Effects of Fluoride Exposure

Ashley

June 17, 2024

Fluoride was a given in my childhood and many others’

In the 1990’s and early 2000’s, I remember getting the fluoride varnish or mouthwash at every dentist visit. I was told this would help prevent cavities. There was never any hesitation or discussion about it, it was just part of the normal procedure. All the mainstream brands of toothpaste I remember, especially the toothpaste marketed for children, had fluoride in them. I’m sure there were other fluoride-free toothpastes out there, but I only remember using the fluoride kind. After all, we wanted to prevent cavities. Today, the topic of fluoride is more controversial and some people don’t feel comfortable with their products containing fluoride. We’ll talk through the history of fluoride, why we use it today, and some guidance on how you can make the best decision for you and your family.

What is fluoride?

F is the symbol for fluorINE which is one of the naturally occurring elements in the periodic table. FluorIDE is a negatively charged ion. It exists in combination with positively charged ions, like sodium for example, to make sodium fluoride. Fluoride occurs in various forms naturally in water, soil, and air. It has been found anywhere from 0.01 parts per million (ppm) up to 100 ppm in freshwater. For reference, 1 ppm is equivalent to 1 inch out of 16 miles, so we’re talking very small numbers here!

While some sources of fluoride occur naturally, today fluoride is also intentionally added to products we use or consume. Some typical forms that you will see added to products are sodium fluoride (NaF), monofluorophosphate (MFP), or stannous fluoride (SnF2). In the United States, you will find fluoride added to most city water supplies. Processed foods and drinks as well as infant formula often contain fluoride because they are processed with fluoridated water. Lastly, fluoride is commonly added to toothpaste, mouthwash, teeth varnishes, and teeth gels. Water and other drinks typically consist of 75% of a person’s average intake of fluoride. 

A little bit of fluoridation history

Now that we know what fluoride is, let’s find out why fluoride is in so many products. It is a long and complex history, but I’ll try to summarize it briefly. “Dental caries”, also referred to as cavities or tooth decay, was on the rise in many industrialized developed countries. We’ll talk about why this became a problem a little later. Dental caries were affecting approximately 60-90% of children in industrialized countries. Since fluoride is naturally occurring in varying concentrations globally, some studies performed in the 1930s found a correlation between low caries prevalence in children when they were drinking water with higher amounts of naturally occurring fluoride.

This discovery eventually led to the practice of water fluoridation. Water fluoridation began in the United States in 1945, and essentially allows the intentional addition of fluoride compounds to water. Today around 70% of homes in the United States are receiving fluoridated water. Additionally, 25 other countries also practice water fluoridation to prevent caries. This fluoride discovery also led to the development of fluoridated toothpastes which began to be used widely in the mid-1970s.

Many studies were conducted since the initial discovery of fluoride preventing caries in the 1930s through 1975 (when fluoridated toothpaste became widely used). Results have clearly shown decreases in tooth decay of up to 35% in this time period. In a more recent systematic review of these studies, some concerns arose. Many of the studies were observational which is not the best study method from which to draw conclusions. There appears to be a high risk of bias in the studies as well. Given the increase in use of fluoride toothpaste and consumption of other fluoridated products, there is a question on if these study results can be extrapolated to our lives today.  

Systemic fluoride vs topical fluoride

Now that people have been using fluoridated products for many years and science has evolved, we have a better understanding of why and how fluoride works to prevent caries development. There are two ways fluoride can help – systemically and topically.

Systemic fluoride refers to ingesting fluoride (think: water, other drinks, food, supplements, and any accidental swallowing of topical tooth products). Once ingested, the fluoride is absorbed into the bloodstream. Approximately 50% of fluoride ingested gets taken up by hard tissue (bones, teeth). The remainder is excreted from the body. A small amount will also stay present in the saliva which allows it to further incorporate into our teeth. Since most people are regularly drinking water, this creates a consistent presence of fluoride available for our teeth to use. Systemic fluoride only works when teeth are developing. This means the systemic method is only applicable to children whose permanent teeth are growing.

