WHMIS – Your Guide to Hazardous Materials Labeling in the Workplace

Across a range of industries, chemicals and controlled substances are imported and exported on a daily bases. In fact, in most industrial production settings, you’d be hard-pressed to find a warehouse or facility not using these materials. The WHMIS is Canada’s “Workplace Hazardous Materials Information System,” and seeks to keep workers informed of the type of material and its associated risks in any container that enters the work space. In the U.S., the equivalent is the American Hazard Communication Standard, usually referred to as simply the HCS. Both systems fall roughly in line with the United Nations’ overarching Globally Harmonized System of Classification and Labelling of Chemicals (a mouthful that is thankfully pared down to just “GHS” in most contexts). Oddly enough, most of the information readily available, and the most-used acronym to denote such policies, is still the Canadian WHMIS. In this blog post, we’re going to go over aspects of the WHMIS in detail to help you understand how to best protect your employees.

WHMIS Basic Requirements and Goals

The main goal of any WHMIS system is to create a uniformed way of communicating hazardous materials and their risks. The original WHMIS requires that this be done in the following three ways by any employers who have hazardous chemicals or controlled substances imported into their business:

  • Visual labeling on the containers themselves must indicate the class of material and its associated safety risks.
  • Managers must possess data sheets for each shipment of materials which detail all inventory being received and their associated safety risks.
  • Training to teach employees about the materials they will be working with is required in addition to any labeling and data sheets.

Container Labeling

WHMIS and equivalent systems will break down various materials into their own classes. These classes are then associated with images, which are used in conjunction with text on barrels and other containers. In WHMIS, the classes are:

  • WHMIS symbols from Wikipedia
    WHMIS symbols from Wikipedia

    Class A: Compressed gases; any pressurized material must be labeled as such. Class A materials are at risk of puncturing if not handled with care.

  • Class B: Flammable and combustible materials; chemicals and materials at high risk of catching fire must be labeled as Class B. This is one of the most common classes to see in chemical and production plants.
  • Class C: Oxidizing materials; while oxidizing materials may not be considered combustible on their own, they too provide a fire hazard. Oxidizing materials can decompose quickly to yield oxygen, the main component in any fire. Because of this, oxidizing materials can prevent a fire risk even in areas where oxygen would usually be too low to support flames.
  • Class D-1: Immediate toxic effects; any substance which can produce burns, unconsciousness, or other serious health effects within seconds, minutes, or hours are placed under the D-1 banner. These materials often also cause ongoing, long term health defects even after their initial symptoms have subsided.
  • Class D-2: Materials with other toxic effects; the effects of D-2 substances may be less severe or last for a shorter time than their D-1 counterparts. That said, D-2 materials can still also possess long term carcinogenic (cancer-causing) effects.
  • Class D-3: Biohazard & Infectious Materials; these items are usually comprised of bacteria or organisms that can causes illness and infection in humans and animals. Many of these materials come from medical waste.
  • Class E: Corrosive Materials; any substance that can eat through human tissue (skin, eyes, other membranes) and cause chemical burns falls under class E. Corrosive materials are also fairly common across a variety of sectors.
  • Class F: Dangerously Radioactive Materials; radioactive materials, namely those unstable and which can quickly change temperature, moisture content, and/or composition fall under this class.


It is important that you know that WHMIS standards generally only apply to materials produced for wholesale at the industry level. This means that if you use products already sold to the general public with their own labeling, you don’t need to label them again to comply with WHMIS standards. That said, if they are dangerous to employees in any way, as much should be made known via your training (or it may be a good idea to just make new and more prominent labels anyways). These labels can be printed using an industrial label maker. An example of this would be an LabelTac industrial label maker.

Data Sheets

While the exact criteria varies between systems, most will require the same general information. First of all, the burden of the data sheets (DS) falls to the provider of the material, not to the manager or business receiving it. That said, managers should refuse any shipments with missing or incomplete data sheets. All hazardous ingredients should be listed in the DS so that all aspects are easily identified upon receipt. Next, the process through which the materials were prepared, and the parties or departments responsible for preparation should be denoted. Contact information for the supplier should also be provided, along with their name for that product and its intended uses. Physical data and description of the product should be included next, followed by any immediate risks (those from the “Classes” mentioned before). Reactivity and toxicological properties should be clearly stated on each DS. Any associated steps for preventing problems or injuries with the product, along with any first aid measures, should be included as well.


Training is generally restricted to the communication of the above information, with the intent of every employee becoming sufficiently knowledgeable about the materials he or she is working with. Using training DVD’s (like this hazard communication training DVD) Managers should focus on preventative and first aid procedures as they are likely to be the most relevant in your overall safety programs.

Additional Resources