An Assessment of Community Water Fluoridation

Water treatment is a vital public service that ensures that our water supply is safe to drink. However, issues regarding water treatment generally attract public attention only when the safety of water for consumption or recreation is called into question. A questioning of water safety often prompts a response, governmental or humanitarian; however such responses sometimes not only fail to solve problems, they exacerbate those problems. In the 1970s, humanitarian groups in Bangladesh installed deep tube wells to prevent waterborne illnesses caused by drinking surface water. These wells significantly decreased deaths due to waterborne pathogens, but after residents reported concerning symptoms, the ground water was tested and it was found that it contained arsenic at concentrations well over safe limits. As a result, about 35- 77 million people were exposed to dangerously high levels of arsenic, which may have lasting effects on the cardiovascular system and contribute to the development of cancer (Argos et al. 252).

Major water treatment crises are not isolated to developing countries. In 2015, it was found that water supply in Flint, Michigan was not being treated with corrosion controls, causing lead and iron from the pipes to leech into the water supply. This treatment would have only cost about $100 a day and would have prevented the residents of Flint from being exposed to toxic amounts of lead, which can lead to irreversible neurological damage in both children and adults and can even impact the health of future generations (Ganim). In both of these cases, no preventative actions were taken and it required the poisoning of large groups of people in order to attract the attention of the media and policymakers. In order to prevent crises like these from occurring, it is important to assess and scrutinize the safety and environmental effects of all forms of water treatment, including those forms usually considered innocuous. One of these innocuous forms of water treatment that deserves a closer examination is community water fluoridation. Despite its prevalence in the US and many countries around the world, most Americans are uninformed about the risks and benefits of water fluoridation.

Community Water Fluoridation (CWF) is the practice of introducing fluorine-containing molecules into municipal water supplies in order to decrease the prevalence of tooth decay. Fluorosilicic acid is the additive most commonly used in CWF, although sodium fluorosilicate or sodium fluoride are sometimes used depending on the budget and population of the community (“Water Fluoridation Additive Fact Sheet”). CWF began in 1946 when Grand Rapids, Minnesota, became the first city to fluoridate their water supply (Pizzo et al. 190). Since then, CWF has been introduced widely throughout the United States and other countries, with 74.6% of the US population receiving fluoridated water in 2012 (“2012 Water Fluoridation Statistics”).

Because of the wide range of results in published in literature, the public receives mixed messages about the safety of CWF through the media and other organizations. While the Centers for Disease Control and Prevention (CDC) considers CWF to be one of the most important public health achievements in the twentieth century, interest groups, namely the Fluoride Action Network (FAN), lobby against water fluoridation (“10 Greatest Public Health Achievements in the 20th Century”). Both of these organizations are biased in what they believe is best for public health, and thus purposely select studies that supports their claims, even though their choices are not representative of all available research. As a result, Americans are presented with a confusing and misleading picture of the risks and benefits of CWF.
 
Although it has been seventy years since CWF was first implemented and it is widely endorsed by national and international health organizations, current research does not conclusively support that it is effective in decreasing the incidence of tooth decay or that it is a significant risk factor for chronic illnesses (Cheng, Chalmers, and Sheldon 699). These ambiguous results are primarily indicative of the difficulty of measuring impact of exposure to low concentrations of fluoride over a lifetime (Cheng, Chalmers, and Sheldon 700). It is also difficult to differentiate the effects of CWF from those of other environmental factors that may also affect dental health or contribute to the development of chronic illnesses. Due to this uncertainty, CWF may not be the most efficient use of governmental resources. Additionally, studies have shown that fluoride is toxic to many economically important freshwater species (Camargo 251; Gonzalo and Camargo 244). Because of the risks that CWF poses to the environment, as well as the lack of a strong correlation between CWF and positive effects on human health, other efforts to protect public dental health, such as distributing dental health information in schools and improving Medicaid coverage, should be considered as potential alternatives to CWF. Further research should be conducted to ascertain the potential risks of and benefits of CWF and other public dental health initiatives.
Though the effectiveness of fluoride itself is well-established, there is a lack of conclusive evidence for both the safety and effectiveness of CWF. CWF-specific studies are necessary because CWF relies on lower concentrations of fluoride applied to the teeth for shorter periods of time, unlike other fluoride treatments. Although the effects of CWF can be assessed through epidemiological studies of fluoridated areas, researchers have had little success in this venture. In a meta-analysis of around 3200 peer-reviewed research papers concerning the fluoridation of water supplies, K.K Cheng, Iain Chalmers, and Trevor Sheldon found that the
 
research on this subject is of overall poor quality. They noticed that several of the research papers contradicted each other, and the conclusions of many other papers were based on data with high statistical uncertainty and small sample sizes (Cheng, Chalmers, and Sheldon 699). They attribute these results to conformation bias on the part of the researchers, who may be consciously or unconsciously manipulating statistical models to get the results that they believe to be true (Cheng, Chalmers, and Sheldon 700). Further statistical analysis of research is needed to determine the extent of the bias and to more accurately assess the relationship between CWF and tooth decay.

