Nebraska Cooperative Extension G98-1376-A

A University of Nebraska NebGuide Publication

Drinking Water: Fluoride

This NebGuide discusses fluoride in domestic water supplies.


Sharon Skipton, Extension Educator
DeLynn Hay, Extension Water Resources Specialist

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Fluoride in Drinking Water

Fluoride, a naturally occurring element, exists in combination with other elements as a fluoride compound and is found as a constituent of minerals in rocks and soil. When water passes through and over the soil and rock formations containing fluoride it dissolves these compounds, resulting in the small amounts of soluble fluoride present in virtually all water sources.

A study of fluoride in Nebraska's groundwater reported a range of concentrations from less than 0.1 milligrams per liter (mg/l) to 2.6 mg/l with an average of 0.3 mg/l (Headrick, 1996). Three areas in Nebraska, the Upper Republican River Valley, Knox County, and the Panhandle had average concentrations higher than 0.6 mg/l or had average concentrations near 0.6 mg/l with a significant percent of samples over 1.5 mg/l. Counties included in each area, and the average fluoride concentration for each according to a Nebraska Health and Human Services System database used in the Headrick study, were: (see Figure 1) the Republican River Valley Area — Chase (0.8 mg/l), Dundy (1.0 mg/l), Hayes (0.8 mg/l), Hitchcock (0.9 mg/l), Red Willow (0.6 mg/l) and Frontier (0.7 mg/l); Knox County (0.5 mg/l with 32 percent of samples having concentrations greater than 1.5 mg/l); and the Panhandle Area — Box Butte (0.8 mg/l), Kimball (0.6 mg/l), Cheyenne (0.7 mg/l) and Scotts Bluff (0.5 mg/l). Scotts Bluff county, with an average concentration below 0.6 mg/l, was included because a USGS database also used by Headrick showed it had an average fluoride concentration of 0.8 mg/l. Fluoride concentrations reported in the two databases agreed within 0.1 mg/l for all other counties.

Figure 1. Counties with average groundwater flouride concentration (milligrams per liter) greater than 0.5 mg/l.

The Nebraska Health and Human Services System Department of Dental Health recommends a fluoride concentration of 0.7 to 1.5 mg/l in drinking water to prevent tooth decay. The Centers for Disease Control recommends a fluoride concentration of 1 mg/l as the optimum level to prevent tooth decay. Recommended fluoride levels in drinking water are discussed in the "Interpreting Test Results" section of this publication. The Department reports Nebraska communities with natural fluoride levels of 0.7 mg/l and above in their water include (see Figure 2) Abie, Alliance, Bartley, Benkelman, Bushnell, Cambridge, Clarks, Craig, Crawford, Culbertson, Elk Creek, Gurley, Haigler, Hayes Center, Hemingford, Henry, Imperial, Indianola, Jackson, Lebanon, Lyman, Memphis, Morrill, Nehawka, Oakland, Oshkosh, Palisade, Stratton, Trenton, Uehling, Verdel, Walthill, Wauneta and Winnebago.

Figure 2. Nebraska communities with natural flouride drinking water concentrations of 0.7 milligrams per liter or above.

In some communities, fluoride is added to public water supplies; a process known as fluoridation. Water fluoridation involves adjusting the natural level of fluoride to the levels recommended to prevent tooth decay. There is no difference in potential health effects between naturally occurring fluoride or that added through fluoridation.

In the summer of 1998, the Nebraska Health and Human Services System Department of Dental Health reported that the following Nebraska communities or rural water districts throughout Nebraska fluoridate their public water supply: Albion, Allen, Auburn, Bassett, Blair, Bloomfield, Blue Hill, Cedar-Knox Rural Water District, Colridge, Columbus, Cook, Creighton, Crofton, Elgin, Elmwood, Emerson, Falls City, Fairbury, Fremont Fullerton, Gering, Gordon, Grand Island, Hallam, Hartington, Hickman, Holdrege, Humphrey, Kearney, Laurel, Lincoln, Lindsay, Louisville, Lyons, Macy, Magnet, Minden, Nebraska City, Neligh, Nelson, O'Neill, Ogallala, Omaha, Osmond, Papillion, Plattsmouth, Red Cloud, Rushville, Scribner, Shelby, South Sioux City, Springfield, Stanton, Stella, Superior, Syracuse, Tecumseh, Tilden, Utica, Valley, Valparasio, Wausa, Wayne and West Point. Adams, Ruskin and Waverly are installing fluoridation equipment and expected to fluoridate by fall, 1998. Approximately 70 percent of Nebraskans served by a public water system receive fluoridated water.

Fluoridation of drinking water can be controversial. Opponents argue fluoridation violates individual rights and goes against religious beliefs that ban medication. The courts have established fluoridation is not an unconstitutional invasion of religious freedom or other individual rights guaranteed by the First, Fifth or Fourteenth Amendments to the U.S. Constitution. It has been the position of courts that a significant government interest in health and welfare of the public generally overrides individual objections to public health regulation.

