Which criterion does the EPA use to classify hazardous waste?

• A. Toxicity Only
• B. Ignitability, Corrosivity, Reactivity and Toxicity
• C. Persistence
• D. Color and Odor

Answer: (B)

Hazardous waste is identified by four characteristics that indicate a real threat to health or the environment: ignitability, corrosivity, reactivity, and toxicity. Wastes that ignite easily have a flash point below 60°C, making them fire hazards. Corrosive wastes are either very acidic or very alkaline, typically with pH around ≤2 or ≥12.5. Reactive wastes can undergo violent reactions, release toxic gases, or otherwise become dangerous when disturbed. Toxic wastes are those that fail the Toxicity Characteristic Leaching Procedure (TCLP), meaning they can leach hazardous constituents into groundwater above regulatory levels. This combined framework is why the correct choice lists all four criteria. Color and odor, or persistence alone, aren’t used as the basis for classifying hazardous waste under this EPA system.