Similarly, there is little evidence to support the assertion that CWF is a cause of chronic illness. Though some studies that suggest CWF may contribute to chronic illnesses, the majority of these studies were conducted on individuals exposed to abnormally high levels of fluoride due to poor control of fluoride pollution (Meenakshi and Maheshwari 457; Ding et al. 1943). Studies conducted on individuals exposed to lower concentrations of fluoride tend to show no correlation between CWF and chronic illness (Hillier et al. 267; Xiong et al. 114). As the impact of the low concentrations of fluoride used in CWF is difficult to measure with any certainty, it cannot be reasonably assumed that CWF significantly contributes to chronic illness. Further research using populations exposed to the lower concentrations of fluoride typically used in CWF is necessary to determine whether or not CWF contributes to chronic illnesses (Cheng, Chalmers, and Sheldon 702).

The only health risk that is conclusively associated with fluoride exposure is dental fluorosis. However, at low concentrations of fluoride such as those typically used in municipal water supplies, dental fluorosis is generally mild and only of cosmetic concern, requiring no treatment. Dental fluorosis is characterized by “lusterless, opaque white patches in the enamel, which may become stained yellow to dark brown,” and occurs when fluoride is ingested regularly when teeth are being formed (Kaminsky et al. 268). At higher concentrations of fluoride than used in CWF, increased brittleness and pitting of the teeth can occur, which may require medical attention. Though the extent of fluorosis typically caused by CWF is negligible, it is important to monitor the levels of fluoride in water supplies to prevent them from getting high enough to become a public health concern.

The likelihood of developing severe fluorosis as a result of CWF is extremely low, but this does not mean that CWF does not pose any other health risks. Although there are no known health threats associated with ingesting low concentrations of fluoride, epidemiological studies should be improved in order to determine the potential risks of this practice with more certainty. Because so much is unknown about the effects of fluoride on the body when it is swallowed, it may be safer to avoid CWF in favor for other methods of preventing tooth decay. CWF has been used for almost seventy years in the United States, and the possibility of negative health effects still has not been ruled out, so it may be time to look for safer and more effective methods of preventing tooth decay to replace CWF until it can be confirmed that CWF is free of any significant health risks.

The health benefits of fluoride primarily occur when there is direct contact between fluoride and the teeth, not when it is swallowed as in CWF. According to a research review published in Italy in 2007, “Several laboratory investigations have clearly demonstrated that the presence of low levels of fluoride (0.03 ppm or higher) in saliva and plaque fluid reduces the rates of enamel demineralization during the caries process and promotes the remineralization of early caries lesions”; however, “the level of fluoride incorporated into enamel by systemic ingestion was proved to have no significant effect in preventing [or] reversing caries” (Pizzo et al. 191). This finding suggests that CWF is not the most efficient method of fluoride delivery, even though it is easy to implement and inexpensive to maintain. Another research review found that “topical fluoride is more effective than supplements” and other forms of fluoride that are swallowed, including fluoridated water (Lewis 6). The use of other topical forms of fluoride, including fluoridated toothpastes, mouthwashes, and fluoride varnishes are more effective than CWF because they involve prolonged contact of fluoride with the teeth. Although these products contain concentrations of fluoride that are many times greater than fluoridated water, they are not swallowed and therefore do not contribute to fluorosis if used correctly.

CWF has been used for almost seventy years, yet it is debatable as to whether its use has resulted in a significant reduction in tooth decay during that time. In a comparison of the frequency of cavities in countries with and without CWF, researchers found that all of the countries showed a similar decrease in the frequency of cavities between 1965 and 2005, even in countries that did not fluoridate their water during that time (Cheng, Chalmers, and Sheldon 699). Because topical fluoride products are more effective than oral fluoride products such as CWF, encouraging the use of fluoridated toothpastes and other products instead of fluoridating the water supply may be more effective in preventing tooth decay than CWF.

