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How To Read Hazardous Materials Symbols And What They Mean

Hazardous and toxic materials pose a real threat to safety. It’s a complicated waste stream, but it's something RoadRunner has extensive experience with.

Bradford Arick | September 22, 2022


Explosions. Burns. Changes to DNA. These are all things possible with hazardous and toxic materials. It’s a complicated and dangerous waste stream, but it's something RoadRunner has extensive experience with.

There are nine pictograms OSHA established for these substances. Each one is a warning label, letting employees and waste haulers understand what they’re dealing with. Having a better understanding of these symbols can help your business’s waste stream management.

We explain what the OSHA Hazard Communication Pictograms are and the dangers posed by each.


Health Hazard

• Carcinogen

• Mutagenicity

• Reproductive toxicity

• Respiratory sensitizer

• Target organ toxicity

• Aspiration toxicity

This includes chemicals that can permanently alter a person’s DNA causing mutations, can cause cancer, are toxic to reproductive organs, and can cause issues with a person’s respiratory system.

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• Flammables

• Pyrophorics

• Self-heating

• Emits flammable gas

• Self-reactivates

• Organic peroxides

Things that fall under the flammable category include chemicals that can spontaneously combust, substances that heat up when exposed to oxygen in the air, chemicals that are powerful bleaching agents, and others that can unintentionally explode.


Exclamation Mark

• Skin, eye irritant

• Skin sensitizer

• Acute toxicity

• Narcotic effects

• Respiratory tract irritant

• Hazardous to the ozone layer

Chemicals in this area can cause an allergic reaction response if they come into contact with a person’s skin. These substances can be toxic to people in short doses and a short amount of time. Additionally, chemicals under this umbrella can have narcotic effects on a person, meaning drowsiness, confusion, nausea, euphoria, and slowed reaction times. 


Gas Cylinder

• Gases under pressure

Gasses under pressure are defined as gas that is liquefied or liquefied and refrigerated, and gas that is in a container with a pressure of 29 pounds per square inch. Nitrogen, carbon dioxide, and helium all fall under this category. These substances can be toxic, flammable, or corrosive and cause fire, asphyxiation, or chemical burns.



• Skin corrosion/burns

• Eye damage

• Corrosive to metals

Skin corrosion can be irreversible and result in the visible death of skin cells for a person. Substances that cause that reaction fall into this area. These chemicals can also cause a reaction with metal, essentially “eating away” at it.


Exploding bomb

• Explosives

• Self-reactives

• Organic peroxides

Self-reactive chemicals are unstable substances that can undergo a reaction on their own that produces large amounts of heat. This can lead to fires, detonations, or explosions. 


Flame over circle

• Oxidizers

One example of an oxidizer is a chemical that initiates or helps create combustion in another material. Common chemicals include chlorine, hydrogen peroxide, and sulfuric acid. The danger here lies in that these substances have the ability to combine with oxygen and increase the chance of an explosion.


Environment (non-mandatory)

• Aquatic toxicity

Aquatic toxicity at its basic level has to do with the effects a chemical can have on things living in a marine environment. These chemicals have a significant impact on reproductive, immune, endocrine, and nervous systems of animals and people. 


Skull and crossbones

• Acute toxicity (fatal or toxic)

These substances can quickly cause death or poisoning. Examples of chemicals in this category include ammonia, nitric acid, antifreeze, and bleach.

Our hope is that RoadRunner can help raise awareness and education about what these symbols mean. Your company can stay ahead of the game when it comes to keeping employees safe. Your business can also get a better understanding of how to properly handle and transport these chemicals when figuring out waste management plans.

RoadRunner handles a variety of waste streams, including hazardous materials, and we’re able to dispose of them safely and efficiently.

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