

ca. 25 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

2

Dose descriptor:

NOAEL

Remarks:

- teeth and bone mineral changes

Effect level:

ca. 25 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

3

Dose descriptor:

NOAEL

Remarks:

organ weight changes

Effect level:

ca. 25 ppm

Sex:

male/female

Basis for effect level:

other: Absolute and relative stomach weight values were significantly elevated at 250 ppm

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

In male and female Sprague-Dawley rats dosed by gavage with 0.0%, 0.0025%, 0.025% or 0.25% D0028.03 (sodium fluoride) in water (w/w) for a 28-day period, the following statistically significant changes were observed in rats treated at the high dose (0.25% or 250 ppm) only: 1) significant depression in mean cell hemoglobin of males and females and in mean cell volume of males; 2) significant depression in total protein of males and females and significant increases in alanine aminotransferase, potassium and chloride of females only; 3) significant increase of fluoride in urine of male and females; and 4) significantly heavier absolute stomach weight, stomach-to-body weight ratio, and stomach-to-brain weight ratio for males and females. Mineral analysis of teeth revealed significant increases in potassium in males, fluoride in males and females, and zinc in females. Strontium values were significantly depressed in males and females when compared to the control animals. Mineral anaysis of bone (femur) revealed significantly increased values for magnesium and sodium in males, and zinc and fluoride in males and females.