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.

A chemical byproduct found in some treated drinking water in the U.S. that remained a mystery for more than 40 years may have finally been identified by scientists. The authors of the study, published Thursday in the journal Science,

The international research team behind the discovery is advocating rapid assessment of its potential toxicity.