What is sarsaparilla and why is it no longer used in root beer floats?

Sarsaparilla was made from the Sarsaparilla vine, while Root Beer, roots of the sassafras tree. These days, Root Beer recipes do not include sassafras as the plant has been found to cause serious health issues. The vine was banned by the American Food and Drug Administration for commercial food production in 1960.

more here: https://www.bundaberg.com/en-us/the-difference-between-root-beer-and-sarsaparilla/#:~:text=Sarsaparilla%20was%20made%20from%20the,commercial%20food%20production%20in%201960.