This week, we offer the second of a two-part series on the pros and cons of water fluoridation. Last week we discussed the practice of adding fluoride to drinking water to prevent tooth decay. This week we hear from a researcher who has found that early exposure to fluoridated water may affect youngsters’ IQ.

You could listen through your local public radio station or get the live stream at 7 am EDT (February 15, 2025) on your computer or smart phone (wunc.org).  Here is a link so you can find which stations carry our broadcast. If you can’t listen to the broadcast, you may wish to hear the podcast later. You can subscribe through your favorite podcast provider, download the mp3 using the link at the bottom of the page, or listen to the stream on this post starting on February 17, 2025.

More About the Pros and Cons of Water Fluoridation:

Some people are opposed to any municipality putting fluoride in its water supply simply because it means the residents have little choice but to use it. On the other hand, many people embrace a “no harm, no foul” philosophy. What are the potential cons of water fluoridation?

Is Fluoride a Neurotoxin?

Dr. Bruce Lanphear studied the effects of lead on children’s developing brains for decades. There is no longer any doubt that lead harms their intellectual capacity. When someone asked him about fluoride, he realized that he did not know what the potential impact on infants might be. He took advantage of an opportunity to study it, and what he and his colleagues found is rather alarming (JAMA Pediatrics, Aug. 19, 2019).

There were 512 pairs of mothers with their babies in the study, which evaluated fluoride in drinking water and also tested the mothers’ urine during pregnancy. As the levels of fluoride rose, the IQ scores of the boys, tested between age three and four, dropped. Girls did not demonstrate such an association.

The Cons of Water Fluoridation:

We encounter fluoride in toothpaste, in medications and in food packaging, among other sources. However, water fluoridation is far and away the main source of fluoride. As a result, if a community decided that the cons of water fluoridation outweigh the benefits, it would be relatively easy to lower levels for everyone. Simply stop adding fluoride to the water!

Interactions That Could Cause Trouble:

Iodine:

Another disquieting discovery from Dr. Lanphear’s research is that there are multiple interactions among the various compounds we encounter every day. For example, little boys whose mothers were able to get access to adequate iodine during pregnancy were much less likely to suffer IQ deficits than those whose mothers did not have adequate iodine (Science of the Total Environment, April 15, 2023).  Hypothyroidism may be an important link.

Lead:

Another interaction is with lead. Not only does lead itself harm children’s brains, it appears to be a risk factor for tooth decay. Would that lead parents to increase the fluoride exposure for their youngsters? How do lead and fluoride interact in the body? We don’t yet have answers for these important questions.

Pesticides:

In addition, women exposed to higher levels of pesticides are more likely to give birth to children with autism if their folate levels are subpar. That is another area where researchers are striving to learn more about interactions that put babies at risk.

During the interview, we mentioned a recent meta-analysis of 74 studies of water fluoridation. You can find it in JAMA Pediatrics (Jan. 6, 2025).  As with the study Dr. Lanphear describes, children exposed to higher levels of fluoride as measured in their pregnant mothers’ urine were more likely to have deficits in IQ.

The Precautionary Principle:

We asked Dr. Lanphear about the precautionary principle applied by European regulators. He suggested that it is easier to understand when stated as the medical precept, “First, do no harm!” The idea is that we should know as much as possible about hazards as well as benefits of new compounds before broad populations are exposed to them.

This Week’s Guests:

Gary D Slade, BDS, DDPH, PhD, is the John W. Stamm Distinguished Professor of Dentistry at the University of North Carolina Adams School of Dentistry in Chapel Hill, NC. He conducts epidemiological studies of oral diseases including public health interventions for prevention of dental decay. His website is https://dentistry.unc.edu/people/gary-slade/ Dr. Slade was the featured guest in last week’s episode emphasizing the benefits of water fluoridation.

Bruce Lanphear, MD, MPH, is Professor of Health Sciences at Simon Fraser University in Burnaby, BC. He is the featured guest this week on our episode examining the cons of water fluoridation. His website is https://www.sfu.ca/fhs/about/people/profiles/bruce-lanphear.html
Professor Lanphear’s research, at the intersection of preventive medicine, pediatrics, public health, toxicology, and infectious disease, is driven by a commitment to prevent death, disease, and disability. He has published over 350 peer-reviewed studies about the impact of toxic chemicals on intellectual deficits, behavioral problems, and brain structure in children. He is ranked among the top 1% of most-cited scientists globally. Bruce and his brother, Bob, co-founded Little Things Matter to make the science on toxic chemicals publicly accessible. They produce videos to show how human health is inextricably connected with exposures to toxic chemicals and to elevate efforts to prevent disease.

Listen to the Podcast:

The podcast of this program will be available Monday, February 17, 2025, after broadcast on Feb. 15. You can stream the show from this site and download the podcast for free.

Download the mp3, or listen to the podcast on Apple Podcasts or Spotify.