President-elect Donald Trump has picked Robert F. Kennedy Jr. as his Health and Human Services secretary and while we don’t know what the policies will be, one thing Kennedy has signaled he would look at is fluoridation of water across the United States.

Fights are cropping up nationwide over fluoride in drinking water. Communities in Florida, Texas, Oregon, Utah, Wyoming and elsewhere have debated the idea in recent months.

Here's everything you need to know about the benefits and the risks of this common but controversial natural element.