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Fluoridation of Public Water Supplies
Observational studies by Dean and colleagues during the 1930s identified reductions in dental caries at a naturally occurring fluoride concentration of 1 mg per liter.[3,4] This level of fluoride resulted in decreased caries prevalence without objectionable levels of dental fluorosis, prompting the adoption of this concentration as an optimal level. In 1993, the National Research Council  concluded that there was not sufficient evidence to support changing the upper limit of 1.2 parts per million (ppm) of fluoride in drinking water. More recently, the U.S. Public Health Service reviewed this drinking water standard and reaffirmed optimal levels of 0.7 to 1.2 ppm fluoride (dependent on annual average of maximum daily air temperatures) to yield an average of 1 mg per day of consumed fluoride. Where the fluoride content of drinking water is naturally increased, the Environmental Protection Agency recommends reductions to a level of 2.0 ppm. Water sources with fluoride levels of 0.0 to 0.3 ppm are considered to be non-fluoridated.
The Healthy People 2000 document  contains reference to the issue of fluoride as it relates to health of the American public. Specific objectives relevant to fluoridation include:
|objective 13.9||Increase to at least 75 percent the proportion of people served by community water systems providing optimal levels of fluoride. (baseline: 62 percent in 1989)|
|objective 13.10||Increase use of professionally or self-administered topical or systemic (dietary) fluorides to at least 85 percent of people not receiving optimally fluoridated public water. (baseline: 50 percent in 1989)|
The reported benefits and risks associated with exposure to fluoride are highlighted in the following sections.
Comparable decreases in caries prevalence have also been observed in communities in non-fluoridated areas. Suggested reasons for this include greater use of fluoride-containing dental care products, reductions in the consumption of refined sugar, better access to and utilization of dental health services, improvements in oral hygiene and increased awareness of dental health.[10,11,12]
While the majority of published studies have examined dental health among adolescents, dental decay is also common during the later years of life in the form of root surface caries. Fewer carious lesions have been identified among older persons residing in communities with optimal fluoride levels. [13,14]
Several factors may be operative in observed temporal declines in caries prevalence including improved access to dental care, enhanced knowledge of dental hygiene, expanded use of fluoride-containing dental care products and increased exposures to fluoride through foods and beverages. Overall, the preponderance of evidence indicates that fluoride is beneficial to dental health.
The action of fluoride on teeth involves both topical and systemic mechanisms. Fluoride acts to stabilize the hydroxyapatite matrix on internal and external tooth surfaces.[15,16] Topical application of fluoride has been shown to decrease levels of dental plaque bacteria. Systemic fluoride is provided by fluoridated public water supplies, dietary supplements, foods, and beverages. Sources of topical fluorides include fluoride-containing dentifrices, mouth rinses, and gels.
Dental caries is a health problem which impacts on the medical, functional, nutritional and psychological status of patients in all age groups. The prevalence of dental caries is 42% at five years of age, increasing to more than 84% by age 17.[18,19,20,21] The Health Care Financing Administration estimates that 5% of the total health care expenditures (or $34 billion dollars) is spent on dental services of which 13.2% (or $4.5 billion) is used for amalgam restoration.
Other Potential Benefits
While excessive chronic fluoride exposure may result in skeletal fluorosis, this manifestation is extremely rare with only a handful of cases reported during the past 30 years. A study of persons exposed to drinking water sources with >4 mg/liter (e.g., >4 ppm) of fluoride showed no evidence of radiographic change.
Previous reports which compared cancer mortality [30,31,32,33,34,35) in fluoridated and non-fluoridated areas revealed no association with fluoride levels in drinking water. Similarly, studies of cancer incidence in fluoridated and non-fluoridated communities identified no significant differences.[30,36] An additional study of persons occupationally exposed to fluoride reported elevated incidence for cancers of the respiratory tract, most likely resultant from smoking habits rather than fluoride exposure.
Other Potential Risks
Further information on the reported risks and benefits of fluoride exposure is available in primary sources as well as comprehensive review papers on this topic. [42,43]
The American Academy of Pediatrics (AAP) has issued a schedule for fluoride supplementation  (see Table 1). These recommendations take account of the levels of fluoride contained in the primary drinking water supply as well as the age of the pediatric patient. Changes in the current AAP schedule include the elimination of fluoride supplementation during the first six months, decreased doses of supplemental fluoride from age six months to six years, and decreasing the level at which no supplementation is needed from 0.7 ppm to 0.6 ppm. Dietary supplementation among children in fluoride-deficient communities is also supported by the U.S. Preventive Services Task Force.
