Water fluoridation: When current research contradicts public practices.

January 25, 2020, marked the 75th anniversary of intentional water fluoridation in the United States (US). Once touted as a significant advancement in public health, current research now raises interesting questions about water fluoridation in light of other effective fluoride treatment methods and the potential for adverse health impacts. Globally, 350 million people (only 5% of the world’s population), including over 200 million Americans, consume artificially fluoridated water. In Europe, 98% of the population drink unfluoridated water. Several countries, including France, Germany, the Netherlands, Denmark, and Sweden, have banned fluoridation in the early 1990s and reinforced oral health behavior and applicability of preventative measures, such as fluoride toothpaste. Some European countries have optional salt fluoridation, but the majority have neither fluoridated water nor fluoridated salt (Aoun, Darwiche, Al Hayek, & Doumit, 2018). Comparing countries with and without fluoridated water show little variation in the rate of reduction or level of dental caries (Peckham, 2012). Also, studies show a decline in caries prevalence after the cessation of water fluoridation and the implementation of alternative fluoride delivery programs in some countries (Künzel & Fischer, 2000; Künzel, Fischer, Lorenz, & Brühmann, 2000).

In the US, the dominant narrative is that water fluoridation, with a recommended concentration of 0.7 mg/L for all ages (US Department of Health Human Services Federal Panel on Community Water, 2015), is safe and effective, despite the mounting evidence showing the potential harms of exposure to fluoride, including low IQ, neurobehavioral deficits, and endocrine dysfunction (National Toxicology Program [NTP], 2019). Water fluoridation is endorsed by the Centers for Disease Control and Prevention (CDC), American Dental Association (ADA), American Nurses Association (ANA), and other major public health bodies. However, their endorsement may be predicated on old science.This editorial argues the uncertain benefits of water fluoridation on dental caries prevention needs to be weighed against the potential adverse impacts on human health.

1 QUESTIONS ABOUT THE SAFETY AND EFFECTIVENESS OF WATER FLUORIDATION

1.1 Safety

There is a growing body of evidence finding neurotoxic effects of fluoride, especially in children and from fetal exposures (Grandjean, 2019; Green et al., 2019; National Academies Press [NAP], 2020; Riddell, Malin, Flora, McCague, & Till, 2019; Till, Green, Flora, et al., 2020; Till, Green, & Lanphear, 2020). In 2006, the National Academies reviewed the scientific literature on the health effects of fluoride exposure and determined that chronic fluoride exposure could cause enamel fluorosis and increase the risk of bone fracture. At that time, it concluded that “studies of the potential neurotoxicity of fluoride exposure lacked sufficient detail and did not allow definitive conclusions” (The National Academies Press [NAP], 2006). Despite this uncertainty, U.S. public health agencies encouraged and continued funding water fluoridation.

In September 2019, the NTP, a division of the U.S. Department of Health and Human Services that provides evaluations of substances for potentially harmful human health effects, released a draft evaluation of neurodevelopmental and cognitive impacts related to fluoride exposure. The NTP report concluded that “fluoride is presumed to be a cognitive neurodevelopmental hazard to humans. This conclusion is based on a consistent pattern of findings in human studies, across several different populations, showing that higher fluoride exposure is associated with decreased IQ or other cognitive impairments in children.” In March 2020, the NAP published a review of the draft NTP monograph and stated: “Given the issues raised by the committee regarding the analysis of various aspects of some studies and the analysis, summary, and presentation of the data in the monograph, the committee does not find that NTP has adequately supported its conclusion.” But it also emphasized, “That finding does not mean that the conclusion is incorrect; rather, further analysis or reanalysis, as noted in the present report, is needed to support conclusions in the monograph.” Does this indicate that science had not made any progress since 2006 when the NAP first discussed the uncertainty about potential neurotoxicity effects of fluoride exposure? Or are we just ignoring the precautionary principle on the scientific uncertainty and overlooking the evidence to avoid unpleasant facts? What if fluoride in drinking water is harming our children?

1.2 Effectiveness

There are controversies in the literature regarding the independent impact of water fluoridation on the incidence of dental caries. Many studies supporting or opposing this intervention are outdated or suffer the lack of adequate control for significant confounding variables, such as oral health behaviors and other sources of fluoride consumption in their studies. The World Health Organization (WHO, 2004), a promotor of water fluoridation in developing countries, states that the decision to implement a water fluoridation program should rely upon an understanding of the population’s oral health behavior, diet, the volume of water consumed, dental caries risk, the level of public dental awareness, and the general availability of alternative vehicles (e.g., fluoridated toothpaste). In the US, this public health intervention continues without considering the above indicators and knowing that fluoride mostly helps tooth decay by topical means, mainly using fluoride toothpaste, which is adequately available in the US (Anonyomous, 2000; Kanduti, Sterbenk, & Artnik, 2016; Warren & Levy, 2003).

