# Fluoride in water **URL:** \ **Category:** Factual Questions\ **Created:** [January 24, 2011, 5:50pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809 "2011-01-24T17:50:35Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [January 24, 2011, 5:50pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/1 "2011-01-24T17:50:35Z")
Yeah…I know this subject has come up before. I got an email from a friend on this that makes a number of claims, and I’d like to see what the facts are. [Here](http://articles.mercola.com/sites/articles/archive/2011/01/22/does-fluoride-really-fight-cavities.aspx) is the article: > [@](#): > > A new study has found that the protective shield fluoride forms on teeth is up to 100 times thinner than previously believed. This raises questions about how this renowned cavity-fighter really works. > > It has long been believed that fluoride changes the main mineral in tooth enamel, hydroxyapatite, into a more-decay resistant material called fluorapatite. But the new research found that the fluorapatite layer formed in this way is only 6 nanometers thick – meaning it would take almost 10,000 such layers to span the width of a human hair. According to Science Daily: > > ``` > "The scientists question whether a layer so thin, which is quickly worn away by ordinary chewing, really can shield teeth from decay". > > ``` > > Another new study shows that exposure to fluoride may lower children’s intelligence. In addition to toothpaste, fluoride is added to 70 percent of U.S. public drinking water supplies. PR Newswire reports: > > ``` > "About 28 percent of the children in the low-fluoride area scored as bright, normal or higher intelligence compared to only 8 percent in the 'high' fluoride area ... in the high-fluoride city, 15 percent had scores indicating mental retardation and only 6 percent in the low-fluoride city." > > ``` -XT ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [January 24, 2011, 7:40pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/2 "2011-01-24T19:40:41Z")
1. There really was an announcement of measurements showing a thinner fluoride layer than previously believed. I heard about it on Scientific American’s podcast (I think that was it). However, we know that fluoride protects against tooth decay, this just raises some questions about _how_ exactly it does that. 2. Do not ever, ever, believe anything you read on Joe Mercola’s web site. Just like he did here, he may sometimes take a bit of fact to base his story on, but the story he comes up with is guaranteed to be exactly wrong. ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [January 24, 2011, 8:33pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/3 "2011-01-24T20:33:42Z")
That’s what I figured. I was hoping for a bit more that I could toss back to my friend, though I doubt any amount of evidence is going to convince him so there probably is no point. Thanks for the post CurtC! -XT ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [January 24, 2011, 8:45pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/4 "2011-01-24T20:45:38Z")
Your friend seems to believe that flouride forms an “invisible protective shield” around a tooth. [According to this](http://books.google.com/books?id=46o0PzPI07YC&pg=PA494&lpg=PA494&dq=fluoride+tooth+enamel&source=vrt&ots=GiDzhjHDOK&sig=rgHT7SSNHmOOpM1SNZ_Sbd6naS4&hl=en&ei=IOM9TeXqGMOBlAeUncnqBg&sa=X&oi=book_result&ct=result&resnum=11&ved=0CHgQ6AEwCg#v=onepage&q=fluoride%20tooth%20enamel&f=false)its effect seems to me (not a dentist or a chemist) to be more like neutralizing the bad stuff that attacks teeth. ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [January 24, 2011, 8:54pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/5 "2011-01-24T20:54:47Z")
What I told him in reply is that, even assuming fluoride DOES cause the teeth to be thinner or whatever, that doesn’t explain why the overwhelming data has been that putting fluoride in drinking water has caused tooth decay to drop by a large amount over the last century or so. And this at a time when the use of sugary snacks is on the rise and continues to rise. I just dismissed the part about it causing a drop in intelligence, since there would be so many factors (if studies actually even show it to be the case) the isolating for just fluoride would be nearly impossible. It’s sort of like the folks who think that autism is caused by the mercury based preservatives in immunization shots (he also believes in that too, of course). -XT ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [January 24, 2011, 8:55pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/6 "2011-01-24T20:55:29Z")
