What Is Hazardous Waste?


What Is Hazardous Waste Image

So what is hazardous waste, you may ask?

Hazardous waste is regulated by the US EPA and The Resource Conservation and Recovery Act, or RCRA. The RCRA is a set of environmental regulations that regulates hazardous waste and more. In this article, we provide an overview of the RCRA, explain what a “hazardous waste” is (according to the EPA and RCA, naturally), and offer an online hazardous waste training suggestion for you–our RCRA Introduction online training course, which is part of our larger online Environmental training library. The online course is a great and inexpensive option for those of you who don’t want to read the full article or who want to show the course to a number of workers.

This material in this article and the online course will help your company ensure you’re treating hazardous wastes properly, not running afoul of environmental regulations, and doing your share to protect the environment around us. It will also offer suggestions and samples of hazardous waste training courses.

This article is a continuation of our look at online environmental training courses. You may also want to check our earlier article on The EPA, Environmental Regulations, and Online Training and our article on What Is RCRA?

Before you begin reading, feel free to watch the short video overview of a few highlights from our Environment, Health, and Safety (EHS) online training library.

What Is RCRA?

RCRA is an acronym and it stands for the Resource Conservation and Recovery Act.

According to the EPA, “the term RCRA is often used interchangeably to refer to the law, regulations, and EPA policy and guidance.” They then break down that further:

  • Law: This is the waste management program that Congress passed. It gave the EPA the authority to develop the RCRA program.
  • Regulations: These are in Title 40 of the Code of Federal Regulations (CFR), parts 239-283. They spell out specific requirements for waste management that are legally enforceable.
  • EPA policy and guidance: These are materials created by the EPA to help clarify questions, confusions, and issues related to the implementation and enforcement of the regulations above.

What Are the Different Subtitles of RCRA?

RCRA includes 10 different subtitles, listed below:

For the purposes, of this article, we’ll focus on Subtitle D (Hazardous Wastes).

RCRA–Subtitle C, Hazardous Wastes

According to the EPA:

Hazardous waste is regulated under Subtitle C of RCRA. EPA has developed a comprehensive program to ensure that hazardous waste is managed safely from the moment it is generated to its final disposal (cradle-to-grave). Under Subtitle C, EPA may authorize states to implement key provisions of hazardous waste requirements in lieu of the federal government. If a state program does not exist, EPA directly implements the hazardous waste requirements in that state. Subtitle C regulations set criteria for hazardous waste generators, transporters, and treatment, storage and disposal facilities. This includes permitting requirements, enforcement and corrective action or cleanup.

Subtitle C focuses on hazardous wastes and includes 40 CFR parts 260-273. In particular, those regulations include:

Online Hazardous Waste Training for RCRA–Subtitle C, Hazardous Wastes

If you’re looking for RCRA hazardous waste training, we’ve got a great course for you below.

We offer an Introduction to RCRA online training course to help you get up to speed on the regulations. Here’s a short sample.

The online course covers all of the topics written about below, plus more. You can begin viewing a copy of the course in pay-per-view online video, video on USB, or enterprise learning (eLearning & LMS) whenever you want here.

Is it a Solid, Hazardous Waste?

There is a four-step process for determining if a waste is a solid, hazardous waste subject to the Title C regulations.

The four steps are:

  1. Determine if the waste is a solid waste
  2. Determine if the waste is specifically excluded from RCRA
  3. Determine if the waste is a listed hazardous waste
  4. Determine if the waste is a characteristic hazardous waste

Let’s walk through that process.

First question: Is it a solid waste?

The EPA defines solid waste as “garbage, refuse, sludge, or other discarded material (including solids, semi-solids, liquids, and contained gaseous materials).” Click to read more about the EPA definition of solid waste.

Second question: Is the waste excluded from RCRA?

The EPA can exclude a waste from RCRA because they do not consider it “solid waste” and also because they don’t consider it “hazardous.” You can read more about wastes that the EPA excludes from RCRA here. You can also check out 40 CFR section 261.4(a) for more about solid waste exclusions and 40 CFR section 261.4(b) for more about hazardous waste exclusions.

Third question: Is the waste a listed hazardous waste?

The EPA maintains four separate lists of hazardous wastes. According to the EPA, “A waste is determined to be a hazardous waste if it is specifically listed on one of four lists (the F, K, P and U lists) found in title 40 of the Code of Federal Regulations (CFR) in section 261.”

