Hazardous Waste Classification: Easier Said Than Done

The term "hazardous waste" sounds more unusual than it actually is. In reality, hazardous wastes come in many forms and can be generated in a variety of industrial and non-industrial settings. Even a school art class can generate hazardous waste if it has paint or solvent waste. Dry cleaners who use solvents, and gardeners who apply pesticide, might have hazardous wastes on their hands unbeknownst to them. (See What Makes a Waste Hazardous? Office of Solid Waste and Emergency Response, U.S. Environmental Protection Agency (EPA), No. EPA530-#-00-001e (October 2000).)

Despite how common hazardous wastes can be, determining whether you have a hazardous waste is far from routine. Under federal law, the first step is to determine whether the material in question is a solid waste. Much time and effort is spent determining what is a solid waste and whether the waste classifies as hazardous waste. Indeed, EPA has received more than 1,000 calls a month regarding hazardous waste classification, according to an EPA July 1990 study. Experts in the field call EPA's regulations defining solid waste "the most complex environmental regulations ever written." (Marcia E. Williams and Johathan Z. Cannon, Rethinking the Resource Conservation and Recovery Act for the 1990s, 21 Envtl. L. Rep. (Envtl. L. Inst.) 10,063, 10,064 (Feb. 1991).) EPA itself has admitted that the definition of solid waste is "difficult to understand and implement for EPA, the states, and industry" and that "permitting and enforcement are hampered by the complexity of those defini tions." (Id.)

In order to be regulated as a hazardous waste under federal or state law, a material must be both a "solid waste" and a "hazardous waste." Many states, like Arizona, Nevada and Oregon adopt the federal hazardous waste law, known as the Resource Conservation and Recovery Act (RCRA), and EPA's regulations in Parts 260 through 270 of Title 40 of the Code of Federal Regulations (CFR). Other states, like California and Washington, follow the federal scheme for the most part but adopt their own set of laws and regulations. Whether the applicable regulation is on a state or federal level, the inquiry almost always is the same: is a material a solid waste, and if so, is it a hazardous waste? A series of special exclusions and tests apply to each of these inquiries. This article provides a basic overview of the regulatory definitions and major exclusions so that, on a case by case basis, generators are able to initially determine whether their materials may fall within RCRA's sol id or hazardous waste schemes.

In order to be regulated as a hazardous waste under federal or state law, a material must be both a "solid waste" and a "hazardous waste."

Is a Material a Solid Waste?

Under federal law, a solid waste is any discarded material that is not otherwise excluded from regulation. Discarded materials are those that:

  • are abandoned (i.e., they are disposed of, burned or incinerated);
  • are recycled in certain ways (i.e., they are used in a manner constituting disposal, burned for energy recovery, reclaimed, or accumulated speculatively);
  • are considered inherently waste-like; or
  • are certain military munitions as defined by the regulations (40 CFR §261.2(a).)

Of the categories of wastes, it is the recycled materials that can be the most difficult to properly characterize. By EPA's own definition, solid wastes include certain recycled materials. EPA refers to materials that can potentially be solid and hazardous wastes when recycled as secondary materials. There are five types of secondary materials: byproducts, sludges, certain scrap metals, spent materials (like spent solvents or spent catalysts) and commercial chemical products that spill or are unused or off-specification (CCPs). (40 CFR § 261.2)

Focusing on these five materials, EPA regulates four types of recycling activities: use constituting disposal (usually placement on land), burning waste fuels, reclamation (processing a material to recover a useful product or regenerating a material for further use, as with spent catalysts) and speculative accumulation (storing a material that cannot be recycled in sufficient amounts). Depending on the type of secondary material, some materials may be recycled in some of these four methods while others cannot. Thus, the type of recycling activity and the material involved will determine, in part, whether a material is a solid waste.

Businesses frequently ask how can a secondary material held for recycling possibly qualify as a "waste" when RCRA defines a waste as a "discarded material?" Two major federal opinions have addressed this point and concluded -- somewhat at odds with EPA -- that discarded means disposed of, thrown away, or abandoned and does not include materials that persons or businesses save or reuse. (Association of Battery Recylcers Inc. (ABR), v. EPA, 203 F.3d 1047, 1051 (D.C. Cir. 2000); American Mining Congress v. EPA, 824 F.2d 1177, 1184 (D.C. Cir. 1987).)

There are two types of hazardous wastes: wastes that are listed and those that display characteristics of hazardous waste.

