Smarter Living: Chemical Index

Fluoride dental products help fights cavities but drinking it can be harmful.

What Is It?

Fluoride is a naturally occurring mineral that prevents tooth decay when applied to the surface of teeth, such as by using fluoridated toothpaste or mouthwash. In addition to its use in toothpaste, mouth rinses, and other dental hygiene products, fluoride may be added to drinking water supplies as a community-wide effort to prevent cavities. In some parts of the U.S., naturally-occuring fluoride seeps into groundwater from geologic deposits. These exposures from ingesting fluoride-contaminated drinking water have raised serious health concerns among experts.

Health Concerns

Although small amounts of fluoride applied topically to the surface of teeth can help to prevent cavities, but ingesting it can cause yellow or brown stains and pits to form in the tooth enamel. This enamel or dental fluorosis occurs in children that eat or drink high amounts of fluoride during tooth formation in the first eight years of life.

An increased risk of bone fracture may occur in children and adults who regularly drink water containing more than 4 milligrams fluoride per liter of water, the federal Maximum Contaminant Level (MCL). Over time, fluoride can accumulate in the bones, and levels above 4 mg/l can lead to a condition called skeletal fluorosis. People with skeletal fluorosis suffer from chronic joint pain, arthritic symptoms, and reduced flexibility.

Fluoride can decrease thyroid hormone activity and it has other hormone-disrupting effects. It was found to harm brain development and behavior in one study of children, and animal studies hint at links to reduced fertility and birth defects, but these areas require further study.

Fluoride has been studied for links to osteosarcoma, a form of bone cancer. A 2006 study in the journal Cancer Causes & Control found an association between drinking fluoridated water during childhood and risk of developing osteosarcoma in young men but not women. Further studies need to be done to confirm this result.


The main sources of fluoride are drinking water, food, and dental products and treatments. Roughly 190 million people in the U.S. drink fluoridated water, according to a 2008 survey by the Centers for Disease Control and Prevention (CDC). Sodas and other beverages made with fluoridated water also contribute to overall fluoride intake. In some parts of the country, fluoride occurs naturally in water at unsafe levels, and water companies must reduce it to the federally mandated level of 4 milligrams/liter, but this level is not stringent enough to protect sensitive populations such as children, according to a 2006 study carried out by the U.S. National Research Council, a government body of scientists. People who draw from private wells may drink high levels of fluoride.

Food can contain fluoride either because it was prepared with fluoridated water or because it was treated with sulfuryl fluoride, a fumigant that is sprayed in grain mills, bakeries, and food-processing facilities on cereal grains, dried fruits, nuts, cocoa beans, coffee and other foods. Sulfuryl fluoride accounts for less than three percent of total exposure to fluoride, according to the U.S. Environmental Protection Agency (EPA). Due to health concerns about the exposure from multiple sources, the EPA is phasing out these usages of sulfuryl fluoride.

With so many sources of fluoride available today, many people are getting too much, according to the U.S. Department of Health and Human Services (HHS) and the EPA. Infants and young children ingest three to four times more fluoride than adults do on a per-body-weight basis. Compared to adults, children are more likely to swallow toothpaste and mouth rinses or use more of the product than directed.

Stay Safe

Take an inventory of your fluoride intake from drinking water, food and beverages, and dental care. For more information on how to prevent cavities without getting too much fluoride, see these tips from the CDC. Make sure that children spit out their toothpaste and rinse with water after brushing.

The EPA is in the process of revising the federal MCL, but in the meantime you can find your water’s fluoride level listed in your water utility's Consumer Confidence Report, which must be sent to you annually. If you no longer have a copy, check your water company’s web site or see EPA’s Drinking Water Quality Reports. You can also check the Centers for Disease Control and Prevention (CDC)’s My Water’s Fluoride (MWF) website. If your water comes from a well, consider having it professionally tested. To reduce fluoride in your water, choose a water treatment system that uses distillation or reverse-osmosis. Counter-top carbon-based systems do not remove fluoride.

If your water is fluoridated by your water company, the amount of fluoride must comply with guidelines from the US Department of Health and Human Services (HHS). The department plans to lower the level from 1.2 milligrams per liter to 0.7 milligrams per liter in Spring 2011.

Formula-fed babies may ingest more fluoride than is safe, especially if powdered or liquid concentrate formula is reconstituted with water with levels of fluoride above 1 milligram per liter and if formula is the baby’s main source of nutrition, according to an October 2009 study in the Journal of the American Dental Association. If you are formula-feeding your baby, look for fluoride-free bottled water or water that has been demineralized, deionized, distilled, or reverse-osmosis filtered. Ready-to-feed formulas have safe levels of fluoride, according to the study. Breast feeding is healthier than formula for both babies and mothers, and breast milk does not contain significant amounts of fluoride.

Learn More

Committee on Fluoride in Drinking Water, National Research Council. Fluoride in Drinking Water: A Scientific Review of EPA's Standards. 2006

US. Department of Health and Human Services. News Release. HHS and EPA announce new scientific assessments and actions on fluoride. January 7, 2011

last revised 12/27/2011

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