Bill Nye, an engineer best known for his 1990s TV show “Bill Nye the Science Guy,” panned Robert F. Kennedy Jr.’s selection as the incoming Trump administration’s top health official.

“I think he’s lost his way,” he said on Wednesday while speaking to reporters in the Capitol.

Nye touted the benefits of fluoride in cavity prevention, noting that he believes his dental health is better because the mineral is added to drinking water supply, in Washington, D.C., where he grew up. Kennedy has said he wants the mineral, which occurs naturally but may be added by state or local governments, out of drinking water.

Nye, an advocate for the National Ataxia Foundation, said he was in the Capitol “trying to get the FDA just a bit of a nudge” to consider data around a potential treatment for spinocerebellar ataxia, a group of inherited brain disorders that affects physical coordination and loss of fine motor skills. The genetic condition runs in Nye’s family.

Nye seemingly nodded to Kennedy’s unfounded claims about the safety of vaccines.

“His other claims are extraordinary, and I really hope somebody will reconsider his position,” he said.