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Toxicological information

Neurotoxicity

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Description of key information

One published study with sodium fluoride is available. The study was designed to assess the neurotoxicity of sodium fluoride (NaF) in Sprague-Dawley rats. Rats were exposed prenatally, as weanling, or adults. Prenatal exposure - dams were injected subcutaneously with 0.13 mg/kg NaF or saline on gestational days 14 -18 or 17 -19. Weanlings were exposed to NaF in their drinking water at 0, 75, 100 or 125 ppm for 6 to 20 weeks. 3 month old adults received water containing 100 ppm for 6 weeks. Fluoride exposure caused sex and dose specific behavioural disruption (as measured by computer pattern recognition in a novel environment), with a common pattern. Males were most sensitive to prenatal day 17 -19 exposure, whereas females were more sensitive to weanling and adult exposures. After fluoride ingestion, the severity of the effect on behaviour increased directly with plasma F levels and F concentrations in specific brain regions.

Key value for chemical safety assessment

Effect on neurotoxicity: via oral route

Endpoint conclusion
Endpoint conclusion:
no study available

Effect on neurotoxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no study available

Effect on neurotoxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Fluoride exposure caused sex and dose specific behavioural disruption (as measured by computer pattern recognition in a novel environment), with a common pattern. Males were most sensitive to prenatal day 17 -19 exposure, whereas females were more sensitive to weanling and adult exposures. After fluoride ingestion, the severity of the effect on behaviour increased directly with plasma F levels and F concentrations in specific brain regions.

In the absence of water consumption information, it is not possible to calculate the actual received fluoride levels in this study.

Justification for classification or non-classification

No classification is proposed for neurotoxicity according to the CLP Regulation 1272/2008/EC). Classification as a neurotoxicant is assessed as part of STOT-RE classification. The effects observed in the available study are not considered to be indicative of functional impairment, nor is it possible to confirm at which actual received fluoride dose level the observed effects occur.