If you already know the answer you want to hear, you will have no difficulty finding enough articles, studies, and position papers to support it. For every “yes, fluoride is safe” there’s a “no, fluoride is toxic”, and everything in between. Each side has compelling rebuttals against the other, and they all have dozens of studies to back up their claims. It’s no wonder this is a confusing and contentious issue!
Just about every conventional medical, health, and dental association, as well as both US and Canada government agencies support the use of community fluoridated water programs to help reduce tooth decay across the population. And the number of dentists that recommend toothpaste with fluoride far outweighs the number that don’t.
So why, then, is there controversy?
At the heart of the disagreements is the good ol’ precautionary principle. But how should we apply it? Settle in, and let’s get to the facts to help you make more confident decisions when it comes to fluoride in your drinking water, toothpaste, and other dental treatments.
What is Fluoride and How Does it Work?
Fluoride is a compound made of the mineral fluorine combined another substance, like sodium fluoride found in toothpaste. Some fluorides are naturally occurring and most drinking water sources naturally contain at least some; certain countries have notoriously high concentrations, like China and India.
In the 1940s, it was found that communities with higher levels (but not too high) of naturally-occurring fluoride in their drinking water had lower rates of tooth decay. Based on this, it was first added to tap water in the US in 1945, and studies showed a reduction of cavities in school children. Since then fluoride has been added to municipal drinking water across the globe, while at the same time being banned by other municipalities (especially in Europe). The decision to fluoridate tap water lies with individual municipalities in US and Canada – some have opted out of the practice after using it before due to increasing public concern.
It is used to fight cavities topically as well, in toothpastes and other oral hygiene products. It promotes remineralization of areas that have been damaged by the acids that lead to cavities – typically produced by bacteria that form from eating sugary and carbohydrate-heavy foods. Dental associations are pretty unanimous in their support of fluoride in dental care products.
The US FDA and Health Canada have set a maximum fluoride level of 0.7 mg/L in community water to balance the cavity reduction goal with risks of fluorosis – a build up of fluoride that can be minor to severe. [1,2]
To prevent the more severe risk, skeletal fluorosis, the US Environmental Protection Agency (EPA) has set a maximum amount of fluoride allowable in drinking water of 4.0 mg/L. Skeletal fluorosis is when fluoride builds up in the bones resulting in joint stiffness and pain, and can also lead to weak bones or fractures in older adults.
Dental fluorosis, which prevents tooth enamel from forming normally and results in brown spots on the teeth, can be caused by lower concentrations of fluoride. The EPA has a guideline of no more than 2.0 mg/L to help protect children (under the age of 9) from dental fluorosis. This is not an enforceable regulation, but public water systems must tell their customers if the fluoride level goes above it. Health Canada recommends a maximum allowable exposure of no more than 1.5 mg/L.
The Case for Fluoride in Drinking Water
I’ll use Canadian examples here, but American government agencies and dental associations offer similar points.
According to Health Canada, the rate of tooth decay (in permanent teeth) has declined in from 74% of children in 1970-1972 to less than 25% in 2007-2009 as a result of a variety of factors, including widespread adoption of community water fluoridation.  Further, they have not found any compelling link between low doses of fluoride in drinking water and serious health impacts:
“The weight of evidence from all currently available studies does not support a link between exposure to fluoride in drinking water at 1.5 mg/L and any adverse health effects, including those related to cancer, immunotoxicity, reproductive/developmental toxicity, genotoxicity and/or neurotoxicity. It also does not support a link between fluoride exposure and intelligence quotient deficit, as there are significant concerns regarding the relevant studies, including quality, credibility, and methodological weaknesses.” 
Further, community water fluoridation has been shown to save families and the health care system money by reducing tooth decay. 
The case for fluoride is that it offers significant health benefits, and the research hasn’t proven a link between the amount in our drinking water and dental products and any significant health concerns.
The Case Against Fluoride in Drinking Water
One of the primary concerns amongst dental professionals who oppose widespread use of fluoridated water is that maximum dose is based on assumptions of how much water a person drinks. This doesn’t take into account body size, genetics, actual water consumption, or underlying conditions which may be more susceptible to fluoride’s effects such as kidney dysfunction or diabetes. 
Here’s a run-down of some of the main risks associated with fluoride being added to drinking water and other products we use on a regular basis.
Difficulty determining total exposure. The regulatory limits take into account an expected volume of water a person drinks in a day and level of health, along with estimates for fluoride intake from other sources (primarily food and dental products). But it’s impossible to know exactly how much an individual is absorbing. A National Toxicology Program systematic review found that at high exposure levels (4 mg/L), fluoride exposure results in adverse effects on health. How this may reflect a specificity of effect on the nervous system or translates to lower exposure levels remains an important question. 
For context, Toronto water report indicates fluoride concentrations in 2017 ranged from 0.82 – 0.14mg/L,  with the average being 0.58mg/L. Provincial and territorial data from 2005 show levels of fluoride in fluoridated drinking water systems varying from 0.46 to 1.1 mg/L on average across Canada. Over 75% of the Canadian population on a water system are estimated to receive fluoride in their water at concentrations of less than 0.6 mg/L, and fewer than 2% of the population would receive community water at levels over 1.0 mg/L. 
