Opposition to the addition of fluoride to drinking water arises from political, ethical, economic, and health considerations. International and national agencies and dental associations across the world support the safety and effectiveness of water fluoridation. Proponents see it as a question of public health policy and equate the issue to vaccination and food fortification, citing significant benefits to dental health and minimal risks. In contrast, opponents view it as an infringement of individual rights, if not an outright violation of medical ethics, on the basis that individuals have no choice in the water that they drink, unless they drink more expensive bottled water. A small minority of scientists have challenged the medical consensus, variously claiming that water fluoridation has no or little cariostatic benefits, may cause serious health problems, is not effective enough to justify the costs, or is pharmacologically obsolete.
Opposition to fluoridation has existed since its initiation in the 1940s. During the 1950s and 1960s, conspiracy theorists claimed that fluoridation was a communist plot to undermine American public health. In recent years, water fluoridation has become a prevalent health and political issue in many countries, resulting in some countries and communities discontinuing its use while it has expanded in others. The controversy is propelled by a significant public opposition supported by a minority of professionals, which include researchers, dental and medical professionals, alternative medical practitioners, health food enthusiasts, a few religious groups (mostly Christian Scientists in the U.S.), and occasionally consumer groups and environmentalists. Organized political opposition has come from libertarians, the John Birch Society,, Robert F. Kennedy Jr., and the Green Party of the United States.
Proponents of fluoridation have been criticized for overstating the benefits, while opponents have been criticized for understating them and for overstating the risks. Systematic reviews have cited the lack of high quality research for the benefits and risks of water fluoridation and questions that are still unsettled. Researchers who oppose the practice state this as well. According to a 2013 Congressional Research Service report on fluoride in drinking water, these gaps in the fluoridation scientific literature fuel the controversy.
Public water fluoridation was first practiced in 1945 in the U.S. As of 2015, about 25 countries have supplemental water fluoridation to varying degrees, and 11 of them have more than 50% of their population drinking fluoridated water. A further 28 countries have water that is naturally fluoridated, though in many of them there are areas where fluoride is above the optimum level. As of 2012, about 435 million people worldwide received water fluoridated at the recommended level, of whom 57 million (13%) received naturally fluoridated water and 377 million (87%) received artificially fluoridated water. In 2014, three-quarters of the US population on the public water supply received fluoridated water, which represented two-thirds of the total US population.
Medical consensus National and international health agencies and dental associations throughout the world have endorsed water fluoridation as safe and effective. The views on the most effective method for community prevention of tooth decay are mixed. The Australian government states that water fluoridation is the most effective means of achieving fluoride exposure that is community-wide. The World Health Organization states water fluoridation, when feasible and culturally acceptable, has substantial advantages, especially for subgroups at high risk, while the European Commission finds no advantage to water fluoridation compared with topical use.
FDI World Dental Federation supports water fluoridation as safe and effective. the European Academy of Paediatric Dentistry, and the national dental associations of Australia, Canada, and the U.S. The American Dental Association calls water fluoridation "one of the safest and most beneficial, cost-effective public health measures for preventing, controlling, and in some cases reversing, tooth decay."
In the English speaking nations—the United States, Canada, UK, Australia and New Zealand, all of which practice water fluoridation—many medical associations and authorities have published position statements and endorsed water fluoridation. The U.S. Surgeon General, the American Public Health Association, the Royal Commission on the National Health Service, Australian Medical Association, New Zealand Medical Association, and Health Canada support fluoridation, citing a number of international scientific reviews that indicate "there is no link between any adverse health effects and exposure to fluoride in drinking water at levels that are below the maximum acceptable concentration of 1.5 mg/L." The Centers for Disease Control and Prevention listed water fluoridation as one of the ten great public health achievements of the 20th century in the U.S., Contains H. Trendley Dean, D.D.S. Reprinted in: along with vaccination, family planning, recognition of the dangers of smoking, and other achievements.
In Israel, the Israeli Association of Public Health Physicians, the Israel Pediatric Association, and the Israel Dental Association, support fluoridation. The World Health Organization, looking at global public health, identifies fluoride as one of a few chemicals for which the contribution from drinking-water to overall intake is an important factor in preventing disease. This is because there is clear evidence that optimal concentrations of fluoride provide protection against cavities, both in children and in adults.
There is a minor scientific view against water fluoridation. The scientists or doctors who oppose water fluoridation argue that it has no or little cariostatic benefits, may cause serious health problems, is not effective enough to justify the costs, and is pharmacologically obsolete.