The optimal intake of fluoride in children, which has been widely accepted for decades (0.05–0.07 mg fluoride per kilogram of body weight), is primarily based on data initially obtained in the 1930s and 1940s (Mcclure, 1943). At the time, there was a limited understanding of how fluoride works to prevent dental caries, and there were no or minimal topical dental fluoride products available (Warren et al., 2009). This level of intake can be challenging to regulate individually due to different water intake patterns and other sources of fluoride consumption, such as formula, toothpaste, and tea (CDC, 2015; Till, Green, Flora, et al., 2020; Till, Green, & Lanphear, 2020; Waugh, Godfrey, Limeback, & Potter, 2017). How do we know when children have reached the optimal level of fluoride intake and when and how should they stop taking more fluoride? Just as we in nursing evaluate the risks and benefits of a particular treatment, fluoridating water needs to be evaluated similarly. Even if water fluoridation has the potential to prevent dental caries, if recent evidence is, in fact, accurate, it could never justify potential permanent brain damage in children.

1.3 Ethical controversies

The crucial ethical issue surrounding water fluoridation is the addition of medicine to public water supplies without individuals’ consent. Unlike any other medical decisions that we take, many US citizens have no choice in the selection of fluoridated or nonfluoridated water. The balancing of individual rights versus societal health is similar to other issues in public health, such as adding Vitamin D to milk, iodine to salt products or thiamine to flour. On the other hand, in many environmental conditions, health care providers can educate clients to eliminate exposures through affordable methods; however, the elimination of fluoride exposure through drinking water is difficult and not just because not everyone can afford it. Fluoride consumption through drinking water that is the primary source of fluoride exposure (Grandjean, 2019), can be reduced by drinking spring water or through three relatively costly filtering processes of reverse osmosis, deionizers (which use ion?exchange resins), and activated alumina of filtrations (Shen & Schäfer, 2014; Tang, Kovalsky, He, & Waite, 2015).

Furthermore, water fluoridation provides the same dose of fluoride for all ages. This “one size fits all” approach not only does not make sense scientifically but also brings other critical ethical and dose?response concerns. It leaves us to question one dose of fluoride’s safe applicability for young and old, thin and overweight, and black and white.

2 CONCLUSION

What do the findings of new studies mean for the children and growing fetuses being exposed to a potentially neurotoxic chemical? How can we so easily ignore the serious red flags of the evidence supporting the potential neurotoxicity of water fluoridation over possible dental caries reduction? The questions that exist in the contemporary evidence form a cloud over the 75th anniversary of water fluoridation.

It is clearthat tooth decay is a serious health issue and we should be fully supportive of effective and safe efforts to address it, including the promotion of better nutrition, use of fluoride toothpaste, better home dental habits, and increased access to professional dental care, especially for low?income populations. The public water fluoridation intervention needs to be reevaluated in light of new evidence on potential neurotoxicity, oral health behavior, practice changes since the 1960s, and ethical considerations. It has become impossible to ignore the warnings that recent scientific studies have raised. Science does not stand still, and neither should nurses. Based on the current evidence that shows potential health risks, is it not time for ANA, CDC, and other major public health bodies to update their websites according to new evidence and change their position considering a more precautionary approach?

In the face of the continuous controversy over the benefit of intentional water fluoridation, although nurses should keep themselves up to date and rely on the precautionary approach to educate their clients to use fluoridated toothpaste and eliminate fluoridated water, whenever possible, nurse advocacy seems to be the most fundamental approach to reshaping this public health intervention. Currently, the Alliance of Nurses for Healthy Environments (ANHE) is discussing this issue with the CDC, ANA, and the American Public Health Association. The latest evidence must be brought to the attention of the endorsers so they can reconsider their positions. Nurse scientists are asked to add to the current evidence about water fluoridation benefits and harm through their research. Furthermore, nurses should speak up and challenge their legislators about the benefits of water fluoridation and ask them to expand choice rather than restrict choice.

*Original article online at https://onlinelibrary.wiley.com/doi/full/10.1111/phn.12758