Overview of the Hazardous Waste Identification Process
EPA's regulations establish two ways of identifying solid wastes as hazardous under the
Resource Conservation and Recovery Act RCRA. A waste may be considered hazardous if it
exhibits certain hazardous properties ("characteristics") or if it is included on a specific list of
wastes EPA has determined are hazardous ("listing" a waste as hazardous) because we found
them to pose substantial present or potential hazards to human health or the environment. EPA's
regulations in the Code of Federal Regulations (40 CFR) define four hazardous waste
characteristic properties: ignitability, corrosivity, reactivity, or toxicity (see 40 CFR 261.21-
261.24). This document presents the regulations that will assist in identifying the characteristics
of hazardous waste in §§
261.31 through 261.33. Since EPA has developed a separate document
for listed wastes, only characteristic wastes will be discussed in this document.
Characteristic Hazardous Wastes
A RCRA characteristic hazardous waste is a solid waste that exhibits at least one of four
characteristics defined in 40 CFR Part 261 subpart C — ignitability (D001), corrosivity (D002),
reactivity (D003), and toxicity (D004 - D043).
• Ignitability– Ignitable wastes can create fires under certain conditions, are spontaneously
combustible, or have a flash point less than 60 °C (140 °F). Examples include waste oils
and used solvents. For more details, see 40 CFR §261.21. Test methods that may be
used to determine ignitability include the Pensky-Martens Closed-Cup Method for
Determining Ignitability (Method 1010A)(PDF)(1 pg, 19K), the Setaflash Closed-Cup
Method for Determining Ignitability (Method 1020B)(PDF) (1 pg, 17K), the Ignitability
of Solids (Method 1030) (PDF)(13 pp, 116K), Test Method for Oxidizing Solids (Method
1040)(PDF) (17 pp, 207K), and the Test Method to Determine Substances Likely to
Spontaneously Combust (Method 1050) (PDF)(20 pp, 611K).
• Corrosivity – Corrosive wastes are acids or bases (pH less than or equal to 2, or greater
than or equal to 12.5) and/or are capable of corroding metal containers, such as storage
tanks, drums, and barrels. Battery acid is an example. For more details, see 40 CFR
§261.22. The test method that may be used to determine the ability of a waste to corrode
steel is the Corrosivity Towards Steel (Method 1110A)(PDF)(6 pp, 37K). To measure
pH electrometrically, see Method 9040C (PDF)(5 pp, 25K).
• Reactivity – Reactive wastes are unstable under "normal" conditions. They can cause
explosions, undergo violent reactions, generate toxic fumes, gases, or vapors or explosive
mixtures when heated, compressed, or mixed with water. Examples include lithium-
sulfur batteries and explosives. For more details, see
40 CFR §261.23 . There are
currently no test methods available.
• Toxicity – Toxic wastes are harmful or fatal when ingested or absorbed (e.g., containing
mercury, lead, etc.). When toxic wastes are land disposed, contaminated liquid may
leach from the waste and pollute ground water. Toxicity is defined through a laboratory
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