In addition to the lack of evidence for CWF being an effective preventative measure against tooth decay, CWF may also be harmful to the environment. Even though very low concentrations of fluoride can be present in the water naturally because of fluoride-containing rocks, the concentrations of fluoride typically introduced to the water supply for CWF are enough to pose a threat to aquatic organisms (“Community Water Fluoridation”). A 2008 research review reported that concentrations of 0.5 ppm and higher adversely affect the health of marine invertebrates and fish and that “safe levels below this fluoride concentration are
 
recommended in order to protect freshwater animals” (Camargo 251). This study also found that sensitive freshwater species, notably salmon, fish larvae, and invertebrates are affected at even lower concentrations of fluoride, as Chinook and Coho salmon may be sensitive to fluoride concentrations “as low as 0.2 [ppm]” (Camargo 260). The maximum contamination level for fluoride mandated by the Environmental Protection Agency (EPA) is 4 ppm, and the level for fluoridation in municipal water supplies is 0.7 ppm as recommended by the HHS, which are both significantly greater than the safe levels for aquatic organisms suggested by the study (“Basic Information about Fluoride in Drinking Water”; “HHS Issues Final Recommendation for Community Water Fluoridation”). Because current governmental regulations do not consider the negative effects that fluoride may have on the environment, the fluoride introduced for the purpose of CWF has the potential to be present at concentrations that are potentially toxic to aquatic organisms that are important to both the ecosystem and the economy.

Introducing concentrations of fluoride greater than 0.2 ppm not only endangers the salmon population, but also the populations of predators that depend on the salmon. According to the National Wildlife Federation, Chinook salmon are a keystone species in the Pacific Northwest and are a “vital food source for a diversity of wildlife, including orca whales, bears, seals and large birds of prey” (“Chinook Salmon”). Chinook salmon are endangered and face many other threats, including overfishing and habitat loss, in addition to exposure to potentially toxic levels of fluoride (“Chinook Salmon”). Because water fluoridation requires the use of concentrations of fluoride that are higher than those that can be tolerated by sensitive aquatic organisms, discontinuing water fluoridation in communities whose water supplies drains into salmon habitat, or the habitat of another ecologically important aquatic species, would be a
 
relatively easy way to remove a threat to the population and help to maintain a healthy ecosystem in the area.
Fluoride is a biologically persistent pollutant and does not break down into a less toxic form over time. This persistence makes it possible for fluoride to become concentrated in the tissues of organisms that ingest fluoridated water or other organisms that contain fluoride in their tissues. Like all chemicals, a large enough dose of fluoride can have toxic effects. A 2011 study conducted in Spain found that fluoride bioaccumulates in the tissue of signal crayfish, “[posing] a potential risk to human health when signal crayfish from fluoride polluted areas are consumed” (Gonzalo and Camargo 244). Because there is evidence that fluoride can be stored in muscular tissues of crayfish, bioacccumulation likely occurs in other, commercially important species of aquatic invertebrates and fishes. Though it is currently unlikely that the low concentrations of fluoride found in municipal water supplies is harmful to humans, higher concentrations of fluoride are known to cause fluorosis and may also contribute to the other chronic health conditions. Even though the amount of fluoride contained in seafood living in water containing higher than normal levels of fluoride is unknown and likely varies between bodies of water, discontinuing CWF in areas where a large amount of commercial and recreational fishing occurs would decrease the risk of consuming toxic levels of fluoride in seafood.

Furthermore, many proponents of water fluoridation argue that CWF reduces socioeconomic inequalities in health care by providing people with free fluoride treatment that they may not otherwise receive. However, there is limited evidence to support that people of lower socioeconomic status experience more tooth decay than those of higher status, and the evidence that CWF helps to alleviate this disparity is even more limited (Pizzo et al. 191). CWF does little to correct the inequities that are ignored by Medicaid and may even be detrimental to
 
the advancement of public health policy, as people may assume that CWF is a suitable remedy for inequity in dental health care. Because US adults under Medicaid are currently not guaranteed any kind of dental health care, adults under Medicaid are unlikely to receive treatment for cavities and other oral health problems (“Dental Care”). Improving Medicaid coverage may have a more major impact than CWF, but it is likely to be much more costly, so further analysis is needed to determine if this could potentially be a worthwhile investment in public health.

Though making changes to Medicaid would be costly, there are other policies and practices that can be implemented or built upon that could create an impact to rival CWF. Schools have the ability to educate students and their parents about the importance of dental health and preventative dentistry. They could also provide parents who may not be able to afford dental treatment with information regarding resources in their community where they may be able to receive dental services and products such as fluoridated toothpaste and dental floss for their family at a lower cost.

Because of the lack of evidence to support the effectiveness of CWF, as well as its known negative impacts on the environment, the widespread use of CWF needs to be reevaluated. As CWF does not reliably reduce socioeconomic inequities in oral health care, other public health initiatives should be considered in order to increase access to needed treatment; and further epidemiological research needs to be conducted in order to come to more substantial conclusions regarding the safety and effectiveness of CWF.