Here’s more about those lists:

F list: The F list “identifies wastes from common manufacturing and industrial processes as hazardous. Because the processes generating these wastes can occur in different sectors of industry, the F list wastes are known as wastes from non-specific sources.” The F list can be found at 40 CFR section 261.31. (Source: EPA)

K list: The K-list identifies hazardous wastes from specific sectors of industry and manufacturing and are considered source-specific wastes. To qualify as a K-listed hazardous waste, a waste must fit into one of the 13 categories on the list and the waste must match one of the detailed K list waste descriptions in 40 CFR section 261.32. (Source: EPA)

P and U lists: The P and U lists designate as hazardous waste pure and commercial grade formulations of certain unused chemicals that are being disposed. For a waste to be considered a P- or U-listed waste it must meeting the following three criteria:

  • The waste must contain one of the chemicals listed on the P or U list
  • The chemical in the waste must be unused; and
  • The chemical in the waste must be in the form of a commercial chemical product. (Source: EPA)

P list: The P list identifies acute hazardous wastes from discarded commercial chemical products and can be found at 40 CRF section 261.33.

U list: The U list identifies hazardous wastes from discarded commercial chemical products and can be found at 40 CFR section 261.33.

Fourth question: Is it a characteristic hazardous waste?

According to the EPA, “a hazardous waste characteristic is a property which, when present in a waste, indicates that the waste poses a sufficient threat to merit regulation as hazardous.”

Hazardous Waste Codes

The EPA uses hazard codes in each list to designate why a waste is listed as hazardous. The hazard codes determine the regulations that apply to the waste.

The six codes are:

  • Toxic waste (T)
  • Acute hazardous waste (H)
  • Ignitable waste (I)
  • Corrosive waste (C)
  • Reactive waste (R)
  • Toxicity characteristic waste (E)

Waste Characteristics: Ignitability, Corrosivity, Reactivity, and Toxicity

The EPA has defined four hazardous waste characteristics: ignitability, corrosivity, reactivity and toxicity. They are discussed more below.


Wastes that are hazardous due to the ignitability characteristic include liquids with flash points below 60 °C, non-liquids that cause fire through specific conditions, ignitable compressed gases and oxidizers. EPA assigned D001 as the waste code for ignitable hazardous wastes. For more about ignitability, see 40 CFR section 261.21 and the Ignitability Characteristic Background Document.

Ignitability is explained in this sample from our RCRA Introduction online training course.


Wastes that are hazardous due to the corrosivity characteristic include aqueous wastes with a pH of less than or equal to 2, a pH greater than or equal to 12.5 or based on the liquids ability to corrode steel. EPA assigned D002 as the waste code for i hazardous wastes. For more about corrosivity, see 40 CFR section 261.22 and the Corrosivity Characteristic Background Document.


Wastes that are hazardous due to the reactivity characteristic may be unstable under normal conditions, may react with water, may give off toxic gases and may be capable of detonation or explosion under normal conditions or when heated. EPA assigned D003 as the waste code for reactive hazardous wastes. To learn more about reactivity, see 40 CFR section 261.23 and the Reactivity Characteristic Background Document.


Wastes that are hazardous due to the toxicity characteristic are harmful when ingested or absorbed. Toxic wastes present a concern as they may be able to leach from waste and pollute groundwater. To learn more about toxicity and toxicity testing, see 40 CFR section 261.24.

Additional Rules to Know about Hazardous Wastes

It’s also important to know about the mixture rule, the derived-from rule, and mixed radiological wastes. Each are described in more detail below.

The Mixture Rule

The mixture rule states that a mixture made up of a non-hazardous solid waste and any amount of a listed hazardous waste is considered a listed hazardous waste.

Even if only a small amount of a listed waste is mixed with a large amount of a non-hazardous waste, the mixture is considered hazardous.

The Derived-From Rule

The derived-from rule states that any material derived from a listed hazardous waste is also a listed hazardous waste.

An example would be ash left behind after burning a listed hazardous waste.

Mixed Radiological Wastes

A mixed radiological waste, or simply mixed waste, is a radiological waste that is also a hazardous waste under RCRA.

Mixed wastes are jointly regulated by RCRA and the Atomic Energy Act.

Conclusion: Online Hazardous Waste Training

We hope the information above helped you understand what the EPA considers to be “hazardous waste” under the Resource Conservation and Recovery act.

For additional information related to environmental compliance, check these other articles:

We also hope you’ll find our RCRA Basics online course helpful.

You may also want to check out the following online Environmental training courses.

RCRA Online Courses

Spill Prevention, Control, and Countermeasures (SPCC) Online Courses

Stormwater Online Courses

Pollution Control Online Courses

And don’t forget to download the free guide below.

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Benefits of Online Safety Training

Wondering if you should make the plunge with online safety training? This guide gives 10 reasons why, each based on experiences at real companies like yours.

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