Topical fluoride refers to fluoride application on the surface of the teeth (think: toothpaste, mouthwash, varnishes, and gels). The topical application allows the fluoride to be incorporated at the point of application on the tooth. Localized application of fluoride allows the fluoride to combine with calcium and phosphate (which is already present in your teeth and saliva) to form fluorapatite. The fluorapatite covers your teeth where demineralization has occurred and encourages remineralization to protect your tooth from further damage.

The evidence around topical use of fluoride is strong and clear that it does help repair teeth. The evidence around systemic use of fluoride is a little less clear. As you’ll find out, there is a very fine line between enough systemic fluoride to prevent decay and too much systemic fluoride which puts children at risk for developing dental fluorosis.

The root cause of caries

There is a lot of evidence showing that dental caries development is highly correlated to the sugar and simple carbohydrates in your diet. Historically, there are obvious increases in caries at the same time as sugar importation increases. The way caries develop is also well understood. Your mouth is full of bacteria and this bacteria metabolizes sugars to form acids. The acids work to demineralize your tooth enamel which contains hyrdroxyapatite (calcium and phosphate). Regardless of how “clean” you eat, there will always be a small level of sugar and starch in the diet that causes demineralization. Your teeth also have the ability to remineralize through the calcium and phosphate present in your saliva. Cavities form when the demineralization rate outpaces the remineralization rate.

Candy and chocolate plus mouth bacteria lead to acid formation. Acids lead to tooth demineralization, or calcium and phosphate migrating away from the tooth. This causes cavities.

Animal experiments were completed to provide further evidence of the impact of sugar consumption on caries development. These studies found that both the higher amount of sugar ingested and the higher frequency of ingesting sugar are contributing factors to caries development. Further studies completed in the UK and by the World Health Organization (WHO) have stated that sugars from whole fruits and sugars in milk do not contribute to caries development. It is primarily other types of sugars that should be avoided.

When I look at all this research, the craziest part to me is that instead of pointing our fingers at the root cause of caries (overconsumption of sugar and carbohydrates), it’s decided on our behalf that we need a new compound in our water and toothpaste, just so we can eat the same level of sugar and carbs while hopefully being able to prevent further tooth decay. Overconsumption of sugar and carbs can cause other health issues in addition to tooth decay. It seems that we’re always trying to put a bandaid on the situation by introducing new solutions that will “fix” the damage we’ve caused or prevent further damage rather than removing the actual root cause.

Potential effects of fluoride consumption

The benefits of topical fluoride application are clear in that it helps reduce tooth decay. The most common and most medically accepted adverse effect of fluoride addition(s) to the products we consume is fluorosis. Fluorosis occurs when more fluoride is ingested than what is needed for tooth enamel protection. This elevated level of fluoride causes fluorosis only when permanent teeth are developing. This occurs within the first three to eight years of a child’s life. Mild fluorosis is typically characterized by white streaks, lines, or specks on the teeth along with some mild surface roughness. A case of mild fluorosis cannot typically be seen with an untrained eye. More severe fluorosis is characterized as “mottled” teeth. In this case, very noticeable white opaque areas, or brown staining are visible on the teeth. Severe fluorosis also causes the teeth to be more brittle and more susceptible to decay. There are other potential concerns that are either less common or less accepted due to the evidence available:

