Definition by USEPA
Defined a waste to be hazardous if it meet one or more of the following conditions:
Exhibit characteristics of ignitability, corrosivity, reactivity, and/or toxicity
Is a nonspecific source waste (generic waste form industrial processes)
Is a specific source waste (from specific industries)
Is a specific commercial chemical product or intermediate
Is a mixture containing a listed hazardous waste
Is a substance that is not excluded from regulation under the Resource Conservation and Recovery Act, Subtitle C.