Fluoridation of Public Water Supplies Remains Controversial

The use of fluoride in drinking water has become an increasingly debated issue, leading some communities to remove it completely from public water supplies only to vote on reintroducing it later.


By Dr. Shilpy Bhandari

Water fluoridation was first introduced in the U.S. in 1945, and more than 70% of U.S. citizens receive fluoridated water. In this procedure, fluoride is added in public water supplies to reduce the incidence of dental caries in the community. In the U.S., the recommended concentration of fluoride in water is 0.7 parts per million (0.7ppm or 0.7mg/L). Since its initiation in the U.S., the procedure has lowered the incidence of dental cavities by up to 35%. This led the U.S. Centers for Disease Control and Prevention (CDC) to name it among the ten great public health interventions of the 20th century.

Fueling Concern

However, the use of fluoridated water to prevent tooth decay has remained controversial. Due to safety and efficacy concerns, many governments have stopped adding fluoride to public drinking water. In 2021, citizens of Brevard County in Florida and Valley Public Services which covers parts of Gloverville, Warrenville, and Graniteville in South Carolina as well as Eldora, Iowa, voted to stop using fluoridated water.

In October of 2019, a Canadian research paper correlated concentrations of fluoride in the urine of pregnant women with the IQ scores of their children after 3-4 years. The IQs of the boys (but not the girls) in fluoridated communities were 1-3 points lower than those of boys in non-fluoridated communities. Another long-term study conducted in Mexico and published in 2017 had a similar conclusion. A 2012 analysis of 27 studies from China also found a correlation between high fluoride levels and lower IQ scores.

Experts point out that studies correlating fluoride water and IQ have limitations, and it’s impossible to design an ideal experimental study. The studies must also be controlled for other variables such as sugar consumption, socio-economic status, consumption of bottled water, and oral habits.

Studies on the effect of water fluoridation on dental health have found mixed results. On one hand, non-fluoridated countries (e.g., Belgium, Luxembourg, and Denmark) have better dental health than the U.S.

On the other hand, dentists in Calgary, Canada say they are seeing bigger, deeper, and more aggressive cavities since fluoridated water was phased out of the city’s tap water in 2011. An ADA summary of research supports this claim and suggests that tooth decay increases by 50% -149% three to five years after stopping the supply of fluoridated water.

In Calgary’s upcoming municipal election in October 2021, citizens will hold Calgary’s seventh plebiscite on the decision to reintroduce fluoridation of the municipal water supply.

Benefits of Fluorinated Water

  • Tooth decay prevention: Drinking fluoridated water sustains a small amount of fluoride in the saliva and dental plaque (sticky biofilm on the surface of teeth). The presence of small amounts of fluoride is desirable, as it slows down bacterial activity in the oral cavity. It integrates with the enamel on the tooth surface to make the enamel stronger and resistant against decay-causing bacteria, and re-mineralizes or reverses any early-stage dental cavities. According to a review by Cochrane Oral Health, the introduction of fluoridated water has resulted in 35% lesser decays in primary teeth and 26% in permanent teeth.
  • Improves the quality of life of a larger population: Community water fluoridation reduces the incidence of dental decay. As a result, it lowers the need for root canal treatments, anesthesia, and extraction procedures. This improves the quality of life of the larger population including the poor, uninsured, children, and elderly, who may not have access to dental care.
  • Cost-effective: The supply of community fluoridated water costs about a dollar per person for a year. This is one of the cheapest and most affordable ways to prevent dental cavities.
  • Better overall health: Research suggests that children with infections in the mouth are at higher risk of developing infections in other parts of the body (e.g., ears, sinuses, and brain). This means children with cavity-free, healthy mouths are less prone to such infections, resulting in better overall health.

Cons of Fluorinated Water

  • Adverse health effects: Consumption of water with high fluoride concentration over a long period of time leads to dental fluorosis. This condition is characterized by white streaks, dark brown stains, and rough or pitted enamel. Severe cases of fluorosis are associated with an increased risk of hip fracture, malfunction of kidneys, calcification of cartilage, and cancers. Considering the adverse effects, many question if the benefits of fluoridated water outweigh the risks involved.
  • Breach in the freedom of choice: Some believe that people should not be forced to drink medicated water through public supplies. They argue that this state-imposed act is against the citizens’ freedom of choice.
  • Toxic effects of additives: Community water fluoridation involves the addition of fluoride compounds to drinking water. Commonly used additives are silico-fluorides, which are highly toxic waste products of phosphate-based fertilizer and insecticide production. The source of silico-fluorides raises safety concerns.
  • Variation in the fluoride dosage: People drink different quantities of water. They also intake fluoride through products such as toothpaste and mouthwash, and in tea, fish, and deboned meat. Since fluoride intake varies among individuals, it is difficult to control excess fluoride intake.
  • More effective alternatives: Anti-decay benefits of fluoride are topical (effective in external use) and not systemic. So, it’s better to deliver fluoride directly to the tooth through topical supplements (e.g., toothpaste, mouthwash) instead of systemic ingestion (e.g., drinking fluoridated water).
  • Questionable cause-and-effect relationship: Dental cavities are common in fluoridated low-income countries. In these countries, inadequate oral health facilities and poor oral hygiene maintenance are considered to cause dental decay. This implies a low correlation between intake of fluoridated water and caries prevention.

In Conclusion

The decision to cease drinking water fluoridation isn’t isolated to North America, as communities across the globe are becoming more proactive in what is, or isn’t put in their water supply and petitioning local governments to take action. While the ADA maintains that fluoride in public water is safe, as dental professionals our role to educate patients on the safe use of fluoride in preventing tooth decay remains key.


AuthorDr. Shilpy Bhandari is an experienced dental surgeon, with a specialization in periodontics and implantology. She received her graduate and postgraduate education from Rajiv Gandhi University of Health Sciences in India. She is also interested in evidence-based academic writing and has published several articles in international journals

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