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9) Fluoridated Water for Adults: Very Little, If Any, Benefit

Historically, most of the research on whether water fluoridation has a benefit, has been focused on children. By way of contrast, only a small handful of studies have ever examined the effectiveness of fluoridated water for adults.  According to a 2001 review by the Ontario Ministry of Health and Long Term Care (Locker 2001), "The absence of adults from water fluoridation studies is difficult to explain... Whatever the reason, it must be regarded as a major limitation in the research effort to date."

In 2007, an important study was published which sheds light on whether fluoridated water is effective at preventing tooth decay in adult populations (9a). Despite a recent press release to the contrary, the study indicates very little, if any, benefit.

To assess fluoridation’s effectiveness, the study examined the dental treatment costs accrued over 5 years by 51,683 members from an HMO. The HMO members, including both adults and children, lived in fluoridated and non-fluoridated communities of 3 separate regions in the Northwest. The authors, a team of pro-fluoridation researchers, state that the study shows a "small" benefit from fluoridated water which "may" have led to some cost-savings. A close inspection of their data, however, shows that this "small benefit” -- if it even exists -- was very small indeed.

For example, in the largest region examined in the study, representing over 75% of the HMO members surveyed (the Portland metro area of Oregon), fewer children and adults in the non-fluoridated areas required treatment than children and adults in the fluoridated areas. Moreover, the children and adults in the non-fluoridated area who sought treatment accrued lower total costs over the 5-year period than those in the fluoridated area. As noted by the authors, the “Portland metro had lower treatment costs for the NF (Non-Fluoridated) area...”

These findings from the Portland region are remarkable: after all, one of the most-frequently cited claims by fluoridation proponents is that every $1 spent on fluoridated water saves $80 in dental bills. In this study, the dental care costs in the largest region surveyed were lower in the areas without water fluoridation.

Even among the the smaller regions in the study (Marion County, Oregon and Clark County, Washington), which produced more favorable results for the fluoridated areas, the results were still inconsistent and the benefits marginal. As the authors admit, "the effect we observed was generally small."

One of the reasons given by the authors for why the benefit was small and inconsistent was that the population being studied was insured and had ready access to dental care and preventive procedures. However, a separate study by a University of Michigan research team suggests that water fluoridation is equally ineffective in low-income areas as well (9b). The study examined a group of 800 low-income African American adults living in Detroit. Despite the fact that Detroit has been fluoridated since 1967, the authors found that tooth decay was "severe" and "extensive", with tooth decay rates reaching as high as 99.8% for individuals aged 14 to 35 years.

What makes this Detroit study particularly interesting, is that -- unlike the vast majority of studies investigating fluoridation’s effectiveness -- the authors actually assessed the quantity of fluoridated tap water consumed by each individual. When they then compared the quantity of fluoridated water consumed with the rate of tooth decay, they found no relationship. In other words, ingestion of fluoridated tap water for up to 4 decades did nothing to produce better teeth in this disadvantaged population.

NEXT: Second Thoughts on Water Fluoridation

REFERENCES:

9a) Maupomé G, et al. (2007). A comparison of dental treatment utilization and costs by HMO members living in fluoridated and nonfluoridated areas. Journal of Public Health Dentistry 67(4):224-33.

9b) Burt BA, et al. (2006). Dietary patterns related to caries in a low-income adult population. Caries Research 40(6):473-80.

See also: Top 10 Scientific Developments of 2006