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Hydrofluoric Acid aka Hydrogen Fluoride

Dr. Richard Sauerheber & James Robert Deal

Silicofluoride is composed of and breaks down into hydrogen fluoride and other components. Hydrogen fluoride is the most immediately toxic component in silicofluoride. Because its charge is neutral (FH+), it can slip easily through the neutral, non-polar, fatty lipid layer of the stomach lining, and then into the blood stream and the brain.

Seattle, Everett, and Tacoma all use silicofluoride which is composed of and breaks down into hydrogen fluoride in the acidic stomach. Hydrogen fluoride is also referred to as “free acid”[44]. See the Simplot Certificate of Analysis[45] for Everett and the Mosaic Certificate of Analysis[46] for Seattle on the page.

An FDA regulation at 21 CFR 310.545 prohibits the marketing and sale of any anti-caries drug which contains hydrogen fluoride unless the seller has first filed an FDA new drug application[43] (NDA) and received FDA approval.

Said federal regulation includes a list of elements and compounds, including hydrogen fluoride. The regulation says of the chemicals on the list:

…based on evidence currently available, there are inadequate data to establish general recognition of the safety and effectiveness of these ingredients for the specified uses.

Then the regulation states:

Any OTC [over the counter] drug product … containing any active ingredient(s) as specified in … this section is regarded as a new drug within the meaning of … the Federal Food, Drug, and Cosmetic Act (the Act), for which an approved new drug application … is required for marketing.

Fluoride used for water fluoridation is being treated as an unapproved but permitted over-the-counter drug. It contains HF and therefore should not be utilized until prior approval has been obtained from the FDA.

This FDA hydrogen fluoride regulation is unenforced. Is it overlooked or just plain ignored? In the fluoridation arena you will find many uninforced, overlooked, and ignored laws. Fluoridation – initially with sodium fluoride – got started during World War II and the Cold War. The military, ALCOA, and other industries backed it. They latched onto a legend that natural fluoride in Texas and Colorado reduced decay, although the basis for the reduction was the high calcium levels, not the fluoride. These powerful groups generally got their way during that era. They rewarded universities for supporting fluoridation. The universities graduated physicians and dentists who became featured speaker “trusted professionals”, endorsers and defenders of fluoridation. Most of the “trusted professionals” we rely on are themselves deceived. Fluoridation began without prior approval by any federal or state agency. Since 1945 no agency has had the courage to stop it.


Hydrofluoric acid, also known as hydrogen fluoride or HF, freely permeates through the cell membrane bilayer because HF is neutral in charge and is a small molecule, comparable in size to the water molecule which also freely diffuses across cell membranes (see Whitford, G.M., Sampaio, F.C., Pinto, C.S., Maria, A.G., Cardoso, V.. Buzalaf, M., Pharmacokinetics of ingested fluoride: Lack of effect of chemical compound, Archives of Oral, Biology, 53 (2008) 1037–1041).

Fluorosilicic acid ionizes in municipal water supplies to form H+, protons having a positive charge, and F-, negatively charged fluoride ions. The extent of dissociation depends on the acidity of the water, since H+ and F- remain bonded as the neutral molecule HF in acidic water. HF is a covalent, not an ionic, bond and, being a weakly dissociating acid, remains largely intact, as the uncharged molecule, under acidic conditions. The degree of ionization of HF depends on prevailing pH.  HF only ionizes in the presence of water, which is H+OH-. Below pH 7 there are excess H+ ions (compared to hydroxide OH ions), so a drop in pH means an increase in the concentration of H+ protons. Although most HF is ionized coming into homes from the public treated water supply, at acidic pH in the stomach after ingestion, more F- combines with H+ to form the neutral, membrane-permeating hydrofluoric acid HF.

Membranes have a bulk matrix that is a nonpolar lipid bilayer which resist permeation by ions, for example F, because charged species are very polar and water soluble, and not soluble in hydrophobic nonpolar lipid. Neutral molecules on the other hand can pass through the membrane bilayer, depending on the lipid solubility of the molecule and in the case of polar HF, its small size.

HF easily passes through the membrane fatty lipid bilayer of cells surrounding the stomach to gain entry into the bloodstream. Here, at an acidic pH of 3.6, HF is the predominant species that is freely assimilated after ingestion of fluoride, because stomach contents are highly acidic, causing typically about 50% of all ingested fluoride ion to form HF.

Leaving the stomach and entering the blood, where the pH is buffered to be alkaline at 7.4, HF mostly dissociates back to hydrogen ions and free fluoride ions. Any HF present in minute amounts in the blood could also pass through the blood-brain barrier and other organ membranes the same way. However, because the concentration of HF present in alkaline conditions is much lower than in acidic conditions, the precise mechanism by which fluoride ion accumulates into brain and other cells is currently not known with certainty.

The extremely small size of the HF molecule at 2.7 Angstroms makes HF the most penetrating of all acids and extremely toxic and dangerous. In well-controlled experiments with 1 ppm synthetic sodium fluoride water ingested by human volunteers, stomach discomfort caused by HF corrosivity is significant in 1% of the subjects. HF burns on skin surfaces are not immediately painful as are burns with strong acids like sulfuric or hydrochloric, but pain is evident as the tissue is slowly penetrated and dissolved. The concentration of HF present in the human drinking water clinical study were extremely minute and yet sufficient to cause gastric pain. HF formation is decreased in the presence of dietary calcium, where fluoride is highly attracted naturally to calcium ion in water, so water hardness lowers HF levels by competing for the binding of fluoride ion. Everett water is extremely low in calcium and other minerals, meaning that consumers in Everett are more impacted by fluoridation than elsewhere.

