 In a later court hearing, however, none of the reasons that were given for the dismissal were found to be substantiated.For years, Velsicol produced polybrominated biphenyls, DDT, cattle feed additives, and various other chemicals at its plant in St. Louis, Michigan.In 1973, a packaging error at the plant resulted in several thousand pounds of PBBs contaminating cattle feed which was later fed to animals across Michigan.