Fluoride: how a simple charged atom became such a charged topic

If you’ve ever been bored while brushing your teeth, you might have picked up your tube of toothpaste and read it over. Chances are, amongst promises of fresher breath and whiter teeth, you’ll come across the following words: “with fluoride”.

Fluoride is the ionized form of the element fluorine, meaning it consists of a fluoride atom with a negative charge. It is naturally distributed throughout the environment and can be found just about everywhere. In humans and other animals, it plays an important role in the strengthening of bones and teeth, which is why it is found in most toothpastes. It encourages the hardening of enamel and the prevention of cavities- two very important things if someone wants to avoid frequent trips to the dentist.

Is it time to brush up on your dental hygiene practices?

In many parts of the world, fluoride is also added to drinking water in small amounts in a process known as water fluoridation. This is a more controversial practice than using fluoride-based toothpastes as it does not come without medical, ethical, and environmental concerns. Yes, fluoride is known to help reduce cavities and tooth decay, and water fluoridation is the cheapest way to deliver fluoride to a large population, but its dosage cannot be easily controlled, it is a form of medical intervention without consent, and it has been linked to consequences to the environment and human health.

Water fluoridation first began in Grand Rapids, Michigan, in 1945. In the years that have followed, it has been put into practice across the world and subsequently removed in many areas as the debate has become more contentious. This is especially evident in Canada, where in British Columbia, Yukon, Quebec, New Brunswick, and Newfoundland and Labrador less than 3% of the population consumes fluoridated water. The remaining provinces vary between 20% and upwards of 60%. In contrast, in the United States around 80% of the population consumes fluoridated water- a number that the nation’s health protection agency aims to increase in the coming years. But the science is clear: in communities that do not have water fluoridation, dental health is poorer amongst children.

The key here is that children’s toothpaste does not contain fluoride. Toothpaste for adults contains fluoride in much higher concentrations than is found in fluoridated water, with toothpaste containing 1,000 to 1,100 mg/L and the World Health Organization promoting a standard rate of fluoride in drinking water of 1.5 mg/L. While the concentration in drinking water is safe and effective to prevent cavities in small children, if toothpaste is ingested it could cause a child to fall ill. For adults, good dental health is likely not due to fluoridated water, but rather good dental hygiene. In children, there is evident value to adding fluoride to drinking water.

So, what of the environmental concerns? Due to over 75 years of worldwide widespread water fluoridation (try saying that five times fast), fluoride concentration in groundwater now reaches over 30 mg/L in many areas. Greater levels of fluoride in groundwater is linked to countries where water fluoridation is more prevalent, such as the United States, India, China, Pakistan, and Thailand. These high concentrations in groundwater signify that other water systems and vegetation end up containing higher levels of fluoride than they naturally would. For plants (including human and animal feedstocks), this may not affect their growth, but the stress of excess fluoride can lead to alterations in the levels of macro and micronutrients they contain. For animals and humans, the effects are more profound. All of this fluoride in the environment does not mean superhuman teeth that can chew through glass. In fact, once fluoride levels surpass the critical 1.5 mg/L as recommended by the WHO, fluoride has the complete opposite effect on teeth and bones, leading to a condition known as fluorosis– which is exactly why fluoride is not found in children’s toothpastes.

It is never too early to start taking care of your teeth!

While 1 to 1.5 mg/L of fluoride strengthens the enamel of teeth, 1.5 to 4 mg/L results in dental fluorosis, and prolonged exposure to even higher concentrations (4-10 mg/L) results in skeletal fluorosis in both adults and children. Mild cases of fluorosis result in discolored or pitted teeth, and more severe cases report abdominal pain, nausea, vomiting, diarrhea, and even weakened bones. An estimated 200 million people worldwide suffer from fluorosis in some form, although the majority of cases are not classed as severe. Evidently fluoride is essential, but only in very specific quantities.

It’s easy to see how this issue has become of such interest amongst dental health experts and politicians. On one hand, it is evident that water fluoridation helps ensure that children are protected from cavities in an inexpensive and simple manner. On the other hand, water fluoridation systems have led to environmental contamination, meaning that many adults and children end up consuming fluoride well over the recommended limits and suffer from fluorosis. The effects of excess fluoride in the environment also extend to plants and animals. Like many subjects that cover the intersection between public health, the environment, and social issues, the choice is not clear. So the debate ensues: to fluoridate or not to fluoridate- that is the question. Ay, the threat of cavities and tooth decay will never give us pause.

Advice to consumers:

  • For adults, make sure you are regularly and thoroughly brushing your teeth with fluoridated toothpaste
  • If you are a parent to small children, inform yourself if your area practices water fluoridation. If your drinking water is not fluoridated, talk to your dental health professional about potentially using fluoridated toothpaste on your child and how to prevent fluorosis by toothpaste ingestion

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