In our experiments HF was measured indirectly with an ion specific fluoride electrode as a function of wide variations in pH. The data were plotted and demonstrate as expected a biphasic curve where 50% of total fluoride is in the form of HF at stomach pH (Sauerheber, R., submitted to Journal of Toxicology and Pharmacology, 2012, letter # 6 in the 21 Letter Series to the FDA).

Consistent with the above discussion, the National Research Council Report on Fluoride in Drinking Water, A Scientific Review of EPA’s Standards, 2006, Washington, D.C., pp. 268-280 contains the following statements:

When ingested, some fluoride combines with hydrogen ion to form HF, 2.4% at pH 5, and 96% at pH 2.  HF easily crosses the gastric epithelium and is the major form in which fluoride is absorbed form the stomach. HF dissociates upon entering the interstitial fluid. The primary symptoms of fluoride induced gastrointestinal injury are nausea, vomiting, and abdominal pain, and have been reported in human case studies by Waldbott (1956) and Petraborg (1977) and in a clinical study involving double blind tests on subjects drinking water fluoridated at 1 ppm (Grimbergen, 1974).  Symptoms were reported in 1% of subjects for either sodium fluoride or sodium silicofluoride water at 1 ppm fluoride. Although less than 1% of a population complains of GI symptoms after water fluoridation, the absence of symptoms in some may be related to hardness of the water. Chronic ingestion of fluoride water [lacking calcium] on an empty stomach is more likely to elicit symptoms.

It is clear that for any subject having ulceration of gastric tissue, fluoride water consumption is contraindicated and would certainly be expected to slow healing of ulcers. Although HF is a weak acid with dissociation constant 6.5 x 10-4 and is present at only 0.5 ppm in stomach fluid (half of the 1.0 ppm fluoride total) understand that HF is officially listed as extremely corrosive, highly irritating and poisonous and that at sufficient concentrations (in the absence of antidote calcium) causes severe burns which may not be painful or visible for several hours and slowly etches and dissolves glass (Merck Index, 1976, Rahway, N.J., p. 632).

The U.S. Food and Drug Administration in its Code of Federal Regulations of the Food Drug and Cosmetic Act specifically prohibits sale or use of any substance taken orally that contains appreciable HF without a new drug application for approval. Currently no fluoride compound, including HF, is approved for ingestion by the FDA in the United States. And yet, the private organization the National Sanitation Foundation currently certifies fluorosilicic acid preparations for use in public water supplies that contain HF, in stark contrast to this FDA ruling. NSF regulations do not allow certification if the fluorosilicic acid contains more than 1% HF, and yet certified batches have been delivered to Everett that have been assayed to contain 2% HF. Ironically, our data demonstrates that regardless of HF content or its absence (as in sodium fluoride used in some water supplies) 50% of ingested fluoride converts to HF in the acidic stomach.


A 23% fluosilicic acid solution, because of the chemistry of aqueous fluorides, typically contains around 1.5 % HF (as assayed by Lucier Chemicals for Metropolitan Water, Los Angeles).

This is 23 grams of H2SiF6 and 1.5 grams of HF per 100 grams of solution, which is 18 grams of fluoride from H2SiF6 and  1.5 grams of fluoride from HF.

Thus, in Los Angeles 8% of all fluoride present in the solution is HF.

The Code of Federal Regulations specifically and explicitly prohibits the marketing, interstate transport, or ingestion of any anti-caries agent that contains HF without a new drug application – NDA.

Fluosilicic acid hazardous waste preparations are currently diluted into nearly 70% of all U.S. water supplies without FDA approval and without a prescription. A 1.0 ppm fluoridation level produces 0.21 ppm anionic fluorine in human blood, and such action requires an FDA ban, or an approved NDA.

Here also is the calculated HF concentration that would be present in the stomach if one were thirsty and filled up from drinking 1 ppm fluoride water. That is:

HF  produces H+ and F as a weak acid with dissociation constant Ka = 7.2 x 10-4 (CRC Handbook for Chemistry and Physics)

So 7.2 x 10-4 = [H+][F]/[HF] where [F], after combining with stomach acid H+, = 5.2 x 10-5M – X (1 ppm in molarity units minus the unknown molarity X for HF)

Rearranging, 7.2 x 10-4X = [10-3][5.2 x 10-5 – X]  and 0.00172X = 5.26 x 10-8

Solving,  X = 3 x 10-5 M HF in stomach acid, which is 0.6 ppm HF.

This agrees with experimental observations with a fluoride ion specific electrode at pH 3, where 1 ppm fluoride water is detected as only approximately 0.5 ppm. This level of HF is a significant concentration of this uncharged tissue-penetrating corrosive in contact with stomach mucosal tissue.

I will be calling this to the attention of the FDA.

I calculated the concentration of HF that would be present in a solution that is buffered to pH 7 with 1 ppm total fluoride and it is about 0.14 ppb of this corrosive substance HF. This would be unimpressive to those promoting fluoride to be concerned about, but nevertheless it is the most corrosive substance known and is the active ingredient in industrial uses on glass, ceramics, computer chips, etc. when conditions are not buffered. In plain water without buffering, the HF is higher.

Richard Sauerheber, Ph.D.
(B.A. Biology, Ph.D. Chemistry, University of California, San Diego)
Palomar College, San Marcos, CA  Phone: 760-744-1150 xt 2448

Check back. More material on HF will be consolidated here.

1 Comment

  1. Brent

    I am looking for a way to treat my drinking ng water before i drink it. Is there a way to change the ph then add a natural non harmful substance to my water that will break or bind up the HF so it will pass through my system and not cross the blood brain barrier.


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