For the first time in modern American history, a skeptic of medical research could be responsible for safeguarding public health.

Kennedy's condition is called spasmodic dysphonia, which is a neurologic disorder that can affect the voice and speech by causing the muscles that generate a person’s voice to go into periods of spasm, according to Penn Medicine. It is a lifelong condition, but can be improved with treatment in some cases, according to Penn Medicine.

If approved, Kennedy will control a $1.7 trillion agency that oversees food and hospital inspections, hundreds of health clinics, vaccine recommendations and health insurance for roughly half the country.

Robert F. Kennedy Jr. faced aggressive questions about his skepticism of vaccines and other issues during the first of two scheduled Senate confirmation hearings.

Robert F. Kennedy Jr., a former presidential candidate and environmental activist, endorsed Donald Trump last year and threw his weight behind a campaign to “Make America Healthy Again.” For the past two decades he has been best known for airing skeptical views on vaccines.

Robert F. Kennedy Jr. has said vaccines are not safe. His support for abortion access has made conservatives uncomfortable.