For decades, fluoride was treated as untouchable. Add it to water. Put it in toothpaste. Give it to children. The message was simple: it prevents cavities, and it’s safe.

That certainty is now cracking.

A growing number of scientists, toxicologists, and public health officials are asking whether fluoride’s risks have been underestimated, especially for children, pregnant women, and people with long-term exposure.

The Brain Is the Biggest Concern

One of the strongest warnings comes from Professor Philippe Grandjean, an environmental health expert at Harvard University. Grandjean has spent years studying chemicals that affect brain development.

He has repeatedly warned that fluoride may interfere with early brain development, placing it in the same category of concern as other developmental neurotoxins.

Several large studies reviewed by U.S. government scientists have found associations between higher fluoride exposure during pregnancy and lower IQ scores in children. These findings do not claim fluoride instantly damages the brain, but they raise serious red flags.

Regulators Are Pulling Back

In recent years, concern has moved beyond academic journals.

The U.S. Food and Drug Administration announced plans to remove ingestible fluoride prescription products for children from the market. These products, meant to be swallowed, were never evaluated using modern drug safety standards. The FDA cited concerns about systemic exposure and possible effects on gut health and development.

At the state level, Utah became the first U.S. state to ban the addition of fluoride to public drinking water. Florida followed with restrictions on chemical additives in water systems. Supporters of these decisions argue that public health should not rely on mass medication without individual consent.

More Than a Dental Issue

Fluoride does not remain on the surface of teeth. Once ingested, it circulates through the body and accumulates in bones. Long-term exposure to high levels has been linked to skeletal fluorosis, a painful condition that stiffens joints and weakens bones.

Some researchers have also raised concerns about fluoride’s interaction with the thyroid, especially in populations with iodine deficiency. Since the thyroid plays a role in metabolism and brain development, this has added to calls for caution.

Industrial Sources and Exposure Questions

Another issue gaining attention is the source of fluoride used in public water systems. The compounds are often industrial byproducts rather than pharmaceutical-grade substances. Critics argue that these additives can contain trace amounts of heavy metals and that the long-term effects of cumulative exposure remain underexplored.

A Shift in Public Health Thinking

Former EPA scientist Dr. Kathleen Thiessen has argued that fluoride safety standards were set decades ago and may not reflect current scientific understanding. She has emphasized that infants and children may be exposed to higher doses per body weight than adults.

The debate over fluoride now mirrors earlier public health reversals involving substances once considered safe, such as lead and asbestos.

Where the Debate Stands

Fluoride remains effective in preventing tooth decay, and many dental professionals continue to support its use. However, an increasing number of experts argue that topical use, such as toothpaste that is not swallowed, may offer benefits without the risks associated with ingestion.

The conversation is no longer about fear or conspiracy. It is about evidence, exposure, and informed choice.

Fluoride’s future in public water and consumable products is no longer guaranteed. And for the first time in decades, science is openly questioning whether its benefits truly outweigh its risks.