In 1979, the United States Government implemented the 1976 Toxic Substances Control Act, one part of which restricted the manufacture of PCBs. The same year, Monsanto Corporation, the principal producer of PCBs, releaed a study showing that exposure to dioxin (a major PCB contaminant and breakdown product) did not increase cancer risk1. They also aired public relations commercials featuring the above slogan, so feeble that today it seems they weren't even trying to convince anyone, simply laughing in everyone's faces.
1In
1990, EPA scientists alleged that Monsanto had "fraudulently manipulated" the data for this study.