Carstairs Responds

Both Newbrun and Friedman’s letters accuse me of opposing community water fluoridation (CWF). This was not the point of my article. My article examines the arguments being put forward by scientists in the 1930s, 1940s, and 1950s, to understand how the debate over CWF played out. Despite attempts to make science as bias-free as possible, historians and philosophers of science have shown that scientific research and debates are influenced by political, social, and cultural factors. My article maintains that evidence of the safety of water fluoridation mounted quickly and that early studies showed substantial reductions in cavities. I did not claim that water fluoridation is toxic nor was I trying to “legitimize the unsubstantiated claims of antifluoridationists” as Friedman argues.

I did outline the arguments of scientists who believed that there might be danger in consuming too much fluoride. I made the point that dentists were understandably keen to have a measure that would significantly decrease childhood caries, while also enhancing the scientific prestige of their profession. As a result, a number of activist dentists pushed for the approval of CWF before the long-term studies were completed. The quick approval of CWF by the American Dental Association, the American Medical Association and other bodies closed down the debate, making it seem that there was unanimous agreement in favor of CWF and that further research was unnecessary.

Proponents of CWF were quick to dismiss concerns about the long-term safety of consuming fluoridated water, and they accused their opponents of being paranoid cranks (à la Dr. Strangelove). This may have contributed to the situation York researchers uncovered in 2000, when they published a systemic review of the research into CWF, which expressed dismay over the quality of research in preceding decades.¹ In short, my article is about the scientific debate over CWF in the very early years of its implementation; I am not making claims about the value of CWF today.

Friedman argues that I critique the early fluoridation studies for not being blinded and claims that it would be impossible to blind a study of fluoridation. I agree. That being said, I do think that lack of blinding may have influenced the results of these early studies, which showed the benefits of fluoridation to be much greater than later studies indicated.² Admittedly, later studies of CWF are complicated by the “halo” effect: people who live in communities that lack CWF still drink beverages made in places that have CWF, making it very difficult to determine the impact of CWF. Studies of the effectiveness of CWF are further complicated by the widespread use of fluoridated toothpastes. Moreover, children in both fluoridated and unfluoridated communities get far fewer cavities than before.^3,4

Newbrun compares the introduction of water fluoridation to the initial use of penicillin. This is a faulty comparison. Tooth decay, at least in most cases, is not a life-threatening condition. Penicillin, by contrast, saved lives with a short course of treatment, whereas CWF exposed entire populations to fluorides over the life course.

Fortunately, we all agree that there is very little evidence that CWF causes any long-term health problems. I still think that it is unfortunate that the debate over CWF grew so heated and partisan so quickly. People publishing work critical of CWF have accused the profluoridation lobby of blocking publication of their research.⁵ While I am skeptical of these claims, I think that unwillingness of many profluoridationists to broker any opposition to the measure had a stultifying effect on the research by making it unpleasant for any researcher who published work that could be interpreted as hostile to CWF. There were many reasons to implement CWF, especially in the 1950s, when children got far more cavities than they do today, but the measure was not entirely without risk, and a more extended debate would have served both science and the public well.