Which Hazardous Waste Symbol Should a Facility Use?

Hazardous waste symbols and pictograms are the fastest, most efficient and reliable way to communicate warnings. People comprehend the meaning of symbols much quicker than they do text. There are many types of hazard warning symbols. You may be wondering which ones provide a warning about hazardous waste. First, we need to understand the definition of hazardous waste.

The Environmental Protection Agency (EPA) defines Hazardous Waste as waste that is dangerous or potentially harmful to our health or the environment. Hazardous waste can be liquid, solid, gas, or sludge. It can be discarded commercial products, like cleaning fluids or pesticides, or the by-products of manufacturing processes. Each of these materials must be clearly identified with the appropriate hazardous waste symbol.

What Makes a Material Hazardous and When Is a Hazardous Waste Symbol Required? 

The EPA has a number of standards that make identifying hazardous waste easy, without the need to perform laboratory testing. However, for the purposes of labeling, understanding the EPA's four basic characteristics of hazardous waste is important. By knowing these you'll know which hazardous waste symbol should be included on the label. The following are the definitions provided by the EPA (note that the EPA does not regulate radioactive waste):

1. 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.
2. Corrosivity - Corrosive wastes are acids or bases (pH less than or equal to 2, or greater than or equal to 12.5) that are capable of corroding metal containers, such as storage tanks, drums, and barrels. Battery acid is an example of a corrosive hazardous waste.
3. Reactivity - Reactive wastes are unstable under "normal" conditions. They can cause explosions, toxic fumes, gases, or vapors when heated, compressed, or mixed with water. Examples include lithium-sulfur batteries and explosives.
4. Toxicity - Toxic wastes are harmful or fatal when ingested or absorbed. Wastes that contain mercury or lead are toxic wastes. Toxicity is defined through a laboratory procedure called the Toxicity Characteristic Leaching Procedure (TCLP). The TCLP helps identify wastes likely to leach concentrations of contaminants that may be harmful to human health or the environment.

The EPA has made identifying many hazardous wastes easy by classifying wastes into four general categories. This eliminates the need for every workplace to individually test their wastes. The four categories of EPA hazardous waste are:

1. Listed Wastes: These are wastes the EPA has determined are hazardous based on EPA testing.  The wastes are identified based on the source of the waste. The lists include the F-list (wastes from common manufacturing and industrial processes), K-list (wastes from specific industries), and P- and U-lists (wastes from commercial chemical products).
2. Characteristic Wastes: These are wastes that do not meet any of the listings above but they have one of the four characteristics of hazardous waste regulated by the EPA: ignitability, corrosivity, reactivity, or toxicity.
3. Universal Wastes: These are specific objects that, when disposed of as waste, are hazardous or have hazardous components.  These include batteries, pesticides, mercury-containing equipment such as thermostats, and lighting (lamps) such as fluorescent bulbs.
4. Mixed Wastes: This is waste that contains both radioactive and hazardous waste components.

In addition to these, there are hazardous radioactive wastes and hazardous biological wastes.  All of these need to be labeled correctly, with the correct hazardous waste symbol.

Hazardous Waste Symbol Basics and Common Uses

Once the type of hazardous waste has been identified, and its characteristics are known, the correct labeling with the appropriate hazardous waste symbols can be applied. Many hazardous waste symbols may also be used on various other types of labels. Use of these symbols identifies a hazard, but it may not be specific to hazardous waste.

The EPA regulates hazardous waste in the U.S. and requires labeling of hazardous waste containers. In many cases, except for bio-waste, there are no symbols required on EPA labels. However, symbols communicate information faster and more accurately than text alone. It is common to use symbols on hazardous waste labels and signs to increase effectiveness, including when a toxic waste symbol is needed to identify highly dangerous materials.

The Department of Transportation (DOT) regulates the transportation of hazardous materials, including hazardous waste. DOT requires placards or labels on vehicles and containers holding hazardous materials during transport. The required placards and symbols are shown in 49 CFR 172, subpart E.

The OSHA Hazard Communication Standard (HCS) requires labeling of hazardous chemicals in the workplace using GHS labels. Since hazardous waste is regulated by the EPA, GHS labeling does not technically apply. However, because they clearly communicate hazard information, GHS symbols—or symbols similar to them—are commonly used on hazardous waste containers, including those marked with a toxic waste symbol.

For clear communication, using the appropriate GHS symbol whenever possible is recommended to identify the hazards of waste.

The International Standards Organization (ISO) also specifies hazard symbols. When an ISO symbol matches those used in North America, it is commonly accepted for hazardous waste labeling.

Hazardous Waste Symbol for Ignitable Materials

GHS / DOT / WHMIS / ISO Flammable	GHS / DOT / WHMIS / ISO Oxidizers Can burn without air.

