Fluoride is found naturally in soil, water, and foods. It is also produced synthetically for use in drinking water, toothpaste, mouthwashes and various chemical products.
Water authorities add fluoride to the municipal water supply, because studies have shown that adding it in areas where fluoride levels in the water are low can reduce the prevalence of tooth decay in the local population.
Tooth decay is one of the most common health problems affecting children. Many people worldwide cannot afford the cost of regular dental checks, so adding fluoride can offer savings and benefits to those who need them.
However, concerns have arisen regarding fluoride’s effect on health, including problems with bones, teeth, and neurological development.
Fast facts about fluoride
- Fluoride comes from fluroine, which is a common, natural, and abundant element.
- Adding fluoride to the water supply reduces the incidence of tooth decay.
- Fluoride protects teeth from decay by demineralization and remineralization.
- Too much fluoride can lead to dental fluorosis or skeletal fluorosis, which can damage bones and joints.
Excessive exposure to fluoride has been linked to a number of health issues.
Exposure to high concentrations of fluoride during childhood, when teeth are developing, can result in mild dental fluorosis. There will be tiny white streaks or specks in the enamel of the tooth.
This does not affect the health of the teeth, but the discoloration may be noticeable.
Breastfeeding infants or making up formula milk with fluoride-free water can help protect small children from fluorosis.
Children below the age of 6 years should not use a mouthwash that contains fluoride. Children should be supervised when brushing their teeth to ensure they do not swallow toothpaste.
Excess exposure to fluoride can lead to a bone disease known as skeletal fluorosis. Over many years, this can result in pain and damage to bones and joints.
The bones may become hardened and less elastic, increasing the risk of fractures. If the bones thicken and bone tissue accumulates, this can contribute to impaired joint mobility.
In some cases, excess fluoride can damage the parathyroid gland. This can result in hyperparathyroidism, which involves uncontrolled secretion of parathyroid hormones.
This can result in a depletion of calcium in bone structures and higher-than-normal concentrations of calcium in the blood.
Lower calcium concentrations in bones make them more susceptible to fractures.
In 2017, a report was published suggesting that exposure to fluoride before birth could lead to poorer cognitive outcomes in the future.
The researchers measured fluoride levels in 299 women during pregnancy and in their children between the ages of 6 and 12 years. They tested cognitive ability at the ages of 4 years and between 6 and 12 years. Higher levels of fluoride were associated with lower scores on IQ tests.
In 2014, fluoride was documented as a neurotoxin that could be hazardous to child development, along with 10 other industrial chemicals, including lead, arsenic, toluene, and methylmercury.
Other health problems
According to the International Association of Oral Medicine and Toxicology (IAOMT), an organization that campaigns against the use of added fluoride, it may also contribute to the following health problems:
- acne and other skin problems
- cardiovascular problems, including arteriosclerosis and arterial calcification, high blood pressure, myocardial damage, cardiac insufficiency, and heart failure
- reproductive issues, such as lower fertility and early puberty in girls
- thyroid dysfunction
- conditions affecting the joints and bones, such as osteoarthritis, bone cancer, and temporomandibular joint disorder (TMJ)
- neurological problems, possibly leading to ADHD
One review describes fluoride as an “extreme electron scavenger” with an “insatiable appetite for calcium.” The researchers call for the balance of risks and benefits to be reconsidered.
Acute, high-level exposure to fluoride can lead to:
- abdominal pain
- excessive saliva
- nausea and vomiting
- seizures and muscle spasms
This will not result from drinking tap water. It is only likely to happen in cases of accidental contamination of drinking water, due, for example to an industrial fire or explosion.
It is worth remembering that many substances are harmful in large quantities but helpful in small amounts.
Flouride exists in many water supplies, and it is added to drinking water in many countries.
It is also used in the following dental products:
- cements and fillings
- gels and mouthwashes
- some brands of floss
- fluoride supplements, recommended in areas where water is not fluoridated
Non-dental sources of flouride include:
- drugs containing perfluorinated compounds
- food and beverages made with water that contains fluoride
- waterproof and stain-resistant items with PFCs
Excess fluoride exposure may come from:
- public water fluoridation
- high concentrations of fluoride in natural fresh water
- fluoridated mouthrinse or toothpaste
- untested bottled water
- inappropriate use of fluoride supplements
- some foods
Not all fluoride exposure is due to adding the chemical to water and dental products.
