One word: plastics. Well, it's those and greases and lubricants and the rest of DuPont's messy chemical products, actually, that have landed the company atop the PERI Toxic 100 Index-a list of the top corporate air polluters.
Rounding out the top five are Nissan Motor, Archers Daniel Midland (who also just pulled their support from The News Hour), Bayer Group, and Dow Chemical.