What Does a Body Good?

"Food Babe" Vani Hari and her legion of fans have managed to get the "yoga mat" out of Subway sandwiches and the synthetic coloring out of Kraft's macaroni & cheese by petitioning these large companies to modify their formulas. But since all food is comprised of chemicals, knowing the difference between a hazardous chemical and a non-carcinogenic one is imperative. Bob speaks with Michelle Francl, a professor of chemistry at Bryn Mawr College and blogger at The Culture of Chemistry and Slate, about what "Food Babe" may be getting wrong.