Opponents also argue that drinking fluoridated water promotes a variety of physical and mental ailments including sickle-cell anemia, cancer, cardiovascular disease, AIDS, Down Syndrome and Alzheimer's disease. Since the 1930's, many scientific studies have shown that water fluoridation, at the concentrations recommended for good oral health, has no harmful effects. A 1992 policy statement on water fluoridation by the Surgeon General of the U.S. Public Health Service and the Assistant Secretary of Health recommended fluoridation of community water supplies be continued in areas where naturally occurring fluoride levels are deficient.

Fluoridation is endorsed by both the American Dental Association and the American Medical Association, as well as numerous national and international organizations including the American Academy of Pediatrics, American Academy of Pediatric Dentistry, American Pharmaceutical Association, American Society of Dentistry for Children, Mayo Clinic, National Academy of Sciences, National Cancer Institute, National Health Council and U.S. Public Health Service Centers for Disease Control and Prevention, Food and Drug Administration and National Institute of Health.

Indications of Fluoride

Fluoride in drinking water cannot be detected by taste, sight or smell. Testing is the only way to determine the fluoride concentration.

Potential Health Effects

The dental benefits from consuming water containing optimum levels of fluoride are well-documented. The Nebraska Health and Human Services System Division of Dental Health indicates that 0.7 to 1.5 milligrams per liter of fluoride in drinking water protects against tooth decay, reducing the incidence of dental caries (tooth decay), as well as aiding bone and tooth development. The American Dental Association has stated that fluoride benefits people of all ages. When children are young and their teeth are still forming, fluoride makes tooth enamel harder and more resistant to decay-causing acid. Studies indicate that people who drink optimally fluoridated water from birth will experience up to 40 percent less decay over their lifetimes. For adults, fluoride helps repair the early stages of tooth decay even before it becomes visible, a process known as remineralization. For older adults, fluoride has been effective in decreasing problems with root caries (decay along the gumline).

Although low levels of fluoride are beneficial, excessive amounts can be harmful. Excessive fluoride in drinking water may produce fluorosis (mottling of teeth), which increases as the optimum level of fluoride is exceeded. Dental fluorosis appears during tooth formation and is caused by excessive fluoride ingestion, which leads to enamel protein retention, hypomineralization of the dental enamel and dentin and disruption of crystal formation. The effects range from barely perceptible white striations or specks on teeth to severe pitting and/or permanent brown to brownish gray stains on teeth. Continued consumption of water containing more than 2 mg/l fluoride will likely produce mild to moderate dental fluorosis. Continued consumption of water containing increasingly higher concentrations of fluoride will generally produce more severe dental fluorosis. However, according to the American Academy of Pediatrics, the effect of fluorosis is only cosmetic. Teeth affected by fluorosis seem to be resistant to dental caries.

Like other trace elements, excessive quantities of fluoride can result in acute or chronic toxicity. Consumption of an excessive amount of fluoride (300 to 750 milligrams depending on body weight) in a single dose can cause acute toxicity resulting in nausea or vomiting. This level of fluoride intake would only occur as a result of some type of accidental event, such as small children consuming an overdose of fluoride supplements. At the optimum fluoridation level of 1 mg/l, it would take ingesting 80 to 200 gallons of water to reach the acute toxicity level, an amount impossible to drink at any one time.

The National Academy of Sciences has studied the possibility of adverse health effects from continuous consumption of fluoride over long periods of time. The Academy reported daily intake required to produce chronic toxicity after years of consumption, is 20 to 80 milligrams or more per day depending upon body weight. This level of fluoride intake has been associated with water supplies containing at least 10 mg/l of natural fluoride, as in parts of India and where water consumption was high because of extreme climatic conditions. (U.S. Public Health Service Report of the Ad Hoc Subcommittee to Coordinate Environmental Health and Related Programs, 1991; and National Research Council Report of the Subcommittee on Health Effects of Ingested Fluoride, 1993.) For information on possible health effects from chronic fluoride toxicity, consult your physician.

Water supplies almost never reach fluoride levels capable of producing acute or chronic health effects naturally and never reach them when EPA primary and secondary fluoridation standards are followed. System surveillance is important to guarantee EPA standards are followed in a fluoridated water system. Nebraska water supplies have never been documented with fluoride levels capable of producing an immediate health risk.

This publication does not substitute for professional medical advice. If you have any questions or concerns related to potential health effects from consuming fluoridated water, consult your physician.

Fluoride is present to some extent in all foods and beverages, and in many oral care products, such as toothpastes, mouth rinses and gels. Consult your physician/dentist to develop a dental care plan that assures optimal fluoride exposure from water, food, topical treatment, and supplements.

Testing

Public water supplies must be tested for fluoride concentration. If your water comes from a public water supply, contact your water supplier to find out the fluoride level. The water supplier can also tell you if the fluoride occurs naturally or is added by fluoridation. Public water suppliers must notify water users if the fluoride level exceeds the Secondary Maximum Contaminant Level of 2.0 mg/l (See the "Interpreting Test Results" section).

