Hazardous material classification systems exist to keep workers and neighbors safe when these materials are stored, transported, and ultimately treated or disposed of. Different definitions and classes of hazardous materials (often shortened to “HAZMAT”) have been laid forth by various authorities in the United States depending on their primary concern. Understanding these classifications is imperative to preventing spills, injuries, or costly fines.

HAZMAT Classifications in the Resource Conservation and Recovery Act

The Resource Conservation and Recovery Act (RCRA) was established in 1976 and put under the responsibility of the Environmental Protection Agency (EPA). The RCRA classifies hazardous materials by their characteristics (characteristic wastes) and how they are produced (listed wastes).

Characteristics of Hazardous Materials

40 CFR defines four characteristics of hazardous materials or hazardous wastes:

  1. Ignitability
  2. Corrosivity
  3. Reactivity
  4. Toxicity

If a pure or mixed material displays any of these characteristics as they are defined in the Act, it is considered to be hazardous.

Listed Wastes

Hazardous materials are also classified according to the way they are used or produced. Once a hazardous material is no longer needed, it is considered to be a hazardous waste:

  • F-list wastes are hazardous materials produced in the course of industry and manufacturing.
  • K-list wastes are hazardous products with a specific designated purpose, such as pesticides.
  • P-list wastes are acutely hazardous substances. Most P-list wastes are discarded commercial chemicals.
  • U-list wastes are hazardous substances that are usually less toxic than P-list wastes. Most of the substances in this category are discarded commercial chemicals.

Other RCRA Hazardous Material Classifications

Universal Waste

In addition to substances that are inherently hazardous, the RCRA also defines “universal wastes,” which are commonly used household items that contain hazardous substances and can become dangerous when placed under pressure in garbage disposal trucks or buried in landfills.

The five types of universal wastes are:

  1. Aerosol cans
  2. Bulbs and lamps
  3. Batteries
  4. Mercury-containing goods
  5. Unused pesticides

Used Oil

Used oil is given a category of its own because it’s not flammable enough to be classified as a flammable liquid or toxic enough to be classed as a hazardous material, but used motor oil often contains heavy metals and polycyclic aromatic hydrocarbons (PAHs) that would be dangerous if released into the environment. For this reason, used oil and oily rags should be reused and recycled through a used oil program rather than being thrown in the trash.

Contaminated Media

Soil and water that have become contaminated with hazardous substances may be considered hazardous and will need to be handled, transported, and disposed of as such. Many hazardous waste management providers offer clean-up and decontamination services to bring businesses back into compliance with the Resource Conservation and Recovery Act and the Clean Water Act in the event of a spill.

Radioactive Substances and The Nuclear Regulatory Commission

The Department of Energy and the Nuclear Regulatory Commission have a joint responsibility to regulate radioactive materials in the United States. Needless to say, nuclear and radioactive materials are classified as HAZMAT because they present a hazard to human and environmental health if not handled correctly.

Department of Transportation (DOT) Hazardous Material Classifications

The United States Department of Transportation has nine different categories of hazardous substances that are relevant for the transportation of HAZMAT substances on highways and public roads. These categories are known as the DOT hazard classes. Each hazard class includes detailed information and substance examples, available from the Federal Motor Carrier Safety Administration website:

  • Class 1: Explosives
    • 1.1: Explosives with a mass explosion hazard
    • 1.2: Explosives with a projection hazard but not a mass explosion hazard
    • 1.3: Explosives with a fire hazard and a minor blast hazard or projection hazard (or both) but not a mass explosion hazard
    • 1.4: Explosives with no significant blast hazard
  • Class 2: Gases
  • Class 3: Flammable liquids
  • Class 4: Flammable solids
  • Class 5: Oxidizing substances and organic peroxides
  • Class 6: Toxic materials and infectious substances
  • Class 7: Radioactive materials
  • Class 8: Corrosive materials
  • Class 9: Miscellaneous

Are Electronic Goods Considered Hazardous Materials?

While they’re in use, electronic consumer goods such as computers, mobile devices, televisions, and electro-domestic appliances are not considered hazardous materials. The exception to this rule is any appliance that contains cathode ray tubes (CRTs) because CRTs contain lead in the funnel glass. Once electronic goods are no longer needed, they should be resold, refurbished, recycled, or taken to an e-waste drop-off point.

Which Classifications Are Relevant to You?

If you generate hazardous waste in the course of your work or business activities, one or several hazardous material classification systems might apply to you:


If you work with RCRA-regulated hazardous materials, you’ll need to apply for an EPA hazardous waste generator ID number and follow all of the relevant regulations when storing hazardous waste.

Likewise, if you work with radioactive materials or generate wastewater, you’ll need to comply with the Atomic Energy Act and the Clean Water Act, and the rules set forth by your state and local regulatory authorities.


If you transport hazardous materials on public roads and highways, you’ll need to use the right hazardous waste drums for each material and label each drum according to the DOT hazardous materials table.

Keep in mind that you have a cradle-to-grave responsibility for your hazardous waste, so it’s worth making sure your hazardous waste management company has an excellent reputation for secure DOT-compliant transportation.

State and Local Authorities

In addition to federal regulations, you have a responsibility to follow state and municipal regulations regarding hazardous materials, their transport, and disposal.

Many states have their own hazardous material classification that defines several non-RCRA materials as “hazardous” at a state level, including things like state-regulated medical waste.

In cases of special waste, you might need to contract with a specialty waste provider that understands the challenges of your waste type. For instance, cannabis businesses will typically work with a cannabis waste disposal provider that can handle conventional cannabis waste as well as any hazardous waste generated by the business.

Know Your Materials and the Regulations That Apply

As you will have seen, there are many different kinds of hazardous materials that are regulated by federal and state authorities due to their potential to cause harm. These materials must be handled, stored, labeled, transported, disposed of, treated, or recycled according to regulations to avoid being landed with a fine.

To ensure that you’re in full compliance, check the national, state, and local laws and make sure you have data safety sheets for every HAZMAT and chemical you use. If you need any additional advice, a reputable hazardous waste management company in your area will be happy to help.