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Hydrofluorosilicic acid is an additive used to fluoridate community water supplies in the U.S.
Like many chemicals, it is caustic in its concentrated form. But it never reaches consumers, and the resulting fluoride it produces is diluted in water treatment plants to a safe amount in drinking water.
Toothpastes made by Colgate and other companies use different fluoride compounds, typically stannous fluoride, sodium fluoride or sodium monofluorophosphate.
Can a substance that requires crews to wear hazardous materials gear to clean it up after a spill be safe to drink or use to brush your teeth?
"Fluoride exposed," reads the caption on a Facebook reel posted on June 24, 2022. The video’s narrator said he’s heard a lot about fluoride safety, so he went to the website of Colgate, the maker of toothpaste and other consumer hygiene products. He sarcastically highlighted the site’s claim that fluoride is "safe and effective."
"Now when this very safe chemical spills, this is who comes to clean it up," the narrator said, showing an image of workers in hazmat suits cleaning up what he said was a spill in Ohio. He said the chemical "will literally eat a hole through a road if it’s spilled on, but it’s for your teeth," implying that it’s not safe to use.
The post was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)
A reverse image search shows that the images of crews in hazmat gear o are from a 2011 video report from WQAD — an ABC TV station in Moline, Illinois — about a spill of hydrofluorosilicic acid in nearby Rock Island (not in Ohio, as the video claims). An article on that station’s website said the chemical leaked from a tanker truck at a water treatment plant, where it was being used to add fluoride to the plant’s water supply.
A fire official in the report described the chemical as a "corrosive agent," and the article said it had begun eating through concrete before crews safely contained the spill.
The claim that because the chemical that spilled is corrosive, it’s not safe in your toothpaste is wrong on a couple of points, experts told PolitiFact. It misunderstands both the process used to fluoridate drinking water and what type of fluoride is in your toothpaste.
"This type of misleading information is commonly spread by fluoridation opponents who have little or no understanding of the science of water fluoridation," said Steven Slott, a spokesperson for the American Fluoridation Society, a group promoting community water fluoridation.
First, the hydrofluorosilicic acid, which the Centers for Disease Control and Prevention says is one of three types of fluoride additives used in U.S. water supplies, arrives at water treatment plants in concentrated form.
Like any chemical, hydrofluorosilicic acid can be dangerous to people who come into contact with it, such as in the spill referenced in the video, experts said. But water treatment plants are equipped to handle such chemicals, and HFA doesn't actually reach consumers. The fluoride produced by it is then diluted to safe levels in the water supply.
"One drop of that fluoride additive in its concentrated form is diluted by 250,000 drops of water. The resultant fluoride concentrations delivered to homes and businesses for the community is at a concentration that is at 0.7 parts per million," said Dr. Howard Pollick, a spokesperson on fluoridation for the American Dental Association. Pollick is also a consultant on fluoridation for the California Department of Public Health and a professor at the University of California, San Francisco School of Dentistry.
"This has been established as the effective and safe concentration of fluoride in drinking water to help prevent tooth decay, which can be a very serious disease if it's not prevented or taken care of," Pollick said.
Hydrofluorosilicic acid is actually not fluoride, said Slott, who described fluoride as an anion, or a negatively charged atom, of the naturally occurring element, fluorine. Here’s how he explains the science behind water fluoridation with this particular additive.
"HFA is a compound containing this ion, which is used as a vehicle to add these ions to water that has an insufficient amount of existing fluoride ions to prevent dental decay. The fluoride ions added with HFA are identical to those which already exist in water naturally. They are all sourced from the same rocks in nature," Slott said.
Once it’s added to water, the acid "immediately and completely hydrolyzes," or dissociates, into fluoride ions and an insignificant amount of trace contaminants, he said.
"At this point, HFA no longer exists in the water. It is gone prior to leaving the treatment plant. HFA therefore does not reach the tap and is not consumed by anyone," Slott said.
Pollick said fluoride is just one of several additives used in water treatment. Others are used "to regulate bacteria, to regulate viruses, to regulate other kinds of substances that get into water."
He added that water treatment plants have safeguards to ensure that levels of fluoride or any other additive do not exceed safe levels.
The fluoride in your toothpaste does not contain the hydrofluorosilicic acid used to add fluoride to drinking water, Pollick said.
"It's very different. There are many, many different kinds of fluoride compounds," he said. "The compounds in fluoride toothpaste are typically stannous fluoride or sodium fluoride or monofluorophosphate."
Those are added to the products at safe levels, "about 1,000 parts per million," Pollick said.
Colgate’s website lists all three of those as ingredients in its products.
A Facebook video claims that because a chemical used to fluoridate water supplies spilled and required crews in hazmat gear to clean it up, fluoride isn’t safe to use in toothpaste.
The chemical spill referenced in the video was hydrofluorosilicic acid, which can indeed pose a danger in concentrated form to someone who touches it. But when it’s used to fluoridate water supplies, the acid turns into fluoride ions and is diluted to safe levels. The hydrofluorosilicic acid doesn’t leave the treatment plant, experts said.
Also, toothpastes do not use hydrofluorosilicic acid, but rather one of three types of fluoride compounds, again diluted to safe levels.
We rate this claim False.
UPDATE, July 13, 2022: This story has been updated to add more details about the process through which hydrofluorosilicic acid is used to fluoridate water. The rating remains the same.
Facebook post, June 24, 2022
WQAD.com, "Hazmat crews respond to chemical spill at Rock Island water treatment plant," archived, March 24, 2011
WaterLoo Watch video, YouTube, "Rock Island Illinois Hydrofluorosilicic Acid Spill & Clean-up WQASD News 24-Mar-11"
Phone interview with Dr. Howard Pollick, spokesperson on fluoridation for the American Dental Association, fluoridation consultant for the California Dept. of Public Health and professor at the University of California, San Francisco School of Dentistry, July 12, 2022
Email interview with Steven Slott, a spokesperson for the American Fluoridation Society, July 12, 2022
American Dental Association, "Fluoridation FAQs," accessed July 11, 2022
American Fluoridation Society, "Fluoridation facts," accessed July 11, 2022
Centers for Disease Control and Prevention, "About Fluoride," accessed July 11, 2022
Centers for Disease Control and Prevention, "Water Fluoridation Additives," accessed July 11, 2022
Centers for Disease Control and Prevention, "Other fluoride products," accessed July 11, 2022
Centers for Disease Control and Prevention, "Over 75 Years of Community Water Fluoridation," accessed July 11, 2022
National Institutes of Health, Office of Dietary Supplements, "Fluoride," accessed July 11, 2022
Colgate, " Can You Have Too Much Fluoride? Get The Facts," accessed July 11, 2022
Colgate, "Learn more about what's in our products," accessed July 11, 2022
PolyProcessing, "Designing Proper Hydrofluorosilicic Acid Storage," accessed July 12, 2022
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