Evidence Proponents and opponents have been both criticized for overstating the benefits or risks, and understating the other, respectively. Systematic reviews have cited the lack of high-quality research for the benefits and risks of water fluoridation and questions that are still unsettled. A 2007 Nuffield Council on Bioethics report concluded that good evidence for or against water fluoridation is lacking. Researchers who oppose the practice state this as well. According to a 2013 Congressional Research Service report on fluoride in drinking water, these gaps in the fluoridation scientific literature fuel the controversy. John Doull, chairman of the 2006 National Research Council committee report on fluoride in drinking water, has stated a similar conclusion regarding the source of the controversy: "In the scientific community, people tend to think this is settled. I mean, when the U.S. surgeon general comes out and says this is one of the 10 greatest achievements of the 20th century, that's a hard hurdle to get over. But when we looked at the studies that have been done, we found that many of these questions are unsettled and we have much less information than we should, considering how long this [fluoridation] has been going on. I think that's why fluoridation is still being challenged so many years after it began. In the face of ignorance, controversy is rampant."
Safety
Fluoride can be present naturally in water at concentrations well above recommended levels, which can have several long-term adverse effects, including severe dental fluorosis, skeletal fluorosis, and weakened bones. In 1984 the World Health Organization recommended a guideline maximum fluoride value of 1.5 mg/L as a level at which fluorosis should be minimal, reaffirming it in 2006.
Fluoridation has little effect on risk of bone fracture (broken bones); it may result in slightly lower fracture risk than either excessively high levels of fluoridation or no fluoridation. Summary: There is no clear association between fluoridation and cancer or deaths due to cancer, both for cancer in general and specifically for bone cancer and osteosarcoma. Report website: Authors' summary: Authors' commentary:
In rare cases improper implementation of water fluoridation can result in overfluoridation that causes outbreaks of acute fluoride poisoning, with symptoms that include nausea, vomiting, and diarrhea. Three such outbreaks were reported in the U.S. between 1991 and 1998, caused by fluoride concentrations as high as 220 mg/L; in the 1992 Alaska outbreak, 262 people became ill and one person died. In 2010, approximately 60 gallons of fluoride were released into the water supply in Asheboro, North Carolina, in 90 minutes—an amount that was intended to be released in a 24-hour period.
Like other common water additives such as chlorine, hydrofluosilicic acid and sodium silicofluoride decrease pH and cause a small increase of corrosivity, but this problem is easily addressed by increasing the pH. Although it has been hypothesized that hydrofluosilicic acid and sodium silicofluoride might increase human lead uptake from water, a 2006 statistical analysis did not support concerns that these chemicals cause higher blood lead concentrations in children. Trace levels of arsenic and lead may be present in fluoride compounds added to water; however, concentrations are below measurement limits.
The effect of water fluoridation on the natural environment has been investigated, and no adverse effects have been established. Issues studied have included fluoride concentrations in groundwater and downstream rivers; lawns, gardens, and plants; consumption of plants grown in fluoridated water; air emissions; and equipment noise.
Efficacy
Reviews have shown that water fluoridation reduces cavities in children. A conclusion for the efficacy in adults is less clear with some reviews finding benefit and others not. Studies in the U.S. in the 1950s and 1960s showed that water fluoridation reduced childhood cavities by fifty to sixty percent, while studies in 1989 and 1990 showed lower reductions (40% and 18% respectively), likely due to increasing use of fluoride from other sources, notably toothpaste, and the "halo effect" of food and drink that is made in fluoridated areas and consumed in unfluoridated ones.
A 2000 UK systematic review (York) found that water fluoridation was associated with a decreased proportion of children with cavities of 15% and with a decrease in decayed, missing, and filled primary teeth (average decreases was 2.25 teeth). The review found that the evidence was of moderate quality: few studies attempted to reduce observer bias, control for confounding factors, report variance measures, or use appropriate analysis. Although no major differences between natural and artificial fluoridation were apparent, the evidence was inadequate for a conclusion about any differences. A 2002 systematic review found strong evidence that water fluoridation is effective at reducing overall tooth decay in communities. A 2015 Cochrane review also found benefit in children.
Fluoride may also prevent cavities in adults of all ages. A 2007 meta-analysis by CDC researchers found that water fluoridation prevented an estimated 27% of cavities in adults, about the same fraction as prevented by exposure to any delivery method of fluoride (29% average). Summary: A 2011 European Commission review concluded that water fluoridation has no known advantage over topical prevention (e.g. through fluoride toothpaste). It also found that water fluoridation has limited benefit for adults, because the continued administration of systemic fluoride after the permanent teeth have erupted has questionable efficacy in preventing tooth decay. A 2015 Cochrane review found no conclusive research in adults.