Major study finds fluoride in drinking water lowers children’s IQ… as map reveals US neighborhoods at risk

Drinking water treated with fluoride can lower children’s IQ, according to a major review that builds on a growing body of research.

The new research looked at 74 other studies exploring how the mineral affects children’s brain development.

It found a strong association between higher levels of fluoride in tap water and lower IQ scores — for every small increase of fluoride found in kids’ urine, there was a decrease of 1.63 IQ points.

The researchers said that while this may seem like a relatively small dip in IQ, ‘research on other neurotoxicants has shown that subtle shifts in IQ at the population level can affect people who fall within the high and low ranges of the population’s IQ distribution.’

They continue: ‘For context, a 5-point decrease in a population’s IQ would nearly double the number of people classified as intellectually disabled.’  

It comes after a US government report found hundreds of thousands of American children are drinking from tap water that may be lowering their IQs.

Robert F Kennedy Junior, who has been nominated as head of the Health and Human Services (HHS), has signaled he plans to remove fluoride from American drinking water due to these concerns. But there is debate about whether the risks would outweigh the benefits. 

Fluoride has been added to the US water supply for decades to strengthen teeth and reduce cavities — in what has long been considered one of the greatest public health achievements of the 20th century.

The above shows the most recently known levels of fluoride in US county water systems

Estimates suggest that fluoridation saves $6.5billion every year in dental treatment costs, and reduces the occurrence of cavities by up to 25 percent — according to the CDC. 

America’s Environmental Protection Agency (EPA) says fluoride levels should not exceed 4 mg/L in water, warning any higher levels raise the risk of skeletal fluorosis, or deformities in the skeleton.

However, a growing swell of research has emerged in the last few years showing water fluoridation may have some cripplingly dangerous side effects, particularly for children’s brains. 

In the new meta-analysis, researchers led by Kyla Taylor of the National Institute of Environmental Health Sciences, reviewed 74 studies from around the world on the link between fluoride and IQ.

The studies were out of China, Canada, Denmark, India, Iran, Mexico, New Zealand, Pakistan, Spain, and Taiwan.

In one study out of Mexico, children’s IQ scores dropped as much as 7.22 following fluoride exposure.  

Based on the findings, the authors say that this risk should not be ignored, and that more research on fluoride’s impact on the developing brain is warranted. 

The researchers note that water and water-based beverages are the main source of systemic fluoride intake. 

They also highlight that there are areas of the US where the amounts exceed recommendations. 

They write: ‘Of note, there are regions of the United States where community water systems and private wells contain natural fluoride concentrations greater than 1.5 mg/L,120 serving more than 2.9 million US residents.

‘In addition, the US Geological Survey estimates that 172,000 US residents are served by domestic wells that exceed EPA’s enforceable standard of 4.0 mg/L fluoride in drinking water, and 522 000 are served by domestic wells that exceed EPA’s non-enforceable standard of 2.0 mg/L fluoride in drinking water.’

To reduce risk of moderate-to-severe dental fluorosis, the CDC recommends that parents use an alternative source of water for children aged eight years or younger and for bottle-fed infants if their primary drinking water contains greater than 2 mg/L of fluoride.

In the US, the Centers for Disease Control and Prevention (CDC) estimates that water and processed beverages (eg, soda and juices) provide approximately 75 percent of a person’s fluoride intake, and EPA estimates that 40 percent to 70 percent of a person’s fluoride intake comes from fluoridated drinking water.

However, an individual’s total exposure also reflects contributions from fluoride in other sources, such as food, dental products, industrial emissions, and pharmaceuticals. 

This map, from 2020, shows fluoride levels in untreated groundwater supplies. Fluoride is a naturally-occurring mineral and is often already present in many water supplies. Areas marked with a yellow or red dot have more than twice the level of fluoride in groundwater than recommended

One 2006 report from the National Research Council (NRC) concluded that high levels of naturally occurring fluoride in drinking water may be of concern for neurotoxic effects.

And studies since have looked at how fluoride exposure may affect brain development. 

The findings come just weeks after a top doctor  urged pregnant and breastfeeding women to avoid drinking tap water that contains fluoride because the mineral could damage fetuses’ brains. 

Dr Michael Greger, author of the How Not To Die series, said even parents who feed their children formula should avoid mixing it with water treated with fluoride, which he called a ‘presumed developmental neurotoxin.’

Speaking to DailyMail.com, he said: ‘Pregnant and breastfeeding women and those with infants who are getting water mixed with infant formula should try to go out of their way to use unfluoridated water.’

His comments came days after a federal judge warned that fluoride, added to water systems to strengthen teeth and reduce cavities, posed an ‘unreasonable risk’ to children’s brains.

Far more counties in the US fluorinate their water than in any other country in the world, data from the National Population Review for the year 2024 reveals

And just a month after a 320-page government report found fluoride in high concentrations could lead to children’s IQ dropping by up to five points.

Experts say when someone drinks water that contains fluoride, the chemical enters the bloodstream and can then travel to the brain. 

Hypotheses suggest the fluoride could then interfere with the brain during development leading to children having a lower IQ. 

It is also possible for it to cross the placental barrier and reach a fetus, where it could also disrupt brain development.

Additionally, experts say it is possible for the fluoride to enter breastmilk and be transferred to an infant. 

Dr Greger said it was also possible that fluoride was impacting the brain health of adults, but that more studies were needed to determine this.