The ABR court disagreed with EPA's regulation of certain secondary materials in the primary mineral processing industry, stating "To say that when something is saved it is thrown away is an extraordinary distortion of the English language." (ABR at 1051.) The impact of the ABR decision on EPA's regulations is not entirely clear at this time. Meanwhile, therefore, the maze of solid waste identification and exclusions continues to persist, forcing waste generators to follow through the regulatory framework. Because states can be stricter than federal law, state laws, including California's, can regulate recycled materials as though they were hazardous waste regardless of the type of recycling involved. (See Cal. Health & Safety Code § 25143.2.)

Exclusions from Solid Waste Classification

Under Section 261.2(e) of the regulations, EPA excludes some recycled materials from solid waste classification when they are:

  • Used or reused as ingredients in an industrial process to make a product, provided the materials are not being reclaimed; or
  • Used or reused as effective substitutes for commercial products; or
  • Returned to the original process from which they are generated, without first being reclaimed or land disposed." (40 CFR § 261.2(e).)

EPA also excludes several specific materials from solid waste classification if the materials fit into the categories listed in Section 261.4(b), which covers materials like, but not limited to, domestic sewage, certain industrial wastewater and certain radioactive wastes. However, where a discarded material is not excluded by the regulations, it will be considered a solid waste, and the next question is whether it is a hazardous waste.

Hazardous Waste Determination

There are two types of hazardous wastes: wastes that are listed and those that display characteristics of hazardous waste. When a solid waste is a listed waste, EPA also regulates materials mixed with the listed waste to ensure that generators do not dilute hazardous wastes in order to avoid regulation.

"Characteristic hazardous wastes" are solid wastes that are considered hazardous if they are ignitable, corrosive, reactive or toxic.

About 400 wastes are considered hazardous and appear on one of four lists published in 40 CFR Part 261. EPA lists these wastes because they are known to be harmful to human health and the environment when not managed properly.

"Characteristic hazardous wastes" are solid wastes that are considered hazardous if they are ignitable, corrosive, reactive or toxic. Ignitable hazardous waste can catch fire under certain conditions. Corrosive hazardous wastes can corrode metal or exhibit a high or low pH. Reactive hazardous wastes are unstable and explode or produce toxic fumes, gases and vapors under certain conditions. Toxic hazardous wastes are fatal when ingested or absorbed, or can leach toxic chemicals into the soil or ground water. A generator determines if a solid waste is a characteristic hazardous waste by applying tests specified in the regulations or by simply knowing that the waste displays one or more of these characteristics.

EPA also regulates certain materials mixed with hazardous waste or derived from hazardous waste. A mixture of a listed hazardous waste and any other waste is regulated as a listed waste regardless of the percentage of the listed waste in the mixture. (40 CFR § 261.3(a)(2)(iv), (b)(2).) Similarly, a material such as residues, sludges or ashes derived from a listed hazardous waste is itself regulated as a listed hazardous waste. (Id. at §§ 261.3(c)(2), (d)(2).) The same rules do not apply when the mixtures or the "derived from" materials stem from a characteristic hazardous waste. In this latter case, the mixtures must be managed as a characteristic hazardous waste only if they exhibit a hazardous waste characteristic.

Exclusions from Hazardous Waste Classifications

As with solid wastes, hazardous wastes also are subject to a number of exclusions. Under federal law, household hazardous wastes are not hazardous wastes, nor are materials like, but not limited to, certain recycled used oils and certain used oil filters, certain agricultural wastes and processed scrap metal. And, certain exceptions to the "mixture" and "derived from" rules also are detailed in the regulations. (Id. at §§ 261.3(a)(2), (c)(2)(i), 261.33(a).) Not every state, however, including California, adopts all the federal exclusions.

In particular, for example, with limited exceptions, California presumes that used oil is a hazardous waste until it has been recycled in accordance with state law (Cal. Health & Safety Code § 25250) and has varying degrees of regulation over household waste items (22 Cal. Code of Regulations § 66261.7 (governing empty containers), Cal. Health & Safety Code § 25216.1 (governing spent household batteries), Cal. Health & Safety Code §§ 25217-24217.4 (governing recyclable latex paint). Since each state differs, the applicable state agency or regulations must be consulted to determine how different discarded materials are classified.


Determining whether a "discarded" material is a solid waste and, if hazardous, a hazardous waste can be a tedious task. With some idea of the regulatory framework, the relevant definitions and exemptions should be easier to identify.

This article originally appeared in the September 2001 issue of Environmental Protection, Vol. 12, No. 9, p. 20.

This article originally appeared in the 09/01/2001 issue of Environmental Protection.

About the Author

Susan Hollingshead is managing director of Greenfield International LLC, a brownfield and Superfund redevelopment management firm in Walnut Creek, Calif.