A common complaint against water fluoridation is that fluoride contributes to bone fractures. Many studies have been completed on this subject, with varying results. In some cases, populations from the same country would show a negative effect while others would report no negative effect whatsoever, and others would demonstrate a positive effect on the number of bone fractures due to drinking fluoridated water. In identifying the reason for these contradictory studies, one group of researchers said this: “[These studies] may be biased by unknown confounding factors.”
What Are Confounding Factors?
Different groups of people, even within the same country, can follow vastly different daily habits. Some may eat a healthy diet, while others subsist on processed foods. One group may exercise vigorously, while another is excessively sedentary. These things are believed to affect the rates of osteoporosis or bone fractures in the elderly. Yet did each of these studies consider such behavioral aspects in their review of water fluoridation and osteoporosis? The facts suggest that they did not. Indeed, it is a difficult thing to include every potential variable in a study that looks for the effect of one thing on another. And it is these “extra variables” that constitute “confounding factors” in scientific experiments.
Reducing Confounding Factors
By reading the evidence submitted with the U.S. Public Health Service’s latest water fluoridation recommendation, it is evident that government scientists have carefully combed the scientific literature for studies that consider the confounding factors. The Journal of Bone and Mineral Research presented one such experiment conducted in China during 2001. Scientists studied six Chinese populations, more than 8,000 people, drinking local water with fluoride concentrations ranging from .25 to 7.97 parts per million (ppm). (Fluoride is found naturally in many bedrock formations and thus makes its way into some public water supplies without any supplementation, and occasionally in very high amounts.) In addition to looking at fluoride concentrations, the researchers also evaluated the effect of smoking, demographics, medical history, physical activity and alcohol consumption on bone fractures. What they discovered is that in these populations, people exposed to approximately 1 ppm of fluoride in their water had the lowest incidence of fractures. Above 4.3 ppm, they noticed an increase in bone fractures. Fall below 1 ppm of fluoride and they again saw a steady increase in the fracture rate.
Interestingly enough, the United States has used municipal water fluoridation in some communities for more than 70 years, and approximately 1 ppm was long the standard for water fluoridation. The current standard, set in 2015, is .7 mg/L (whether milligrams per liter or parts per million, the amount is basically the same). And the maximum standard, used in communities where fluoride must be removed from the local water source due to high levels in the bedrock, is 4 mg/L. It should be reassuring to see additional scientific evidence that demonstrates the significant forethought put into the water fluoridation standards used in the United States!
Therefore, the Sacramento Dentistry Group encourages you not to fear fluoride in your water. Indeed, it’s the lack of fluoride that represents the greater problem! A demonstrated cavity fighter, enamel strengthener, and fracture reducer, we encourage you to come to us if you have any questions about the benefits of fluoride for dental health.