Hazardous, or toxic, waste is the potentially dangerous byproduct of a wide range of activities, including manufacturing, farming, water treatment systems, construction, automotive garages, laboratories, hospitals, and other industries. The waste may be liquid, solid, or sludge and contain chemicals, heavy metals, radiation, pathogens, or other materials. Even households generate hazardous waste, from items such as batteries, used computer equipment, and leftover paints or pesticides.