St. Louis is the site of the former Michigan Chemical Corporation plant, which helped market and produce DDT as a widely commercial product. After its purchase by Velsicol Chemical Corporation, the plant was responsible for a product mixup in the 1970s. This resulted in contamination of cattle feed with PBB, a flame retardant. The feed was distributed throughout Michigan and the Midwest. The mixup occurred due what was described as a "triple witching hour" of events: a labor strike with management's replacing regular workers; a shortage of bags that helped distinguish between cattle feed additive and the flame-retardant PBB; and storing both the cattle feed and the fire retardant in the same dimly lit warehouse.