The magnitude of scale which exists between typical exposures and exposures likely to result in untoward health effects refers to the term "margin of safety." It is important to recognize that a relatively narrow margin of safety may exist for development of dental fluorosis among children consuming fluoridated drinking water or consuming fluoride supplements. Patients should be cautioned about the toxicity of fluoride when it is prescribed in tablet or liquid form. Parents should monitor their children's use of dentifrices and other dental products that may represent sources of excessive fluoride ingestion. Physicians should be aware of the fluoride levels in water supplies, as well as possible sources of regional environmental fluoride contamination, so as to appropriately prescribe supplements.
To minimize the risk of systemic ingestion of topical fluoride agents children should be supervised when using products containing fluoride. Toothpaste contains fluoride at a level of 1 mg /gram, thus unsupervised children can ingest excessive fluoride. For example, a two-year old, brushing his/her teeth twice a day, could ingest as much as 0.5 mg a day.
Dental caries represents a health problem which impacts on the medical, functional, nutritional, and psychological status of patients. Fluoridation of public water supplies is a safe, economical, and effective measure to prevent dental caries. When drinking water levels of fluoride are suboptimal, dietary supplementation should be considered. (1996) (2002) (2008)
|Child's Age||Fluoride content of drinking water (in parts per million [ppm])|
|birth to six months||0 mg||0 mg||0 mg|
|six months - 3 years||0.25 mg||0 mg||0 mg|
|3 - 6 years||0.50 mg||0.25 mg||0 mg|
|6 - 16 years||1.00 mg||0.50 mg||0 mg|
Source: American Academy of Pediatrics, Committee on Nutrition. Fluoride supplementation for children:
- Public Health Service. Healthy People 2000: national health promotion and disease prevention objectives. DHHS publication no. (PHS) 91-50212. U.S. Government Printing Office, Washington, DC, 1990.
- Levy SM, Kiritsy MC, Warren JJ. Sources of fluoride intake in children. Journal Public Health Dentistry 1995; 55: 39-52.
- Dean HT. Endemic fluorosis and its relation to dental caries. Public Health Reports 1938; 53: 1443-1446.
- Dean HT, Arnold FA, Elvone E. Domestic water and dental caries. V. Additional studies of the relation of fluoride domestic waters to dental caries experience in 4425 white children aged 12 to 14 years of 13 cities in 4 states. Public Health Reports 1942; 57: 1155-1179.
- National Research Council, Committee on Toxicology. Health effects of ingested fluoride. Washington, DC: National Academy Press, 1993.
- Centers for Disease Control and Prevention. Engineering and administrative recommendations for water fluoridation, 1995. MMWR; 44(No. RR-13): 1-40.
- Murray JJ and Rugg-Gunn AJ. Fluorides in caries prevention, 2nd edition. Derrick DD, ed., Wright-PSG, Boston, 1982.
- Lemke CW, Doherty JM and Arra MC. Controlled fluoridation: the dental effects of discontinuities in Antigo, Wisconsin. Journal American Dental Association. 1970; 80: 782-786.
- Attwood D and Blinkhorn AS. Trends in dental health of 10-year-old school children in southwest Scotland after cessation of water fluoridation. Lancet 1988; 2: 266-267.
- Diesendorf M. The mystery of declining tooth decay. Nature 1986; 322: 125-129.
- DePaola PF, Soparkar PM, Tavares M, Allukian M, Peterson H. A dental survey of Massachusetts schoolchildren. Journal of Dental Research 1982; 61: 1356.
- Weatherell JA, Robinson C, Strong. Future possibilities for increased tooth resistance to dental caries. Canadian Dental Association Journal 1984; 50: 149-156.
- Stamm JW, Banting DW. Comparison of root-caries prevalence in adults with lifelong residence in fluoridated and non-fluoridated areas. Journal of Dental Research 1980; 59: 405.
- Burt BA, Ismail LI, Elkund SA. Root caries in an optimally fluoridated and a high-fluoride community. Journal of Dental Research 1986; 65: 1154-1158.
- Levine RS. The action of fluoride in caries prevention: a review of current concepts. British Dental Journal 1976; 140: 9-14.
- Levine RS. The aetiology of dental caries -- an outline of current thought. International Dental Journal 1977; 27: 341-348.
- Newbrun E. Fluorides and dental caries, 3rd ed., Charles C. Thomas, Springfield, IL, 1986.
- National Institute of Dental Research. Oral health of United States children: the National Survey of Dental Caries in U.S. school children: 1986-87; national and regional findings. DHHS publication no. (PHS) 89-2247, 1989.
