Hazcom symbols

Last updated on January 21, 2021

Whether you are working in a laboratory, buying paint thinner at the hardware store, or driving behind a gasoline tanker truck on the road, you regularly see hazard communication (HAZCOM) symbols. These symbols can assist in keeping you safe as well as identify the hazards at the site that may need special waste disposal.

The US Department of Transportation (DOT) determines the markings for hazardous materials in transit. These labels and placards are color-coded, with pictograms and the DOT hazard class (number in the bottom corner of the diamond).

HAZCOM Standard Safety Labels

The Global Harmonized System of Classification and Labeling of Chemicals (GHS) through OSHA defines the pictograms used on Safety Data Sheets (SDS). The United Nations adopted GHS in 2003 to improve compliance on an international level.  Very similar to the pictograms on DOT containers, these are black and white images with a red border.

The National Fire Protection Association (NFPA) diamond is a “Standard System for the Identification of the Hazards of Materials for Emergency Response.” Each color represents a different hazard, and as the numbers climb, the higher the hazard.
NFPA diamond

  • Red: Flammable
  • Blue: Health
  • Yellow: Instability
  • White: Specific (e.g., oxidizer, water-reactive, corrosivity)

Below are some hazardous categories and related symbols to look out for.

Flammable: capable of being easily ignited and of burning quickly. Materials with these symbols should be kept away from flames/heat sources and would likely be hazardous waste when it comes time for disposal.

Toxic: containing or being poisonous material, especially when capable of causing death or serious debilitation. Toxic materials can cause a variety of health hazards (cancer, organ failure, death) depending on the material, dosage, and exposure.
toxic skull

Corrosive: tending or having the power to corrode (eat away by degrees). Be sure to avoid direct skin contact with corrosive material. Make sure the container it is stored in is appropriate. You don’t want to see acids kept in a metal drum!

Reactive: readily responsive to a stimulus, including, but not limited to, water, friction, or heat.

Oxidizer: an oxidizer, or oxidizing agent, will combine a chemical/material with a source of oxygen. This can cause or contribute to the initial or enhanced combustion of original material. For example, something that was non-hazardous before could become highly flammable after exposure to an oxidizer.

Gas: can be classified as toxic, flammable, oxidizing, corrosive, or inert. Lab equipment often operates with nitrogen and oxygen lines. Meter-dose inhalers also contain gas as the means of delivering medication.


Hazard communication is all around you if you look. Contact us to learn more about our hazardous waste solutions.

Chandra Lippitt has a Bachelor of Science degree in Chemistry from Colorado School of Mines. She is certified in RCRA and DOT as well as 40 Hour HAZWOPER certified. Chandra has been in the hazardous waste industry since 2008 and has managed industrial, healthcare, retail, and governmental clients, both large and small.

published in Hazardous WasteTagged