  • Skeletal fluorosis: bones are dense, but brittle, with increased likelihood for fractures and reduced joint mobility. This is very rare, but is typically caused by high concentrations of fluoride or fluoride supplementation.
  • Acute toxicity: causes gastrointestinal issues like vomiting and diarrhea and in severe cases could cause death. This is also very rare, but is caused when someone ingests a significant amount of fluoride in a short time. This can be as low as 1 gram of sodium fluoride for a child!
  • Cancer incidence: ingesting fluoride may be tied to an increased risk in cancer or death from cancer. There are many conflicting results in these studies and this is not a medically accepted risk.
  • Lower intelligence in children (neurotoxin): human and animal studies suggest that increased consumption of fluoride decreases intelligence. These studies had many limitations and were not performed most accurately. They had potential confounding factors that were not addressed, especially for fluoride levels at the quantity humans are currently estimated to be consuming. It does seem clear that at levels far above what is standard for human consumption, there are significant intelligence and brain effects.
  • Hypothyroidism: ingestion of excess fluoride has been tied to an increased risk for hypothyroidism, but this was observed at higher levels than typically consumed.

The “optimal” level of fluoride

There are limits on fluoride for our safety, but there are some nuances to be aware of. Previously the recommendations for water fluoridation were between 0.7 – 1.2 ppm fluoride. It was assumed that children in warmer states drank more water, while children in colder states drank less water, hence the range in recommendations. Recently the Center for Disease Control and Prevention (CDC) and the American Dental Association (ADA) revised their recommendation to be 0.7 ppm across the board. This was due to concerns about a rise in fluorosis occurrence in children. Fluoride is now more available in other sources like drinks, toothpaste, and processed foods. This means children are getting more fluoride from other sources than when the limit was originally set in the 1950s.

While the CDC and ADA consider their recommendations to be “optimal fluoridation levels”, there are so many differences from one person to the next. In my opinion, the government cannot determine what is an “optimal fluoridation level” for all people. Day laborers that are spending all day outside in the sun or athletes working out multiple hours each day drink significantly more water than the average office worker. This doesn’t count other fluoride exposure from food and drinks. While ingesting (systemic) fluoride is most protective for children under 8 years old, young children also may not be able to prevent themselves from swallowing toothpaste during brushing. If this is the case, your children are not only ingesting the “optimal” fluoride levels in the water they drink. They’re also ingesting potentially much higher concentrations. It’s important for all of us to understand how much fluoride we are consuming so we can determine if that’s outside our comfort level and if we need to minimize consumption in certain areas.

How to decide if and how much fluoride is the best option for your family

Now we’ve learned a lot about fluoride and tooth decay, but I want to leave you with some items to consider to determine what’s best for you and your family.

  1. Figure out how much fluoride you’re consuming (ingesting) in your daily life. Review the information in this post, along with other resources if needed, and figure out if that’s something you’re comfortable with. If you are comfortable with it, great! You don’t need to change anything and you’ve learned all about why fluoride can be helpful in preventing tooth decay. If you’re not comfortable with it, you can explore some other options to decrease your exposure, so keep reading!
  2. To prevent tooth decay without the use of fluoride, first look at adjusting your eating habits. This is how you disrupt the root cause of tooth decay. Avoid eating foods or drinking beverages with significant amounts of sugar often. According to “Ask the Dentist”, families that primarily eat meat, fruits, and vegetables and primarily drink water rarely have cavities. When you do eat or drink something high in carbs or sugar, he recommends rinsing out your mouth directly afterwards and brushing your teeth 30-45 minutes afterwards to minimize negative impacts on your teeth.
  3. Good dental hygiene is an important step to preventing tooth decay without the use of fluoride. While consuming carbs and sugar exacerbates and quickens the pace of decay, build-up of plaque and bacteria in the mouth also significantly contribute. It’s important to disrupt plaque buildup through brushing and flossing to prevent decay.
  4. Consider switching your toothpaste to a hydroxyapatite toothpaste rather than a fluoride toothpaste. Hydroxyapatite is relatively new as it was first commercially available in Japan in 1993. It is a synthetic version of the compound that already makes up our teeth – calcium and phosphate. While there are not as many studies evaluating hydroxyapatite as there are for fluoride, the initial studies are promising. One study compared a neutral toothpaste (no fluoride or hydroxyapatite) to a toothpaste containing 500 ppm fluoride, a toothpaste containing 1400 ppm fluoride, and a toothpaste containing hydroxyapatite. From this study, both the 1400 ppm fluoride and the hydroxyapatite toothpastes showed significant improvements compared to the neutral and 500 ppm fluoride toothpastes. Images of the teeth from this study also indicate a significant reduction in surface roughness when the hydroxyapatite toothpaste was used compared to the 1400 ppm fluoride toothpaste. As mentioned before, your teeth typically undergo demineralization and remineralization processes; decay happens when demineralization outpaces remineralization. By using a hydroxyapatite toothpaste you are effectively increasing the amount of calcium and phosphate available in your saliva to take part in the remineralization efforts of your teeth. Hydroxyapatite appears to penetrate deeper into the tooth to help with remineralization, whereas fluoride appears to primarily offer surface protection from decay. Some studies have also found that hydroxyapatite toothpaste helps decrease tooth sensitivity and helps to whiten teeth. Naturally occurring hydroxyapatite is around 20 to 40 nanometers (nm). By using nano-hydroxyapatite, you’re most closely mimicking what is already in your teeth and potentially increasing the capability of remineralization. While nano-hydroxyapatite appears to be best for remineralization capability, the European Scientific Committee on Consumer Safety (SCCS) has not deemed nano-hydroxyapatite safe yet. There is inconclusive data on the genotoxic potential of nano-hydroxyapatite (i.e. damage to DNA). Nano-particles are relatively new and have the potential to cross the blood-brain barrier, which is the cause for concern. The good news is that the majority of other toxicological tests that have been performed on nano-hydroxyapatite have passed. 