Some geographical areas have drinking water that is naturally high in fluoride, for example, southern Asia, the eastern Mediterranean, and Africa.
Possible side effects of excessive fluoride intake include:
- discoloration of teeth
- bone problems
Other possible side effects are listed under the “risks” section above.
The American Dental Association (ADA) says fluoride in water benefits communities because it:
- reduces tooth decay by 20 to 40 percent
- protects against cavities
- is safe and effective
- saves money on dental treatment
- is natural
Studies continue to show that adding fluoride to water supports dental health.
A Cochrane review published in 2015 found that when fluoride was introduced to water:
- Children had 35 percent fewer decayed, missing, or filled baby teeth.
- There was a 15-percent increase in children with no decay in their baby teeth.
- The proportion of children with no decay in their permanent teeth rose by 14 percent.
Applying fluoride on children’s teeth can prevent or slow decay.
How does it work?
Fluoride prevents tooth decay by:
- changing the structure of the developing enamel in children under the age of 7 years, so that it is more resistant to acid attack
- providing an environment where better quality enamel is formed, which is more resistant to acid attack
- reducing the ability of bacteria in plaque to produce acid
This involves the following processes:
Protection from demineralization: When bacteria in the mouth combine with sugars, they produce acid. This acid can erode tooth enamel and damage our teeth. Fluoride can protect teeth from demineralization that is caused by the acid.
Remineralization: If acid has already caused some damage to the teeth, fluoride accumulates in the demineralized areas and begins strengthening the enamel. This is remineralization.
Who benefits the most?
Everyone can benefit from added dental protection, but those who can benefit particularly are people who:
- enjoy snacking
- have poor dental hygiene
- have little or no access to a dentist
- follow diets that are high in sugars or carbohydrates
- have had bridges, crowns, braces, and other restorative procedures
- have a history of tooth decay or cavities
Most public health authorities and medical associations worldwide recommend that children and adults receive some fluoride, to protect their teeth from decay.
Here are some facts supporting the use of fluoride:
- From 2000 to 2004, 125 communities in 36 states of the U.S. voted to adopt fluoridation.
- In the right amounts, fluoride helps prevent dental decay.
- It is similar to adding vitamins to foods.
- Using fluoride in water to protect teeth reduces the need for costly dental procedures.
- Over 100 national and international health and other organizations recognize the benefits of added fluoride.
Here are some arguments against its use, from the IAOMT:
- Fluoride is a neurotoxin which, in high doses, can be harmful.
- Excessive exposure can lead to tooth discoloration and bone problems.
- There is enough fluoride in the water already, without adding more.
- People have the right to choose whether or not they take medications.
- Different people need different amounts of substances such as fluoride.
- Current levels of fluoride in the water may not be safe.
- It may be harmful for the environment.
The controversy continues over whether it is a good idea to add fluoride to water or not.
In 2000, German researchers reported that tooth decay fell in cities where fluoride ceased to be added to the water.
However, they called for further investigation into the reasons for this decline, which they said could be due to improved attitudes toward dental health and easier access to dental health products, compared with the years before fluoride was added.
They suggested that their findings might support the argument that caries can continue to fall if the concentration of fluoride is reduced from 1 part per million (ppm) to below 0.2 ppm.
How much fluoride is recommended?
The Department of Health and Human Services (DHHS) sets the optimal level of fluoride for preventing tooth decay at 0.7 ppm, or 0.7 milligrams (mg) in every liter of water.
The previous figure, in force from 1962 to 2015, was 0.7 to 1.2 ppm. In 2015, it was revised to the lower limit.
The aim of this optimal level is to promote public health.
What does the WHO say?
The World Health Organization (WHO) notes that long-term exposure to drinking water that contains more than 1.5 ppm fluoride can lead to health problems. The WHO’s guideline limit is 1.5 ppm.
How much does the EPA allow?
The Environmental Protection Agency (EPA) aims to protect people from over-exposure to toxic chemicals.
It sets the maximum allowable level at 4 ppm, and a secondary maximum level at 2 ppm. People are asked to inform the EPA if levels are above 2 ppm. Levels above 4 ppm could be hazardous.
In areas where water naturally contains higher levels of fluoride, community water systems must ensure that the maximum level is no higher than 4 ppm.
As with any substance, excess intake or exposure can be harmful.
It is important not to use any fluoride supplements without first speaking to a dentist.