Fluoride in your water: How much is too much?

By Sonya Lunder, EWG Senior Scientist

Last month, the U.S. Department of Health and Human Services (HHS) proposed that public water systems cut back on the amount of fluoride they add to drinking water. Whether you live in a city with fluoridated water or not, you're probably aware of the longstanding debate (often more like a battle) over fluoridation.

Over the last several years, Environmental Working Group has carefully reviewed the evidence of fluoride's benefits to teeth - and its potential toxicity - and this week EWG wrote the federal agency urging it to lower fluoride levels even more than it had proposed.

Here's why:

Fluoride strengthens teeth and makes them more resistant to cavities. That's good. But fluoridated water has some significant drawbacks - especially compared to treatments that apply it directly to teeth, such as fluoridated toothpaste or other dental treatments.

  1. Fluoride replaces calcium in teeth and bone. A portion of the fluoride you ingest takes the place of calcium in your teeth and bones. In places where there is lots of fluoride in water, people can develop weaker bones and serious tooth damage known as "fluorosis." Whether lower levels of fluoride have the same effects is not clear, but an estimated 40 percent of Americans have dental fluorosis, ranging from mild to severe.
  2. Toothpaste works just as well, without the downsides. Last year, the European Union concluded that because of these risks, toothpaste and other topical treatments were a better option than fluoridated water.

    In their recent announcement, federal officials cited a review by the US Centers for Disease Control and Prevention as justification for continuing to fluoridate water. But when we read between the lines (a handy skill in our line of work), we noticed that the CDC review found that water fluoridation and toothpaste provide a similar level of protection, at least in adults.

    It's very worth noting that while fluoridated toothpaste contains thousands of times more fluoride than drinking water, it can be used safely to deliver the benefits directly to the teeth while minimizing how much gets into the body and bones.

  3. Drinking water is an inexact delivery route. We can't tailor the amount of fluoride in drinking water for each demographic group. Pregnant women, athletes and people with diabetes all drink lots of water and as a result will likely ingest more fluoride than teens - who are rumored to subsist purely on soda.

Proposed limit not low enough, especially for vulnerable groups The lower fluoride concentrations in drinking water being recommended by the government will still be too high for some groups. EWG estimates that 20 percent of babies less than 2 years old will end up ingesting too much fluoride, particularly babies fed powdered baby formula, which is mixed with water. Because they're so small, bottle-fed babies drink approximately 10 times more water than adults every day.

The first two years of life are a vulnerable, because babies are growing rapidly and more of the fluoride finds a permanent home in their bones or teeth. In short, for infants it's all downside and no benefit. About 10 percent of older children will also get too much fluoride from the combination of drinking water, toothpaste and the small amount of fluoride in food, pesticides and other sources.

About 40 percent of Americans have fluorosis, though it is often very mild. Regardless, we at EWG believe that it just makes sense to minimize fluoride ingestion until the safety of the proposed lower levels can be assured. Although current drinking water guidelines focus on fluoride toxicity to bone and teeth, studies from regions with high levels of naturally occurring fluoride have also found indications of neurotoxicity and hormone disruption, and even increased rates of a rare type of bone cancer in boys.

Better than nothing, but not enough EWG does welcome this move to lower fluoride levels - for years we've been concerned about the safety of water fluoridation. That said, federal agencies haven't fully tallied the risks of fluoride and the potential to administer it more safely. The Environmental Protection Agency published a toxicity assessment that concluded that adding fluoride at 0.7 parts per million is safe, but based its calculations on some questionable assumptions. Without them, the assessment would have shown the opposite. The point is, fluoride belongs ON your teeth, not IN your body. Surface application works and is safe - as long as kids learn to spit out their toothpaste (harder than you might think!).

Key fluoride tips for water drinkers It's good news that the federal government wants to reduce the allowable fluoride levels in drinking water. But EWG doesn't think their proposal goes far enough, so we encourage you to take precautions at home. These are our top tips:

  • NO fluoride for babies. The American Dental Association (ADA) says there is no proof of benefits before teeth emerge. Avoid mixing powdered or concentrated baby formula with fluoridated water.
  • NO fluoridated toothpaste for children younger than two.
  • Use less toothpaste. Use a pea-size amount of child-strength toothpaste for bigger kids, but only once they can reliably rinse and spit
  • Rinse, don't chew. If you are considering a fluoride supplement, look for rinses instead of chewable tablets to lessen the amount that ends up inside your child's body.
  • Alert your tap water provider. If you live in an area with fluoridated water (find out here), let your water utility know about the new federal guidance. Fluoride levels in water should not exceed 0.7 parts per million.

[A big thanks to Flickr CC & Gustty for the pearly whites]

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