THE NEW(-ISH) FIGHT OVER FLUORIDE

What to know about the controversial mineral in your water and toothpaste.

-  ERICA SWEENEY AND MARTY MUNSON

IF YOU'D LIVED in Grand Rapids, Michigan, in 1945, you'd have been one of the first people in America to sip fluoridated tap water. As of 2024, about 73 percent of us get the mineral in our water supply.

And for almost 80 years, there's been nonstop drama around that addition. In 1956, Clive McCay, a researcher at Cornell University, wrote that water fluoridation "is being considered as a panacea by one party and a poison by another." Yes, it is. Last year, Tik Tok posts described the mineral as "toxic." On X, Health and Human Services secretary appointee Robert F. Kennedy, Jr., called it an "industrial waste" associated with numerous diseases. Dentists and many public health advocates say it's very important for your health.

The controversies haven't always been just about concerns for your teeth and body. Some people object to the government putting anything in the water.

"There is something about water and the necessity of it for our lives that makes people particularly protective of the water supply," explains Catherine Carstairs, PhD, a professor at the University of Guelph in Ontario, who has researched the history of fluoride. "Also, there's a concern that it simply isn't natural to put fluoride in the water, even though, ironically, the benefits of fluoride were discovered because it naturally occurs in many water supplies." So what exactly is it, and what does it have to do with our health?

WHAT FLUORIDE IS

THIS MINERAL, A FORM of the element fluorine, was found to prevent tooth decay and cavities in the early 1900s.

(A dentist in Colorado saw that people whose water naturally had high levels of fluoride also had exceptionally cavity-resistant teeth.) Why it works: The protective outer layer of tooth enamel is made of hydroxyapatite. That starts to break down when it comes into contact with the sugar you eat and the bacteria in plaque that convert the sugar to acid.