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Toxicological information

Basic toxicokinetics

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Administrative data

Endpoint:
basic toxicokinetics in vivo
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Published study, methods scientifically acceptable

Data source

Reference
Reference Type:
publication
Title:
Comparison of Fluoride metabolism when administered as NaF or Silicofluorides to rats
Author:
Whitford GM & Johnson NA
Year:
2003
Bibliographic source:
Journal of Dental Research, 82 (Special Issue A): Abstract 81

Materials and methods

Objective of study:
metabolism
Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Investigation of fluoride retention in rats administered different fluoride compounds.
GLP compliance:
not specified
Remarks:
published study

Test material

Constituent 1
Chemical structure
Reference substance name:
Hexafluorosilicic acid
EC Number:
241-034-8
EC Name:
Hexafluorosilicic acid
Cas Number:
16961-83-4
Molecular formula:
F6Si.2H
IUPAC Name:
hexafluorosilicate
Details on test material:
Hexafluorosilicic acid (HFS)
Radiolabelling:
no

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
female
Details on test animals or test system and environmental conditions:
Female weanling Sprague-Dawley. Housed in pairs. Free access to fluoridated food and water.

Administration / exposure

Route of administration:
other: oral (feed and water)
Vehicle:
not specified
Duration and frequency of treatment / exposure:
Free access to fluoridated food and water for 5 months.
Doses / concentrations
Remarks:
Doses / Concentrations:
Hexafluorisilicic acid added to AIN-76A food at 0.7 ppm F; and to deionised drinking water at 24 ppm F.
No. of animals per sex per dose / concentration:
8 female rats per group
Control animals:
not specified
Positive control reference chemical:
The study was a comparison between three substances used to fluoridate water; sodium fluoride (NaF), hexafluorosilicic acid, and sodium fluorosilicate.

Results and discussion

Preliminary studies:
Not relevant

Toxicokinetic / pharmacokinetic studies

Details on absorption:
Not quantified
Details on distribution in tissues:
Not determined
Details on excretion:
In the rats administered hexafluorsilicic acid, fluoride was excreted in the urine and faeces at 336±27 and 153±20 µg/48h, respectively.

Metabolite characterisation studies

Metabolites identified:
not measured
Details on metabolites:
Not determined

Any other information on results incl. tables

Fluoride intake was 36.1±1.7 µg/48-h in the food, and 1532±57 µg/48-h in the water. In rats administered hexafluorosilicic acid, fluoride was excreted in the urine and faeces at 336±27 and 153±20 µg/48-h, respectively. Fluoride balance was 1079±74 µg/48-h, and fluoride retention was 68.1±2.7%. The intake, excretion, balance and retention of fluoride was comparable in the groups administered hexafluorosillicic acid, sodium fluoride and sodium hexafluorosilicate.

Applicant's summary and conclusion

Conclusions:
A comparison between the retention of sodium fluoride, fluorosilicic acid, and sodium fluorosilicate did not find significant differences in the percentage of intake retained in the body of female rats exposed to 24 ppm fluoride in the diet for 5 months; fluoride retentions were 66.2, 68.1, and 64.8 %, respectively.
Executive summary:

The effects of different fluoride salts on the uptake and retention of fluoride were investigated in female rats. A comparison between the retention of sodium fluoride, fluorosilicic acid, and sodium fluorosilicate did not find significant differences in the percentage of intake retained in the body of female rats exposed to 24 ppm fluoride in the diet for 5 months; fluoride retentions were 66.2, 68.1, and 64.8 %, respectively.