Here’s a transcript of the podcast I heard: [Podcasts | Scientific American](http://www.scientificamerican.com/podcast/episode.cfm?id=fluorides-dental-dominion-may-remai-10-12-29) Here are the key points: > [@](#): > > But how does fluoride work its magic? Many figured that fluoride chemically reacts with the main mineral in enamel to form a thick, decay-resistant veneer. But the latest research kicks that idea in the teeth. > > … > > How fluoride keeps the tooth fairy away is a mystery that researchers are still working to unravel. In the meantime, we may not know how it works, but we know that it works. So keep brushing. The link to the original journal article is there also. ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [January 24, 2011, 8:59pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/7 "2011-01-24T20:59:41Z")
> [@xtisme](#): > > What I told him in reply is that, even assuming fluoride DOES cause the teeth to be thinner or whatever, that doesn’t explain… No, no, no. The fluoride doesn’t cause anything to be thinner. The new research found that the fluoride doesn’t penetrate as deeply into your enamel layer as they previously thought it did. It’s so much less deep, that our old ideas about _how_ it protects teeth are probably not right, or at least not the whole story. We do, however, still know _that_ it works to greatly reduce tooth decay. ---
**Author:** ![Cat\_Whisperer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cat_whisperer/32/4839_2.png) [@Cat\_Whisperer](https://boards.straightdope.com/u/Cat_Whisperer)\ **Post date:** [January 24, 2011, 9:01pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/8 "2011-01-24T21:01:11Z")
The kind of junk science people like Mercola put out really angers me - it has just enough “ring of truth” in it to fool people who want to be fooled (or don’t want to bother doing any of their own research), so just enough to be dangerous. At least he spelled “fluoride” right. :rolleyes: ---
**Author:** ![PSXer](https://avatars.discourse-cdn.com/v4/letter/p/48db29/32.png) [@PSXer](https://boards.straightdope.com/u/PSXer)\ **Post date:** [January 24, 2011, 9:19pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/9 "2011-01-24T21:19:09Z")
Fluoride in water messes up your bodily fluids. ---
**Author:** ![Cat\_Whisperer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cat_whisperer/32/4839_2.png) [@Cat\_Whisperer](https://boards.straightdope.com/u/Cat_Whisperer)\ **Post date:** [January 24, 2011, 9:48pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/10 "2011-01-24T21:48:22Z")
> [@PSXer](#): > > Fluoride in water messes up your bodily fluids. Well, at least _you_ spelled “fluoride” right. 🙂 ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [January 24, 2011, 9:54pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/11 "2011-01-24T21:54:27Z")
> [@PSXer](#): > > Fluoride in water messes up your bodily fluids. I sure hope you’re quoting **Dr. Strangelove** … > [@General Jack D. Ripper](#): > > you know when fluoridation first began? Nineteen hundred and forty-six. 1946, Mandrake. How does that coincide with your post-war Commie conspiracy, huh? It’s incredibly obvious, isn’t it? A foreign substance is introduced into our precious bodily fluids without the knowledge of the individual. Certainly without any choice. That’s the way your hard-core Commie works. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [January 24, 2011, 9:58pm UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/12 "2011-01-24T21:58:44Z")
> [@PSXer](#): > > Fluoride in water messes up your bodily fluids. i believe it is your precious bodily fluids. ---
**Author:** ![Cat\_Whisperer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cat_whisperer/32/4839_2.png) [@Cat\_Whisperer](https://boards.straightdope.com/u/Cat_Whisperer)\ **Post date:** [January 25, 2011, 1:29am UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/13 "2011-01-25T01:29:00Z")
While we’re at it, what do people think of this study - [The Case Against Fluoride](http://www.chelseagreen.com/bookstore/item/the_case_against_fluoride:paperback)? ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [January 25, 2011, 5:05am UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/14 "2011-01-25T05:05:15Z")
> [@](#): > > In addition to toothpaste, fluoride is added to 70 percent of U.S. public drinking water supplies. I can’t recall that they have ever added toothpaste to the water supply here. How would they even get it to flow through the old iron water supply pipes under the streets? And what about when you are filling your coffee maker, and the faucet spews green & white toothpaste – wouldn’t that mess up the taste of the coffee? 🙂 Isn’t it interesting how poor the writing is on most of these nutcase websites. ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [January 25, 2011, 5:07am UTC](https://boards.straightdope.com/t/fluoride-in-water/568809/15 "2011-01-25T05:07:58Z")
> [@Cat\_Whisperer](#): > > While we’re at it, what do people think of this study - [The Case Against Fluoride](http://www.chelseagreen.com/bookstore/item/the_case_against_fluoride:paperback)? That’s not a study - it’s a book. I don’t much know what to think of it because I haven’t read it, but the fact that they refer to fluoride as “hazardous waste” right in the book’s subtitle doesn’t give me any hope that it should be trusted.