Recommendations for controlling fluoride exposure

If you want to remove fluoride altogether, consider all of the areas mentioned above where you find fluoride nowadays! The largest contributor is water and other beverages. Consider installing a water filter that removes fluoride from your tap water. Look into the other beverages you consume to see if they are produced with fluoridated water or if fluoride is added to them. You’ll also want to consider switching your dental hygiene products. This includes mouthwash and toothpaste as well as products used at your dentist’s office. Your dentist should be willing and able to accommodate this request. They can skip the fluoride varnish or mouthwash that they would typically give to children if you request it.

If you still want to use fluoride to prevent decay, it seems that using a topical method at high concentration (> 1000 ppm) is most likely to provide the desired effect. This method has the most significant data backing it up to prevent tooth decay. Your dentist can also write you a prescription for a higher dose of fluoride (~5000 ppm) if you have significant demineralization concerns or issues. The only caution I would mention is to be extra careful if your child is using something like this. They may not understand or be able to control their swallowing well enough during tooth brushing or other dental hygiene practice to prevent ingestion of this high concentration, which could have adverse effects.

    My take on fluoridation and how I control ingestion

    Product and water fluoridation is an interesting topic. It is surprisingly light on research, particularly in the past few decades after product and water fluoridation became relatively mainstream in industrialized countries. I would argue that the research is far from complete and worth the continued investment.

    While I would encourage you to come to your own decision based on your comfort level with the above information, I can share with you some guidelines for what my husband and I practice. This is by no means a recommendation for you, just a personal reference. We currently do not have a water filter that will remove all fluoride from our water supply. We do limit our fluoride exposure by limiting processed food and beverage intake. Additionally, we use a nano-hydroxyapatite toothpaste from BITE rather than fluoride toothpaste. I admit limiting processed food and beverages was primarily done for health purposes, and our hydroxyapatite toothpaste change was mainly done for environmental purposes, with the side benefit of avoiding fluoride!

    Ashley holding a jar of toothpaste tablets from BITE, her favorite fluoride-free and zero waste toothpaste.

    While I am always a fan of reducing risk of exposure to potential harmful materials, we can never live a completely toxin-free lifestyle. We have to pick our battles! If we have children one day, that’s where I see more of a concern. Their bodies are smaller, so it requires a much smaller concentration to see potentially harmful effects. Let me know if you plan to make changes to your fluoride intake in the comments below!

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    Ashley

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