The researchers from the University of Iowa evaluated the fluoride intake of more than 600 Iowa children from birth to adolescence, carrying out periodic examinations of their dental and bone health. The still-ongoing study paints a picture of fluoride's risks and benefits that doesn't square with claims that public health authorities in Canada and the United States have long peddled.
In 2009, researchers from the Iowa Fluoride Study published the first data on the effect of total fluoride exposure on dental health of children. It was discovered that the intake of fluoride was significantly associated with dental fluorosis, but not with the reduction of dental caries. This was a big disappointment for fluoridation proponents. Indeed, the study demonstrated that there is no relationship between fluoride intake and dental caries. Children without caries ingested substantially the same amount of fluoride in each year of their life, as children with cavities.
According to the authors: “These findings suggest that achieving a caries-free status may have relatively little to do with fluoride intake, while fluorosis is clearly more dependent on fluoride intake.”
To emphasize this point, the following are highlights of three important studies:
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CONSIDERATIONS ON OPTIMAL FLUORIDE INTAKE USING DENTAL FLUOROSIS AND DENTAL CARIES OUTCOMES—A LONGITUDINAL STUDY (1)
The authors recall that “the “optimal” intake of fluoride in children has been widely accepted for decades as between 0.05 and 0.07 mg fluoride per kilogram of body weight (mgF/kg bw), although it is not clear whether this intake is “optimal” for caries prevention, fluorosis prevention, or a combination of both.
The estimates of optimal intake are largely based upon data originally from the 1930s and 1940s, when the market was not yet flooded with fluoridated dental hygiene products and there was a limited understanding of how fluoride works in the prevention of dental caries. At the time, proponents only considered fluoride’s systemic action, not its primarily topical action.
Also, only fluoridated water was relied upon as a source of fluoride. At a concentration of 1.2 ppm, they didn’t worry about the risks of dental fluorosis. A long time had passed in the history of fluoridation before researchers began to establish an “optimal” intake of fluoride in milligrams per kilogram of body weight. This was done without any direct assessment of how this intake is related to the onset or severity of dental caries and/or dental fluorosis.
Today's evidence casts doubt on the safety and benefits of ingested fluoride, because fluoride’s action is primarily topical. There are countless fluoride-containing products available on the market. The quantification of fluoride intake is much more complex than it used to be, making it difficult for researchers to properly quantify the intake of each subject. To believe that parents can compare their child's intake to the recommended level would be utopian. For example, how can one determine the amount of fluoride in toothpaste that a child might swallow while brushing their teeth?
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THE RELATIONSHIPS BETWEEN FLUORIDE INTAKE LEVELS AND FLUOROSIS (2)
In a 2018 follow-up study, the authors found that almost 30% of participants had definitive dental fluorosis at fluoride intake levels considered ‘optimal,’ and that dental fluorosis prevalence is closely related to fluoride intake levels.
