With President-elect Donald Trump in the White House, the 21st century may be another story. Robert F. Kennedy Jr., whom Trump has pledged to let “go wild” on public health under his administration, is an outspoken opponent of adding fluoride to drinking water. He intends to take action.

Kennedy Jr. has previously said that if Republican President-elect Donald Trump won the White House, the administration would advise water systems in the United States to remove fluoride. This is despite experts and officials saying the mineral is both safe and beneficial to people’s dental health.

Robert F. Kennedy Jr.'s recent comments on fluoride are prompting questions about its safety in drinking water. Here's what to know.

For years, local water authorities have considered the addition of low concentrations of fluoride to drinking water a public health achievement. The Centers for Disease Control and Prevention recommends it, citing evidence showing that fluoride prevents cavities in children — the No. 1 chronic disease in kids.

The CDC calls the practice of adding fluoride to tap water systems one of the 10 greatest public health achievements of the last century.

"On January 20, the Trump White House will advise all U.S. water systems to remove fluoride from public water. Fluoride is an industrial waste associated with arthritis, bone fractures, bone cancer, IQ loss, neurodevelopmental disorders, and thyroid disease," Kennedy said on social media over the weekend.

Former President Donald Trump on Sunday expressed tentative support for Robert F. Kennedy Jr.’s plan to order the removal of fluoride from water supplies during a potential second Trump term, saying that it “sounds OK to me.