United States Toxic Substances Control Act. "The Toxic Substances Control Act, signed into law in 1976, provides EPA with broad authority to regulate chemicals and chemical substances whose manufacture, processing, distribution in commerce, use or disposal may present an unreasonable risk of injury to health and the environment. TSCA covers all chemicals planned for production, manufactured, imported, or exported from the United States except pesticides, tobacco (or tobacco products), source material by-products or special nuclear material defined by the Atomic Energy Act and food, food additives, drugs and cosmetics covered under the Federal Food, Drug and Cosmetic Act."