Abstract
The L5178Y mouse lymphoma cell forward-mutation assay was used to test for the mutagenic activity of sodium and potassium fluoride at the thymidine kinase locus. Mutants were detected by colony formation in soft agar in the presence of trifluorothymidine. Mutagenic and toxic responses were observed in the concentration range of 300-600 micrograms/ml with both sodium and potassium fluoride. Approximately 3-fold increases in mutant frequency were observed for concentrations in the 500-700 micrograms/ml range that reduced the relative total growth to approximately 10% in the absence or presence of a rat-liver S9 activation system. A sample of 30% sodium fluoride-70% sodium bifluoride (NaHF2) induced a similar mutagenic response but was more toxic with respect to the fluoride concentration. A specificity for fluoride ions in causing mutagenesis was indicated by the fast that much higher concentrations of sodium or potassium chloride were necessary to cause toxicity and increases in the mutant frequency. The possible involvement of chromosomal changes was signaled by the predominant increase in the small colony class of mutants.
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Extrapolation from in vitro tests to human risk: experience with sodium fluoride clastogenicity
Genotoxic effects observed in vitro, only at high doses or high levels of cytotoxicity, will be false positives if such conditions are not achieved or cannot be tolerated in vivo. However, for such effects to be disregarded there must be a threshold dose or level of cytotoxicity below which genotoxicity
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Cytological effects of sodium fluoride on mice
Inbred mice, fed a low-fluoride diet, 0.263 + 028 ppm F, were given drinking water containing 0, 1, 5, 10, 50, 100, or 200 ppm F for 3 to 6 weeks. Cytological studies on bone marrow cell chromosomes and spermatocytes showed that 1-200 ppm F (as sodium fluoride) was able
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Genotoxic effect of an environmental pollutant, sodium fluoride, in mammalian in vivo test system
Genotoxicity of Sodium fluoride was evaluated in mice in vivo with the help of different cytogenetic assays. The frequency of chromosome aberration was dose - and time - dependent but not exactly route-dependent. Fractionated dosing induced less aberration. Incidence of micronucleus and sperm abnormality increased with dose. Relative sensitivity of
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Chromosomal aberrations and micronuclei in lymphocytes of workers at a phosphate fertilizer factory
The frequencies of chromosomal aberrations (CA) and micronuclei (MN) in peripheral blood lymphocytes of 40 workers at a phosphate fertilizer factory in North China, were studied. HF and SiF4 are the main air pollutants and small amounts of dust containing fluoride, NH3 and SO2 were also present in the factory.
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Genetic toxicity of fluoride
F- is not mutagenic in standard bacterial systems, but produces chromosome aberrations and gene mutations in cultured mammalian cells. Although there is disagreement in the literature concerning the ability of F- to induce chromosome aberrations in cultured human and rodent cells, the weight of the evidence leads to the conclusion
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Fluoride's Mutagenicity: In vitro Studies
According to the National Toxicology Program, "the preponderance of evidence" from laboratory "in vitro" studies indicate that fluoride is a mutagenic compound. Many substances which are mutagens, are also carcinogens (i.e. they can cause cancer). As is typical for in vitro studies, the concentrations of fluoride that have generally been tested
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Fluoride's Mutagenicity: The "Oral Health Research Institute's" Studies
Although many in vitro and in vivo studies have detected mutagenic effects from fluoride exposure, the Oral Health Research Institute at Indiana University's School of Dentistry has repeatedly failed to find any such effect in multiple studies on the subject.
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Micronucleus and Sister Chromatid Exchange Frequency in Endemic Fluorosis
The rise of sister chromatid exchange (SCE) and micronucleus (MN) in the peripheral blood lymphocytes of the fluorine-intoxicated patients indicates that fluorine is a mutagenic agent which can cause DNA and chromosomal damage.
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Fluoride's Mutagenicity: In vivo Studies
Consistent with dozens of in vitro studies, a number of in vivo studies, in both humans and animals, have found evidence of fluoride-induced genetic damage. In particular, research on humans exposed to high levels of fluoride have found increased levels of "sister chromatid exchange" (SCE). As noted in one study: "In
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NTP Bioassay on Fluoride/Cancer (1990)
In 1977, the U.S. Congress requested that animal studies be conducted to determine if fluoride can cause cancer. The result of the Congressional request was an extensive animal study conducted in the 1980s by the National Toxicology Program (NTP) and published in 1990. The main finding of NTP's study was a dose-dependent increase in osteosarcoma (bone cancer) among the fluoride-treated male rats.
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