Are food preservatives bad for you? - Eleanor Nelsen

Food doesn't last. In days, sometimes hours, bread goes moldy, apple slices turn brown, and bacteria multiply in mayonnaise. But you can find all of these foods out on the shelf at the grocery store — hopefully unspoiled -- thanks to preservatives. But what exactly are preservatives? How do they help keep food edible? And are they safe? Eleanor Nelsen investigates.