Both of the above symbols identify flammable wastes and both are symbols specified by OSHA's Hazard Communication Standard (HCS) for GHS labels. On hazardous waste labels and signs they are often combined with the no smoking symbol. Multiple symbols may be included on a label to indicate multiple hazards, as well as prohibited activities.

Hazardous Waste Symbol for Corrosive Waste

GHS / DOT / WHMIS / ISO  Corrosive	Corrosive  (Not Recommended)

There are two symbols commonly used to identify corrosive wastes. The symbol on the left is used for GHS and WHMIS labels, and it commonly appears on hazardous waste labels identifying corrosives. This is the internationally recognized standard symbol for corrosives and is the preferred symbol. The other symbol may be seen on hazardous waste containers, or marking locations where there corrosive hazardous waste is stored. While you may encounter the second symbol, it has become outdated and should no longer be used.

Hazardous Waste Symbol for Reactive Waste

GHS  Explosive	WHMIS  dangerously  reactive material

These are materials that are violently reactive or explosive under normal conditions. The recommended GHS symbol is shown on the upper left. "WHMIS" is the acronym for the Workplace Hazardous Materials Information System used in Canada.

Hazardous Waste Symbols for Toxic Waste

GHS / DOT / WHMIS / ISO  Toxic and life threatening even in small amounts. Inhalation hazard.	GHS  Hazardous to aquatic life and the environment.	GHS  A serious health hazard. Examples of hazards include: carcinogens, mutagenicity, and reproductive toxicity.	GHS  This symbol is commonly used to indicate caution in general. Under GHS it is a general warning covering hazards such as irritation, acute toxicity, narcotic effects, or dermal or inhalation sensitizers.
WHMIS  Toxic, Poisonous or Infectious

As shown above, OSHA GHS labels have a number of different symbols that indicate a material is toxic. The GHS symbol that should be used on a hazardous waste label depends on the toxicity of the substance being labeled.

For Canada there is a single WHMIS symbol that applies to all levels of toxicity.

The ISO symbol shown above is sometimes seen in the U.S. It identifies a poisonous gas (inhalation hazard).

Other Hazardous Waste Symbols for Specialized Hazards

EPA / DOT / WHMIS / ISO  Biohazard	ISO 21482  Radiation Hazard Symbol	WHMIS/GHS / DOT /  Compressed Gas

Two other types of hazardous wastes that are identified by symbols are biohazards (regulated by OSHA and the EPA) and radioactive wastes (regulated by the NRC). The third hazard shown above is compressed gas. Compressed gas falls outside the EPA definition of hazardous waste; compressed gas is hazardous and should be labeled so that people are aware of the hazard.

How the NFPA Diamond Supports Hazardous Waste Symbol Identification

The NFPA Diamond is specified under NFPA 704 - "Standard System for the Identification of the Hazards of Materials for Emergency Response." While the hazardous waste symbols we've discussed so far are used to inform workers and the general public about the hazardous properties of wastes, the NFPA diamond is used specifically for providing information to emergency responders.

Emergency responders, such as fire fighters, need to know that hazardous materials are present. They also need to know the type of hazard, and the level of danger each type of hazard presents. This information is provided by the NFPA diamond.

The NFPA diamond has four sections, each having a different color. The colors identify the type of hazard:

• Red - flammability hazard
• Yellow - Instability hazard
• White - Special hazard
• Blue - Health hazard

Numbers from 0 to 4 identify the hazard level, with 0 being the lowest and 4 being the highest hazard level. The white section will have either an abbreviation or word that identifies any specific hazard presented by the substance.

Subtitle C of The EPA's Resource Conservation Recovery Act creates a cradle-to-grave management system for hazardous waste. The color, format, text, and symbols on a label are crucial to meet your workplace requirements. You can achieve compliance and get custom designed labels in appropriate ANSI colors with DuraLabel custom hazardous waste labels by DuraLabel. Manage hazardous waste properly with help from our free guide.

DuraLabel Hazardous Waste Symbol Resources

Hazardous waste labeling is more than a compliance step. It is a practical way to communicate risk quickly and consistently—especially when the correct hazardous waste symbol is used to identify the hazards present. Clear labels help employees recognize dangerous materials, support proper storage and handling, and reduce confusion during inspections or emergency response.

For facilities that generate, store, or transport hazardous waste, dependable labeling tools matter. An industrial sign and label system makes it easier to produce durable labels that stay legible through washdowns, chemical exposure, and daily handling. When paired with purpose-built software like LabelForge^® PRO and tough-tested supplies, teams can create consistent hazardous waste labels with the right symbols, text, and color formats for the application.

If a labeling program is being built or updated, DuraLabel’s free HazCom Labeling Quick Start Guide is a practical place to start. It helps teams understand common symbol use while offering tips for choosing materials that match the environment.

Have questions about hazardous waste labels, symbol selection, or printing supplies? Call 1-888-789-7964 to connect with a DuraLabel safety and compliance specialist.

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