- Newbrun E. Effectiveness of water fluoridation. Journal of Public Health Dentistry 1989; 49: 279-289.
- Centers for Disease Control. Public health focus: fluoridation of community water supplies. MMWR 1992; 41: 372, 375-381.
- Edelstein BL, Douglass CW. Dispelling the myth that 50 percent of U.S. schoolchildren have never had a cavity. Public Health Reports 1995; 110: 522-530.
- Phipps K. Fluoride and bone health. Journal of Public Health Dentistry 1995; 55: 53-56.
- Heifetz SB, Horowitz HS. Amounts of fluoride in current fluoride therapies: safety considerations for children. ASDC Journal of Dentistry for Children 1984; 51: 257-269.
- Whitford GM. Fluoride in dental products: safety considerations. Journal of Dental Research 1987; 66: 1056-1060.
- Duxbury AJ, Leach FN, Duxbury JT. Acute fluoride toxicity. British Dental Journal 1982; 153: 64-66.
- Stevenson CA, Watson AR. Fluoride osteosclerosis. American Journal of Roentgenology 1957; 78: 15-18.
- Toxicology and carcinogenesis studies of sodium fluoride (CAS no. 7681-49-4) in F344/N rats and B6C3F1 mice (drinking water studies). Research Triangle Park, NC: National Toxicology Program; 1990. Technical Report Series no. 393. NIH publication 91-2848.
- Mahoney MC, Nasca PC, Burnett WS, Melius JM. Bone cancer incidence rates in New York State: time trends and fluoridated drinking water supplies. American Journal of Public Health 1991; 81: 475-479.
- Gelberg KH, Fitzgerald EF, Hwang S, Dubrow R. Fluoride exposure and childhood osteosarcoma: a case-control study. American Journal of Public Health 1995; 85: 1678-1683.
- Hoover RH, McKay FW, Fraumeni JF: Fluoridated drinking water and the occurrence of cancer. JNCI 1976; 57; 757-768.
- Clemmesen J. The alleged association between artificial fluoridation of water supplies and cancer. Bulletin of the World Health Organization 1983; 61: 871-883.
- Cook-Mozaffari P, Doll R. Fluoridation of water supplies and cancer mortality II: mortality trends after fluoridation. Journal of Epidemiology and Community Health 1981; 35: 233-238.
- Griffith GW. Fluoridation and cancer mortality in Anglesey. Journal of Epidemiology and Community Health 1985; 39: 224-226.
- Chilvers C, Conway D. Cancer mortality in England in relation to levels of naturally occurring fluoride in water supplies. Journal of Epidemiology and Community Health 1985; 39: 44-47.
- International Agency for Research on Cancer: some aromatic amines, anthraquinones and nitroso- compounds, and inorganic fluorides used in drinking water and dental preparations. Lyon: World Health Organization, International Agency for Research on Cancer, 1982, volume 27.
- Kinlen L. Cancer incidence in relation to fluoride levels in water supplies. British Dental Journal 1975; 138: 221-224.
- Grandjean P, Juel K, Jenson OM. Mortality and cancer morbidity after heavy occupational fluoride exposure. American Journal of Epidemiology 1985; 121: 57-64.
- Danielson C, Lyon JL, Egger M, Goodenough GK. Hip fractures and fluoridation in Utah's elderly population. JAMA 1992; 268: 746-748.
- Simoen O, Laitinen O. Does fluoridation of drinking-water prevent bone fragility and osteoporosis? Lancet 1985; 2: 432-434.
- Cooper C, Wickham C, Lacey RD, Barker DW. Water fluoride concentration and fracture of the proximal femur. Journal of Epidemiology and Community Health 1990; 44: 17-19.
- Cooper C, Wickham CAC, Lacey RJD, Jacobsen SJ. Water fluoridation and hip fracture. JAMA 1991; 266: 513-514.
- Kaminsky LS, Mahoney MC, Leach J, Melius J, Miller MJ. Fluoride: Benefits and risks of exposure. CRC Critical Reviews in Oral Biology and Medicine 1990; 1: 261-281.
- Review of fluoride. Benefits and risks. Report of the ad hoc subcommittee on fluoride of the committee to coordinate environmental health and related programs. Washington, DC: US Department of Health and Human Services, 1991.
- American Academy of Pediatrics, Committee on Nutrition. Fluoride supplementation for children: interim policy recommendations. Pediatrics 1995; 95: 777.
- U.S. Preventive Services Task Force. Guide to clinical preventive services, 2nd ed., Baltimore: Williams & Wilkins, 1996.