Hazardous waste is any solid, liquid, or gaseous waste material that may pose substantial hazards to human health and the environment if improperly treated, stored, transported, disposed of, or otherwise managed. Every industrial country has had problems with managing hazardous wastes. Improper waste management has necessitated expensive cleanup operations in many instances. Efforts are under way internationally to remedy past problems caused by hazardous waste and to prevent future problems through source reduction (eliminating hazardous wastes at the source), recycling, treatment, and proper disposal of hazardous wastes.