The Link Between Fluoride in Water and ADHD: Should You Be Concerned?

New Findings Suggest Fluoride Connected to An Increased Rate of ADHD in Children

For decades, health experts have disagreed as to whether artificially fluoridated water is toxic to the developing human brain. While extremely high levels can cause dental and skeletal fluorosis, it can also cause neurotoxicity in adults.

Far less, however, is known about the impact on children's’ developing brains.  

What is Fluoride?

All water contains some fluoride. Naturally occurring in water, soil, rocks ,and air, fluoride is a mineral also found in your bones and teeth. There have been numerous studies championing the benefits of fluoride on dental health and many U.S. water systems intentionally add fluoride to the drinking water supply.

While fluoride has been added to drinking water for upwards of 70 years in the United States, fluoride has come into the hot seat in recent years. A study published in the Journal Environmental Health found that areas with a higher proportion of artificially fluoridated water also had a higher prevalence of attention deficit hyperactivity disorder (ADHD) in children.

Additionally, a University of Toronto study suggests that higher levels of urinary fluoride during pregnancy are associated with an increase in ADHD-like symptoms in young children.

This begs the question: How concerned should you be about fluoride in drinking water?

What is Artificial Water Fluoridation?

Artificial water fluoridation is the practice of adding low concentrations of fluoride–0.7 parts per million (ppm)–to drinking water with the goal of improving dental health. Despite no legal mandate to fluoridate water, nearly 75% of the U.S. population of people had access to fluoridated water. It is widely considered to be a major factor in the 25% decrease in rates of tooth decay in the United States. While hailed as “one of public health’s greatest success stories” by some, the addition of fluoride to drinking water has always had its skeptics, and some people are downright opposed.

What Does Research Suggest about the Risks of Fluoride?

Since a popular study on fluoride and neurodevelopment began in 1992, the percentage of the U.S. population that drinks fluoridated water has increased from 56 percent to nearly 70 percent. During that same time frame, the percentage of children with an ADHD diagnosis has increased from around seven percent to more than 11 percent.

Additionally, the 2018 University of Toronto study included the analysis of urine from women during pregnancy, as well as from their children from ages six to 12. Researchers examined how levels of fluoride in urine related to the children’s inattention and hyperactivity. After adjusting factors that impact neuro-development (such as gestational age at birth, birth-weight, birth order, sex, maternal marital status, smoking history, age at delivery, education, socioeconomic status and lead exposure), researchers were able to assign scores related to ADHD. They concluded that prenatal exposure to fluoride was associated with an increased frequency of inattentive behaviors and cognitive problems.

Finally, upwards of 40 studies show that children born in areas with elevated concentrations of fluoride (i.e. above the concentration typically used in U.S. public water system), have lower than average IQs. In fact, many studies demonstrate a significant link–showing that children in high fluoride areas had IQs that were seven points below those of children from areas of low concentrations of fluoride.

How Might Fluoride Increase the Prevalence of ADHD in Children?

The studies mentioned above suggest an association between fluoride and ADHD, however they do not prove causality. The question becomes, how might fluoride increase the prevalence of Attention-deficit/hyperactivity disorder? Below are some possible links:

Fluoride and Fluorosis:

Several studies suggest that children with moderate to severe fluorosis–i.e. The change in the appearance of tooth enamel due to excessive fluoride intake–can lead to a lower score on IQ tests and other measures of cognitive skills. According to a report by the Center for Disease Control  (CDC) suggests that 41% of Americans ages 12 to 15 have some form of fluorosis.

Fluoride and Lead Absorption:

The form of fluoride typically added to U.S. water supplies (fluorosilicic acid) can leach lead–a potent neurotoxin–from pipes. Research has shown that fluoride may increase the body’s ability to absorb lead and children in regions with highly fluoridated water frequently have elevated blood lead levels. Lead has been shown to play a role in ADHD.

Fluoride and Thyroid:

It’s been proven that fluoride impairs the activity of the thyroid gland, which is important for proper brain development.

Not Everyone Agrees on the Link Between Fluoride and ADHD

These findings have led many people to advocate against fluoride, however others were also eager to point out that this is just one study and may not definitively prove the causal link between fluoridation and ADHD. Limitations on the study include: