# 12.4: Fluoride

Fluoride is a nonessential mineral. It is not required by the body and it is not widely found in the food supply. The majority of what we consume comes from fluoridated water. Other good non-dietary sources are fluoridated toothpaste and dental rinses1. Absorption of fluoride is near 100% for both dietary and non-dietary forms and it is rapidly excreted in the urine2. Fluoride alters the mineralization of bones and teeth. It does this by replacing hydroxyl (OH) ions in hydroxyapatite ($$\ce{Ca_{10}(PO_4)_6(OH)_2}$$), forming fluorohydroxyapatite. Fluorohydroxyapatite is more resistant to acid degradation than hydroxyapatite, leading to fewer cavities2. Since it is a nonessential mineral, there is no fluoride deficiency. However, fluoride can be quite toxic. Acute toxicity symptoms from large intakes of fluoride include1 nausea, vomiting, diarrhea, and convulsions.

### Fluorosis

Chronic toxicity results in an irreversible condition known as fluorosis, characterized by the mottling and pitting of teeth as shown below.

Figure $$\PageIndex{1}$$: Severe case of fluorosis. Image used with permission (Public Domain; U.S. National Library of Medicine's National Institutes of Health).

As you can see from the figure below, fluorosis is more prevalent in the United States than most people would probably believe.

Figure $$\PageIndex{2}$$: Fluorosis prevalence by age in the United States. Beltran-Aguilar, ED, Barker, L, Dye, BA. (2010) Prevalence and Severity of Dental Fluorosis in the United States, 1999-2004. http://www.cdc.gov/nchs/data/databriefs/db53.htm

A comparison of the prevalence of fluorosis in US children, ages 12-15, indicates an increase from the late 1980s to the early 2000s5.

Figure $$\PageIndex{3}$$: Change in dental fluorosis in 12-15 year-old US children. Beltran-Aguilar, ED, Barker, L, Dye, BA. (2010) Prevalence and Severity of Dental Fluorosis in the United States, 1999-2004. http://www.cdc.gov/nchs/data/databriefs/db53.htm

There is debate as to whether water should be fluoridated. The following links are examples of just how conflicted the U.S. is. The first is a New York Times article on this topic. There is also an article about Portland’s decision to begin fluoridating its water in 2014. The third article is about a bill introduced by a Kansas lawmaker concerned about the effects of water fluoridation. Salina, Kansas, which is home to one of Kansas State University’s campuses, voted last November to not rescind its policy of fluoridating its water, as described in the fourth link.