Infant exposure. Infants are particularly vulnerable to toxins, and there is concern that the “one dose fits all” approach to community water fluoridation guidelines doesn’t account for the increased risk of fluoride toxicity in infants. In fact, even Health Canada offers this instruction:
“Before adding water to infant formula, read the label to see if the formula already contains fluoride. If you live in an area with naturally occurring high levels of fluoride (higher than the guideline of 1.5 mg/L- the maximum acceptable concentration), we suggest you mix the formula with drinking water with a lower fluoride concentration level.” 
Underlying health conditions. Urine is a major route of excretion for fluoride taken into the body, and the renal system is essential for the regulation of fluoride levels in the body. If these systems aren’t operating properly, there’s a concern that fluoride can build up more than in an average healthy person. This is particularly concerning for those with kidney disease or diabetes.
Impact on the thyroid. Fluoride easily displaces iodine within the body, and therefore affects the functioning of thyroid gland. Adults with a moderate-to-severe iodine deficiencies and higher levels of urinary fluoride may be at an increased risk for underactive thyroid gland activity. 
For those with existing thyroid hormone concerns, the thyroid stimulating hormone (TSH) output from the pituitary gland is inhibited by fluoride, thus reducing thyroid hormone output from thyroid glands. Fluoride competes for the receptor sites on the thyroid gland which respond to TSH; so that this hormone reaches the thyroid gland and so fewer hormone is manufactured. 
Lack of data. Because skeletal fluorosis can present like other conditions such as arthritis, there is concern that there isn’t enough research to conclude whether it is happening at higher rates than currently thought.
Lead levels in Children. Fluoride, in its form of hydrofluosilicic acid (which is added to many water supplies to fluoridate the water), attracts lead which is common in plumbing pipes. Likely because of the affinity for lead, fluoride has been linked to higher blood lead levels in children.  There is no known safe level of lead for children’s neurological development.
Childhood neurodevelopment. Neurodevelopmental disabilities, including autism, attention-deficit hyperactivity disorder, dyslexia, and other cognitive impairments appear to be on the rise. Some studies link fluoride (at levels potentially found in drinking water though typically higher) with lowered IQ in children, behavioural concerns, and neurological issues [14,15]. Future research should include detailed individual-level information on prenatal exposure, neurobehavioral performance, and covariates for adjustment. 
What about Fluoride in Toothpaste?
Fluoride applied topically can help remineralize the tooth enamel, making it more resistant to decay. The American Dental Association recommends brushing twice a day with a toothpaste containing fluoride  but some dentists don’t think the fluoride concentration in regular toothpaste is enough to do anything. [18,19]
There is little if any research on the absorption of fluoride in toothpaste into the body, so we don’t know how much regular brushing contributes to a person’s total exposure.
It is widely recognized however, that we should not be swallowing toothpaste and children should only be using a very small amount and only if they can completely spit it out.
Is Fluoride Safe: Yes or No?
This comes back to the precautionary principle I mentioned off the top. As you can see, there isn’t a cut-and-dry answer. From my review of the science, and just like so many toxins we’re exposed to on a regular basis, there isn’t unequivocal proof one way or another than the total fluoride we are exposed to is safe.
The precautionary principle states that if a substance has the potential to cause harm, it should be avoided. I subscribe to it for the most part, but it also has its limits. Especially when potential benefits might outweigh the potential risks.
My job isn’t to tell you whether or not you should drink fluoridated water, use toothpaste with fluoride, or accept fluoride-based dental treatments. My job is to provide you with balanced information to help you decide what’s best for you and your family.
Here are some tips to help you implement whatever strategy you decide.
- If you don’t know whether or not your municipality adds fluoride to your water, a quick Google search should be able to tell you. You can also look up test data to see how much is added. If you use formula for your baby, check the fluoride content and compare against your water source’s fluoride concentrations. You may want to choose unfluorinated water to avoid over exposure.
- If you want to avoid drinking fluoridated water, you can install a water filtration system with reverse osmosis. Activated carbon alone (including under counter and pitchers) won’t remove fluoride. Some systems like the Berkey claim to remove fluoride as well, but be sure to look into removal rates and test data.
- If you choose fluoridated toothpaste, make sure you follow the warnings in the fine print, especially for children. Be sure to check the rest of the ingredients and especially avoid triclosan. The Green Beaver Company, for example, makes healthier toothpastes – with and without fluoride.
- Speaking with a biological or holistic dentist (one that is fully licenced) may also help. They tend to approach oral health as part of your overall health and are more likely to be able and willing to answer questions about issues conventional dentists just brush off.
Regardless of which option you take, you can support healthier teeth and help prevent cavities with diet and lifestyle. The obvious dental hygiene recommendations apply; brush your teeth twice a day and floss regularly. But here are some additional tips to keep in mind:
- Reduce sugar intake and carbonated beverages.
- Consume more calcium-rich foods like broccoli, collards, almonds, and kale.
- Promote salivation by eating high-fiber foods like dates, bananas, Brussels sprouts, and peas. Vitamins that can help as well include Vitamin B, D, magnesium and iron.
- Add foods rich in probiotics to support healthy bacteria that prevent plaque and decay. These include kombucha, kefir and fermented foods like kimchee and sauerkraut. These foods.
- If you’re prone to tooth decay and a regular coffee drinker, consider switching to green tea. Coffee creates a pH imbalance that makes a perfect environment for cavity-causing bacteria, whereas green tea contains antioxidants and has several anti-inflammatory properties that can improve oral health.
I hope this helps you make your decision, or at least feel better about one you might have already made!