Fluoridated drinking water has been hailed as one of the top 10 public health achievements of the 20th century by the Centers for Disease Control and Prevention (CDC). But it’s also a practice that new health secretary Robert F. Kennedy, Jr. has said should be halted.  This week, Utah appeared to heed his warnings, as Republican Gov. Spencer Cox signed legislation late Thursday that banned fluoride in public drinking water across the state, making it the first state to do so.  “We don’t need fluoride in our water. It’s a very bad way to deliver it into our systems,” Kennedy had asserted the day after the November election to NPR on Morning Edition. Below, a primer on fluoride in drinking water, its history of controversy, and what the science says.