Fluoride Action Network

NAS Fluoride Panelists: Science Is Not on the Side of Fluoridation

May 22nd, 2013

The successful campaign against fluoridation in Portland, Oregon, was based on a growing body of science indicating that fluoride, even at relatively low dosages, can cause serious harm, including thyroid disease, neurological disorders, and bone damage. In response to claims by fluoridation proponents that no valid science supports these concerns, two of the scientists (Dr. Hardy Limeback and Dr. Kathleen Thiessen) that wrote the National Academy of Sciences’ (NAS) prestigious review on fluoride wrote to set the record straight.  In the following two letters (written in March 2013), Drs. Limeback and Thiessen recommended that Portlanders look past the hype and vote NO to fluoridation. Portlanders listened to this advice and soundly rejected fluoridation by a 60%/40% margin.

Letter from Dr. Hardy Limeback


Hardy Limeback, DDS, PhD

I’m the former head of preventative dentistry at the University of Toronto. In addition to being a dentist, I’m a scientist who has spent decades studying the effects of fluoride on teeth and bones.

Based on my work, I was one of 12 scientists in North America chosen to serve on the National Academy of Science’s committee that produced the 2006 report Fluoride in Drinking Water. Taking three years to complete, it’s considered the most comprehensive work ever done on the toxicity of fluoride.

I was trained in traditional dentistry, and for many years accepted the prevailing opinion of the establishment in Canada and the U.S. that water fluoridation is effective and safe.

I was mistaken.

As I intensively studied the literature and performed my own research, the evidence clearly demonstrated that fluoridation is more harmful than beneficial. In 1999, I publicly changed my position. In doing so, I joined the governments and experts throughout the world that DO NOT support fluoridation.

 Why do so many dentists and others in the U.S. and Canada support it? I can’t speak for any individual, but I believe most haven’t reviewed the literature, especially on health risks. And if you speak out against fluoridation, you risk being criticized and shunned by your peers. I know many dentists and physicians who oppose it but won’t take a public stance.

In Canada, citizens all over the country, reviewing much of the same science I did, are opposing it. In just the last five years, the percent of Canadians drinking fluoridated water has dropped from 45% to 32%. Small towns and large cities, including Quebec City, QE, Windsor, ON and Calgary, AL, have voted to ban fluoridation.

For the sake of your health and your children’s health, I urge all citizens of Portland to vote no on Measure 26-151.

Hardy Limeback, DDS, PhD

Dr. Kathleen Thiessen

Kathleen Thiessen, PhD

Fluoridation of drinking water is strongly encouraged by public health agencies and dental organizations to prevent dental caries. However, several important concerns have not been adequately addressed:

Available data show no benefit of fluoridation in improving dental health.

Most studies showing benefits of fluoridation are neither random nor blind. The reported benefits are small, and alternative explanations (fluoride-induced delay in tooth eruption, socioeconomic effects) have not been explored.

Caries rates have declined in all developed countries, fluoridated or not. The CDC indicates that fluoride’s predominant effect on teeth is topical, not from ingestion.

The only U.S. study to examine caries experience in relation to individual fluoride intakes found no association. The most recent (1986-1987) national data set in the U.S. shows no significant difference in caries rates with different water fluoride levels.

Various adverse health effects are associated with fluoride exposures.

Well-known adverse health effects from fluoride exposure include dental fluorosis, skeletal fluorosis, and increased risk of bone fracture. Additional adverse effects include carcinogenicity, genotoxicity, reduced thyroid function, other endocrine effects, neurotoxicity, hypersensitivity, and increased blood lead levels in children. Dental fluorosis is associated with increased risks of thyroid disease, lowered IQ, and bone fracture. “Safe” levels of fluoride exposure are well below the levels experienced with fluoridation, especially for formula-fed infants and people with high water consumption or kidney disease. Minority and low-income populations may have increased risks of adverse effects.

By fluoridation of drinking water, governments and water suppliers are indiscriminately administering a drug to the population, without individual evaluation of need, correct dose, effectiveness, or side effects.

Fluoride tablets require a prescription. Fluoride in toothpaste is a nonprescription drug. Many people consume more fluoride from drinking water than from nonprescription or prescription sources.

Portland voters can best promote their population’s health by voting against water fluoridation.

Kathleen Thiessen, Ph.D.
Coauthor of the National Academy of Science’s 2006 report, Fluoride in Drinking Water