For 80 years, most Americans have been drinking tap water that contains fluoride. A small amount of this compound is added to community water supplies to strengthen teeth and prevent cavities. But this past May, Utah became the first U.S. state to ban fluoridated drinking water. Florida followed suit in July.
To understand the impact this could have on residents, researchers studied cities that had previously banned fluoridated water, like Calgary, Canada. One study found that 65 percent of Calgary second-graders had one or more cavities compared with 55 percent in the nearby city of Edmonton, which has fluoridated water.
Some opponents of fluoride cite studies that link health problems to consuming large amounts of the chemical. But just “a tiny amount is optimal to help protect your teeth from decay,” says Dr. Bina Katechia, a dental professor at the University of Connecticut.