Hazardous waste can be a liquid, solid or sludge that is a by-product of a manufacturing process.
I can also be a commercial product like battery acid or industrial solvents that are discarded. Waste that if improperly managed can contaminate groundwater and be harmful or fatal to humans. A broad range of wastes that are unstable, explosive or can create toxic fumes. However, according to a study by EPA, the tests to determine whether a chemical meets the characteristic tests for hazardousness have serious flaws. Because of the weaknesses in the tests, many hazardous wastes are unregulated.