Fluoride

Promoters of water fluoridation offer the lure of strong, healthy teeth and reduced dental bills as inducements for communities to fluoridate their water. Fluoride is also promoted for other tooth-related uses. However, even the promoters have scaled down the benefits claimed for water fluoridation and admitted the danger of fluorosis from toothpaste. For every study by promoters over recent years repeating old messages that claim undisputed water fluoridation benefits—particularly reduction of cavities, there are equally reputable studies showing little or no effect on cavity rates. Studies in mainstream peer-reviewed medical journals and government reports now document the fact that serious harms are associated with exposure to small amounts of fluoride—including hip fracture, cancer, and intellectual impairment.

“The purpose of this study was to investigate the relationships between caries experience and dental fluorosis at different fluoride concentrations in drinking water. The impact of other fluoride products also was assessed.

Methods: This study used data from the 1986–87 National Survey of US Schoolchildren. Fluoride levels of school water were used as an indicator of the children’s water fluoride exposure. The use of fluoride drops, tablets, professional fluoride treatments, and school fluoride rinses were ascertained from caregiver questionnaires. Only children with a single continuous residence (n=18,755) were included in this analysis.

Results: The sharpest declines in dfs and DMFS were associated with increases in water fluoride levels between 0 and 0.7 ppm F, with little additional decline between 0.7 and 1.2 ppm F. Fluorosis prevalence was 13.5 percent, 21.7 percent, 29.9 percent, and 41.4 percent for children who consumed <0.3, 0.3 to <0.7, 0.7 to 1.2, and >1.2 ppm F water. In addition to fluoridated water, the use of fluoride supplements was associated with both lower caries and increased fluorosis.

Conclusion: A suitable trade-off between caries and fluorosis appears to occur around 0.7 ppm F. Data from this study suggest that a reconsideration of the policies concerning the most appropriate concentrations for water fluoridation might be appropriate for the United States. “

In the first part of our review, biochemical aspects of the biomedicinal chemisty of fluorinated compounds will be covered.  Medicinal aspects of this field are then discussed, with emphasis on drugs that have been recently marketed, or are in the final phases of testing.

“Fluoride (F) is known to affect mineralizing tissues, but effects upon the developing brain have not been previously considered. This study in Sprague-Dawley rats compares behavior, body weight, plasma and brain F levels after sodium fluoride (NaF) exposures during late gestation, at weaning or in adults. For prenatal exposures, dams received injections (SC) of 0.13 mg/kg NaF or saline on gestational days 14–18 or 17–19. Weanlings received drinking water containing 0, 75, 100, or 125 ppm F for 6 or 20 weeks, and 3 month-old adults received water containing 100 ppm F for 6 weeks. Behavior was tested in a computer pattern recognition system that classified acts in a novel environment and quantified act initiations, total times and time structures. Fluoride exposures caused sex- and dose-specific behavioral deficits with a common pattern. Males were most sensitive to prenatal day 17–19 exposure, whereas females were more sensitive to weanling and adult exposures. After fluoride ingestion, the severity of the effect on behavior increased directly with plasma F levels and F concentrations in specific brain regions. Such association is important considering that plasma levels in this rat model (0.059 to 0.640 ppm F) are similar to those reported in humans exposed to high levels of Fluoride. “

“Concerns about dental fluorosis and the paucity of detailed fluoride intake data prompted this longitudinal study of fluoride intake in infants from birth to 9 months of age. On average, water fluoride intake greatly exceeded that from dietary fluoride supplements or fluoride dentifrice. However, fluoride supplements and dentifrice contributed substantial proportions of fluoride intake among children using them. Some children had estimated fluoride intake from water, supplements and dentifrice that exceeded the recommended “optimal” intake (a level that has yet to be determined scientifically). Practitioners should estimate fluoride ingestion from all these sources if considering systemic fluoride supplementation. “

A review of literature and documentation suggests that concentrations of fluoride above 0.2 mg/L have lethal (LC50) effects on and inhibit migration of “endangered” salmon species whose stocks are now in serious decline in the US Northwest and British Columbia. Fluoride added to drinking water,”to improve dental health”, enters the fresh water eco-system, in various ways, at levels above 0.2 mg/L. This factor, if considered in “critical habitat” decisions, should lead to the development of a strategy calling for a ban on fluoridation and rapid sunsetting of the practice of disposal of industrial fluoride waste into fresh water.

Glass ionomer cements reportedly bond to tooth surfaces by physicochemical interaction and slowly release fluoride. 1 Two mechanisms are involved in fluoride release, a rapid surface elution and a slower bulk diffusion of fluoride ions. 2, 3 The greatest release of fluoride reportedly occurs in the first 24 hr, and then remains constant for several months before it tapers off after 2 years.4, 5 Such slow release of fluoride from silicate cements has been shown to have an anticariogenic effect.6, 7 dependent primarily on the longevity of the release.8 Recent research also has reported an antimicrobial effect of glass ionomer cements in vitro 9 and in vivo.10, 11 The objectives of our in vitro experiments were to determine the fluoride and acid release of several glass ionomer cements over time, and the relationship of the fluoride and acid to the antibacterial effects of these cements. (Pediatr Dent 16: 1994)

The death of a 41-year-old male and the illness of approximately 296 others on May 21-23, 1992, in Hooper Bay Alaska has been shown to be due to acute fluoride intoxication caused by malfunction of the fluoridation equipment of system 1 of the village’s two-system (well) water supply. Fluoride levels were reported to be as high as 150 ppm.

BACKGROUND:

Acute fluoride poisoning produces a clinical syndrome characterized by nausea, vomiting, diarrhea, abdominal pain, and paresthesias. In May 1992, excess fluoride in one of two public water systems serving a village in Alaska caused an outbreak of acute fluoride poisoning.

METHODS:

We surveyed residents, measured their urinary fluoride concentrations, and analyzed their serum-chemistry profiles. A case of fluoride poisoning was defined as an illness consisting of nausea, vomiting, diarrhea, abdominal pain, or numbness or tingling of the face or extremities that began between May 21 and 23.

RESULTS:

Among 47 residents studied who drank water obtained on May 21, 22, or 23 from the implicated well, 43 (91 percent) had an illness that met the case definition, as compared with only 6 of 21 residents (29 percent) who drank water obtained from the implicated well at other times and 2 of 94 residents (2 percent) served by the other water system. We estimated that 296 people were poisoned; 1 person died. Four to five days after the outbreak, 10 of the 25 case patients who were tested, but none of the 15 control subjects, had elevated urinary fluoride concentrations. The case patients had elevated serum fluoride concentrations and other abnormalities consistent with fluoride poisoning, such as elevated serum lactate dehydrogenase and aspartate aminotransferase concentrations. The fluoride concentration of a water sample from the implicated well was 150 mg per liter, and that of a sample from the other system was 1.1 mg per liter. Failure to monitor and respond appropriately to elevated fluoride concentrations, an unreliable control system, and a mechanism that allowed fluoride concentrate to enter the well led to this outbreak.

CONCLUSIONS:

Inspection of public water systems and monitoring of fluoride concentrations are needed to prevent outbreaks of fluoride poisoning.

Since our interim report of July 29, 1992, the Section of Epidemiology, Alaska. Department of Environmental Conservation (DEC), and United States Public Health Service (USPHS), have completed the investigation of the outbreak of fluoride poisoning in Hooper Bay.