Velsicol Chemical Corporation is an American chemical company based in Rosemont, Illinois that specializes in chemical intermediates for applications such as agrochemicals. It was founded in 1931 by Joseph Regenstein and Julius Hyman. When, in 1962, the landmark anti-pesticide book Silent Spring was first published, Velsicol was the sole manufacturer of two pesticides – chlordane and heptachlor – featured prominently within it. Subsequently, these pesticides were banned. At the time, Velsicol threatened legal action against Silent Springs publisher Houghton Mifflin, though ultimately no such action was taken. 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. When the error was finally recognized, all the cattle in the state were culled. The site of the St. Louis plant is now one of the costliest superfund sites in America.