Is fluoride unsafe?

By February 15, 2023 Health, Science

A recent Instagram post, by a holistic health clinic based in the United States (US), claims that fluoride is a neurotoxin and emphasises that it is important to find fluoride-free options for dental care and water.

Further, the post also claims that fluoride affects one’s thyroid function, pineal gland function, bone structure, and IQ and leads to an increased risk of cancer.


Is fluoride a neurotoxin? What is a neurotoxin?

A neurotoxin is a substance that alters the function of the nervous system. It might lead to, among others, limb weakness, loss of vision, and possibly death.

The extent to which a neurotoxin is harmful to humans depends on several factors such as the frequency of contact with a neurotoxin and the concentration of neurotoxin that one has been exposed to. For example, Vitamin A which is an essential nutrient for humans could be a neurotoxin in large doses. Similarly, fluoride can be toxic in high doses.

The most common sources of fluoride are dental products and drinking water containing added fluoride due to its beneficial effects on teeth, such as preventing tooth decay. However, small amounts of fluoride can naturally be found in foods such as meat, vegetables, and canned fish.

Is fluoride unsafe?

In support of its claims on the dangers of fluoride, the Instagram post refers to a study titled “Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis” (“the study”).

The study which was published in 2012 found that children with high-fluoride exposure had lower IQ scores than children with low-fluoride exposure, suggesting that high-fluoride exposure affected children’s neurodevelopment.

Upon closer look, the research seemed to have looked at studies mainly from China where fluoride is commonly found in drinking water as a contaminant.

According to the study, numerous rural communities in China had well water with high fluoride concentrations, substantially above 1 mg per litre of water (1mg/L). In comparison, fluoride concentrations in community water in other industrialised countries were usually 1 mg/L or less, even when fluoride had been added to water supplies as a public health measure to reduce tooth decay.

In particular, multiple case studies of high fluoride exposure in China which were considered for the study looked at drinking water containing fluoride concentrations of 4mg/L or more. In contrast, the World Health Organisation’s (WHO) guideline value for fluoride in drinking water is 1.5mg/L, and even then, WHO advises the value to be adjusted according to local conditions such as volume of water consumption.

An updated review of the study similarly considered case studies with high fluoride levels, often exceeding the WHO guideline, in support of its finding that high fluoride levels affect the IQ levels of children.

Therefore, the study does not support the blanket statement that fluoride is unsafe and will affect the IQ of people.

What about the other claims about fluoride?

Fluoride & bone structure

It is recognised that if someone is constantly exposed to fluoride levels higher than 4mg/L, it can cause skeletal fluorosis, a condition in which fluoride builds up in the bones. Skeletal fluorosis could lead to joint stiffness and weak bones or fractures in older adults.

However, this condition is common in countries where potable water sources contain high fluoride levels. In the US and Singapore, fluoridation of community water supply is generally kept to 0.7mg/L.

Fluoride & thyroid function

High fluoride concentrations have been associated with hypothyroidism, but it could allegedly be mitigated with enough iodine intake. Nonetheless, more research is required to conclusively say whether fluoride affects one’s thyroid function and whether increased iodine intake could offset the effects of fluoride on thyroid function.

Fluoride & pineal gland function

The pineal gland is a small gland in the brain and is a source of melatonin. Melatonin is a hormone that regulates the body’s circadian rhythm and in turn, helps to maintain a regular sleep cycle.

One possible factor in the age-related decline of melatonin is the accumulation of calcium deposits in the pineal gland. Among the various factors that could affect the number of calcium deposits in the pineal gland, fluoride is one factor. Higher levels of fluoride have been associated with increased calcium deposits although a strong causal link has not been established.

Fluoride & cancer

Although studies have been conducted to establish if high fluoride intake leads to cancer, most are retrospective, such as comparing cancer rates in communities before and after water fluoridation was implemented. As other variables could affect the cause of cancer, no causal link has been established between high fluoride intake and increased cancer risk.

In summary, fluoride can be toxic in large doses but there is insufficient evidence that the current levels of fluoride intake across the population, especially in developed countries, is at an unsafe level. More research is required on the potentially harmful effects of fluoride intake, at current levels, across developed countries. Hence the claim that fluoride is a neurotoxin or poison and is therefore unsafe is misleading and false.

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