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Does Fluoride in the Water Impact Children’s IQ?

The majority of Americans are exposed to fluoride in water and toothpaste. A new study reports that prenatal exposure may affect young children. What to do?

Ever since fluoride was first added to drinking water in Grand Rapids, Michigan, on January 26, 1945, it has been controversial. The “fluoride wars” have been raging ever since. There is little doubt that when municipal water authorities put fluoride in the water supply, it helps prevent tooth decay.

Are there any downsides about fluoride that people should know about? A new study suggests that children’s IQ may be impacted by early exposure to fluoride in the water (JAMA Pediatrics, online, Aug. 19, 2019).

Dentists and Public Health Officials Love Fluoride:

Although there have been questions about fluoride’s potential toxicity, most public health officials dismiss them. They consider water fluoridation one of the top ten public health achievements of the last century.

The Cochrane Collaboration is an independent collection of scientists and scholars. Cochrane describes itself this way:

“Cochrane is for anyone interested in using high-quality information to make health decisions. Whether you are a doctor or nurse, patient or carer, researcher or funder, Cochrane evidence provides a powerful tool to enhance your healthcare knowledge and decision making.”

Here is what Cochrane says about fluoride in the water to prevent tooth decay (Cochrane Database of Systematic Reviews, June 18, 2015): 

“We carried out this review to evaluate the effects of fluoride in water (added fluoride or naturally occurring) on the prevention of tooth decay and markings on teeth (dental fluorosis).”

“We reviewed 20 studies on the effects of fluoridated water on tooth decay and 135 studies on dental fluorosis. The evidence is up to date at 19 February 2015.

“Our review found that water fluoridation is effective at reducing levels of tooth decay among children. The introduction of water fluoridation resulted in children having 35% fewer decayed, missing and filled baby teeth and 26% fewer decayed, missing and filled permanent teeth.”

“Within the ‘before and after’ studies we were looking for, we did not find any on the benefits of fluoridated water for adults.”

The Flip Side of the Fluoride Debate:

I remember riding in the car with my parents in the 1950s when a radio announcer insisted, with great passion, that fluoridation was a communist plot to make Americans dumber. My parents thought the guy was a total kook. Most Americans agreed.

Over the course of the following decades, two-thirds of U.S. citizens now ingest fluoride in the water. In addition, there is fluoride in toothpaste and mouthwash.

Fluoride and IQ?

A study in JAMA Pediatrics (online, Aug. 19, 2019) suggests that when pregnant women are exposed to higher levels of fluoride, their infants may have lower IQs as they grow up.

The researchers studied 512 mother-child pairs from six Canadian cities. Roughly 40% of them had fluoride in the water. Urine samples during pregnancy measured the mothers’ fluoride exposure. The investigators also estimated exposure based on the women’s reports of their drinking water sources during pregnancy.

They found that women with the highest levels of fluoride in their urine had sons with modestly lower IQ scores at three to four years of age. When the researchers considered total fluoride exposure of the mothers during pregnancy, boys and girls were affected.

Other Fluoride Research:

This is not the first study to suggest that fluoride in water might be neurotoxic for developing brains.

In the JAMA Pediatrics article, the authors point out: 

“Fluoride crosses the placenta, and laboratory studies show that it accumulates in brain regions involved in learning and memory and alters proteins and neurotransmitters in the central nervous system. Higher fluoride exposure from drinking water has been associated with lower children’s intelligence in a meta-analysis of 27 epidemiologic studies and in studies including biomarkers of fluoride exposure.”

What Conclusions Can We Draw?

The authors offer the following summation of their research:

“In this prospective birth cohort study from 6 cities in Canada, higher levels of fluoride exposure during pregnancy were associated with lower IQ scores in children measured at age 3 to 4 years. These findings were observed at fluoride levels typically found in white North American women. This indicates the possible need to reduce fluoride intake during pregnancy.”

Is Fluoride in Water Worrisome?

This study was only about prenatal fluoride exposure. The results are likely to be divisive. The editors of JAMA Pediatrics acknowledged the sensitivity of the topic.

Here is what they said in justifying publication of this research (JAMA Pediatrics, Aug. 19, 2019):

“This decision to publish this article was not easy. Given the nature of the findings and their potential implications, we subjected it to additional scrutiny for its methods and the presentation of its findings. The mission of the journal is to ensure that child health is optimized by bringing the best available evidence to the fore. Publishing it serves as testament to the fact that JAMA Pediatrics is committed to disseminating the best science based entirely on the rigor of the methods and the soundness of the hypotheses tested, regardless of how contentious the results may be.”

What Are Your Thoughts About Fluoride in Water?

We know that this research will be controversial. There is another recent study that adds to concerns about the safety of fluoride in water. Here is a link to fluoride exposure and kidney and liver function in adolescents. 

Please share your thoughts in the comment section. This topic is controversial. Please be thoughtful in your response.

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
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  • Green, R., et al, "Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada," JAMA Pediatrics, online, Aug. 19, 2019, doi:10.1001/jamapediatrics.2019.1729
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