If you want to know the fluoride concentration in a private water supply, you must have the water tested. These tests should be done by a laboratory approved for fluoride testing of public water supplies. In Nebraska, such approval comes from the Nebraska Health and Human Services System Department of Regulation and Licensure. This approval means recognized, standard test and quality control procedures are used. For a list of approved water testing laboratories in Nebraska, see NebGuide 89-907, Testing for Drinking Water Quality. Carefully follow all directions provided by the laboratory and use containers provided by the laboratory when collecting water samples.

Interpreting Test Results

Water supplied by Public Water Systems is regulated by the U.S. Environmental Protection Agency (EPA) and the Nebraska Health and Human Services System Department of Regulation and Licensure. Individual private wells are not required to meet drinking water standards.

Drinking water standards established by EPA fall into two categories – Primary and Secondary Standards. Primary Standards are based on health considerations and are designed to protect human health. Secondary Standards are based on aesthetic factors such as taste, odor, color, corrosivity, foaming and staining properties of water that may affect water's suitability for drinking and other domestic uses. Water with a contaminant at or below the Primary Standard is acceptable for drinking every day over a lifetime and does not pose a health risk.

The Secondary Maximum Contaminant Level (SMCL) for fluoride is 2 milligrams per liter (mg/l) which is equal to 2 parts per million (ppm). Water with a fluoride concentration at or below 2 mg/l does not present a health risk and should not cause fluorosis. The Primary Maximum Contaminant Level (MCL) for fluoride in drinking water is 4 mg/l. Daily consumption of water with a fluoride concentration at or below 4 mg/l does not present a health risk, but could cause fluorosis if the level exceeds the SMCL of 2 mg/l. Fluorosis is not considered a health risk but does have an aesthetic impact on teeth. See the Potential Health Effects Section of this publication for more information on fluorosis.

Options

If naturally occurring fluoride exceeds optimum levels, or if the presence of fluoride in drinking water through fluoridation is not desired, consider water treatment or an alternative drinking water source, such as bottled water.

There are four treatment methods suitable for removing fluoride from drinking water, including activated alumina filters, distillation, reverse osmosis and anion exchange. Typically, these methods are used to treat water only at one faucet. Treatment units can furnish an adequate supply of defluoridated drinking and cooking water for the home. Work with a reliable, competent water treatment dealer to select the treatment method best for your situation. If treatment is selected to reduce fluoride levels exceeding optimum levels, the treatment will probably remove nearly all of the fluoride from the water. Treating water to remove or reduce other contaminants such as nitrate also may remove nearly all fluoride from the water. In these cases it may be necessary to use fluoride supplements, generally obtained by prescription from a doctor/dentist, for beneficial use.

Summary

All water contains naturally occurring fluoride. Fluoride is also added to some public drinking water supplies; a process known as fluoridation. At the optimum level of 1 mg/l, fluoride reduces the occurrence of dental decay. Elevated levels of fluoride in drinking water can cause fluorosis, or mottling of teeth. High levels, above those typically found in water, consumed over a long period can cause chronic toxicity. Extremely high levels, significantly above those found in water, can cause acute toxicity. Tests by reputable, qualified laboratories can determine the presence and amount of fluoride in drinking water. If fluoride is present above a desirable level, options include using water treatment equipment to remove the fluoride or an alternative water source. If fluoride is removed from water by treatment, and it is desirable to have optimal levels of fluoride for the beneficial effects, it is likely necessary to add fluoride supplements to the daily diet.

Other Related NebGuides

G02-1448, Drinking Water: Bottled or Tap?
G89-907, Testing for Drinking Water Quality
G90-976, Water Treatment Equipment: A Buyer's Guide
G90-989, Drinking Water: Bacteria
G92-1079, Home Water Treatment Equipment: An Overview
G96-1274, Drinking Water: Hard Water
G96-1275, Drinking Water: Sulfates and Hydrogen Sulfide
G96-1279, Drinking Water: Nitrate-Nitrogen
G96-1280, Drinking Water: Iron and Manganese
G96-1282, Drinking Water: Man-made Chemicals
G97-1333, Drinking Water: Lead
G98-1360, Drinking Water: Copper
G98-1369, Drinking Water: Nitrate and Methemoglobinemia ("Blue Baby" Syndrome)

References

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File: G1376 under: WATER RESOURCE MANAGEMENT
A-26, Water Quality, 3,000 printed
Issued January 1999

Electronic version issued April 1999
pubs@unlvm.unl.edu


Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Elbert C. Dickey, Director of Cooperative Extension, University of Nebraska, Institute of Agriculture and Natural Resources.

University of Nebraska Cooperative Extension educational programs abide with the non-discrimination policies of the University of Nebraska-Lincoln and the United States Department of Agriculture.