What is a HAZWOPER Hazardous Substance?

Posted on 5/24/2021 by Joel Gregier, CDGP

The Hazardous Waste Operations and Emergency Response standard, also known as HAZWOPER, is an OSHA health and safety Standard relating to hazardous substance cleanup, treatment, and emergency response. 

The key word here is “hazardous substance.”  Thus, if you have a cleanup or emergency response related to a hazardous substance release, you become subject to HAZWOPER.

Hazardous This, Hazardous That 

There are a lot of “hazardous” terms when dealing with different sets of regulations. 

The Department of Transportation regulates shipments of “hazardous materials," for instance.  The Environmental Protection Agency regulates the management and disposal of “hazardous wastes.” The list goes on.

To define “hazardous substance” under the HAZWOPER Standard, OSHA simply adopts other agencies’ “hazardous” things.  In so many words, OSHA says “Yeah, what they said.

The 4 Hazardous "Things" Subject to HAZWOPER

OSHA defines a “hazardous substance” as any substance that is “designated or listed under paragraphs (A) through (D) of this definition, [where] exposure to which results or may result in adverse effects on the health or safety of employees”  [29 CFR 1910.120(a)(3)].

When you look at the paragraphs (A) through (D), you’ll notice OSHA simply adopts four categories of “hazardous” things from other agencies’ definitions. 

They include the following:


A. Hazardous Substances as defined under CERCLA. This is a list that EPA curates to include substances that can damage the environment when released. CERCLA hazardous substances include chemicals such as acetamide, aldrin, benzene, chlorine, and many others.  A full list of hazardous substances defined under CERCLA can be found at 40 CFR 302.4

B. “Biological agents” and “other disease-causing agents,” exposure to which can lead to death, disease, behavioral abnormalities, cancer, genetic mutation, physiological malfunctions, or physical deformations. This is the only letter that was not directly adopted from another agency, but you can almost think of these as “things the CDC would care about.”

C. “Hazardous materials” as defined by the US DOT. Anything covered by DOT’s Hazardous Materials Regulations (HMR) is subject to HAZWOPER if a cleanup or emergency response needed to take place. This could include materials such as acetone, gasoline, sulfuric acid, turpentine, etc.

To get a feel for what could be considered hazmat under DOT, you can check out the DOT’s Hazardous Materials Table found at 49 CFR 172.101. In the Hazmat Shipper Starter Guide, Lion details DOT's hazard classes and divisions on page 2. 

D. “Hazardous waste” as defined by the EPA. Wastes that could endanger humans or the environment have specific rules in terms of managing and disposing of those hazardous wastes. This could include spent xylene, contaminate wastewaters, used acid baths, or unused chemicals being disposed of. EPA’s criteria for hazardous wastes are found at 40 CFR 261.3.

What is a HAZWOPER Hazardous Substance?

Do Other Regulations Trigger HAZWOPER Training?

Because the HAZWOPER definition of hazardous substance references other regulations, it may confuse some employees about whether OSHA requires them to complete HAZWOPER training.  For instance, if I am a hazmat employee that prepares hazmat shipment under DOT jurisdiction, do I now also need HAZWOPER training?

In short, being subject to the DOT hazardous materials or EPA hazardous waste rules listed above does not immediately pull you into HAZWOPER. HAZWOPER training is required if you deal with cleanup, treatment, or emergency response of these substances. 

For more information of what triggers HAZWOPER training, check out the blog Who Really Needs HAZWOPER Training?

More HAZWOPER Resources 

For a visual explainer of who needs HAZWOPER training and how many training hours are required, see our HAZWOPER explainer graphics linked below:

HAZWOPER Emergency Responder Training
HAZWOPER Site Cleanup Training 

Online HAZWOPER Training: Convenient and Effective  

Find HAZWOPER training required for emergency responder and contaminated site clean-up workers at

Each HAZWOPER course available at can be completed 100% online and is designed to help satisfy training mandates for employees subject to OSHA's HAZWOPER Standard at 29 CFR 1910.120.

Tags: hazardous substances, HAZWOPER, HAZWOPER training

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