Robert F. Kennedy Jr. has often used his influential position to weigh in on public health issues, but during a congressional hearing he dodged questions about whether children should be vaccinated.

From canola oil to colorful dyes, the US food industry is girding for a shift away from the ingredients that made American diets among the cheapest in the world.

Kennedy, who heads the federal government's health department, said his opinions on vaccines were "irrelevant."