What are WHMIS symbols?

The Workplace Hazardous Materials Information System (WHMIS) updated the term symbols to pictograms in 2015 to align with the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). They’re visual tools used to quickly convey the hazards associated with hazardous products. WHMIS pictograms use symbols to show health risks associated with a hazardous product: for example, if it’s toxic or corrosive.

What are WHMIS pictograms?

Most WHMIS pictograms feature a distinctive red, diamond-shaped border around a symbol. The symbol inside the red border represents the potential hazard. It’s important to understand that the entire pictogram, including the red border and the symbol, signifies the hazard. Each pictogram corresponds to specific hazard classes and categories, ensuring risks are communicated consistently.

To help you identify the different types of WHMIS symbols and pictograms, refer to the graphic below, which displays the different hazard pictograms.

1. The bold text indicates the name of the pictogram;
2. The words in brackets describe the hazard it represents.

How many WHMIS symbols pictograms are there?

While the exact number of WHMIS symbols and pictograms can sometimes vary slightly based on specific subcategories or updates to the GHS system, which WHMIS aligns with, there are generally considered to be ten core WHMIS pictograms. 

These ten pictograms cover the most common and significant hazard classes. It’s crucial to understand each of these symbols as they provide a quick visual cue to the type of hazard a product presents.   

These ten core pictograms are:

1. Explosive: A bomb-like symbol indicating a risk of explosion.   
2. Flame: A flame symbol representing flammability hazards.   
3. Oxidizing: A flame over a circle, indicating that the chemical can cause or intensify a fire.   
4. Gas Cylinder: A gas cylinder symbol for compressed gases.   
5. Corrosive: A symbol showing a chemical corroding metal and a hand, representing corrosive damage.
6. Acute Toxicity: A skull and crossbones symbol for highly toxic substances.   
7. Health Hazard: An exclamation mark indicating various health hazards, such as skin irritation or respiratory sensitization.   
8. Health Hazard: A silhouette with a star or other symbol in the chest area, representing more serious long-term health hazards like carcinogenicity or respiratory sensitization.
9. Biohazardous Infectious Material: A symbol with three interlocking circles, indicating biological hazards.   
10. Environmental Hazard: A dead tree and a dead fish, represent hazards to the aquatic environment.

It’s important to remember that these pictograms are standardized and easily recognizable. Their consistent design helps ensure that hazard information is communicated clearly and effectively across different workplaces and even internationally.

What are the WHMIS hazard groups?

WHMIS deals with two main groups of hazards: physical hazards and health hazards.  Understanding these categories is crucial for safe handling and storage of chemicals in the workplace. Each group includes various hazard classes that have specific hazardous properties. Let’s explore them in more detail.

Physical hazards

Physical hazards relate to the physical or chemical properties of a product that can pose a danger. These hazards can cause immediate harm, such as fires, explosions, or damage to property. These hazards are about what the product does when it’s mishandled or comes into contact with certain conditions. 

Health hazards

Health hazards, on the other hand, are concerned with the potential of a product to cause health effects. These effects can be immediate or long-term. It’s about what the product does to your body if you are exposed. 

Understanding the difference between physical and health hazards, and the specific classes within each group, is fundamental to interpreting WHMIS pictograms and ensuring workplace safety.

What are the WHMIS hazard classes?

WHMIS hazard classes group together hazardous products that share similar properties. These classes are widely used internationally by countries that have adopted the Globally Harmonized System of Classification and Labelling of Chemicals System (GHS). However, some hazard classes are unique to WHMIS.

Think of hazard classes as a way to organize hazardous materials into groups with similar dangers. This makes it easier to understand the risks associated with a product and implement appropriate safety measures. For example, all flammable liquids, regardless of their specific chemical composition, would fall under the « Flammable Liquids » hazard class.

Why are WHMIS symbols and hazard classes important?

• Quick Identification of Hazards: Knowing the hazard class of a product allows workers to quickly understand the potential dangers involved.
• Appropriate Handling and Storage: Different hazard classes require different handling and storage procedures. Understanding these classifications ensures that hazardous materials are handled safely.
• Consistent Communication: The use of standardized hazard classes ensures consistent communication of hazard information across different workplaces and even internationally.
• Regulatory Compliance: Adhering to WHMIS hazard class regulations is essential for workplace safety and legal compliance.

In the following sections, we’ll delve into the specific physical and health hazard classes defined by WHMIS symbols, providing detailed explanations and examples of each.  This will give you a comprehensive understanding of how hazardous materials are classified and how to interpret WHMIS pictograms and labels effectively.

Physical hazard classes

Common examples of physical hazard classes include:

Physical Hazard Class	Class Description
Flammable gases Aerosols Flammable liquids Flammable solids	Products that ignite or explode easily. The main hazards are fire or explosion. The aerosols class also includes a category for non-flammable aerosols that may be a hazard if exposed to heat or flame.
Oxidizing liquids, solids, and gasses	Products that are classified as oxidizers and can cause or intensify a fire or explosion.
Gases under pressure	Products in this class include compressed, liquefied, dissolved, and refrigerated gases. The main hazard is the high pressures contained in the cylinder or container. Refrigerated liquefied gases can be cold enough to cause severe cryogenic burns. The product container may also explode if exposed to heat.
Self-reactive mixtures and substances	These products can cause a fire and react on their own. They can also cause an explosion if exposed to heat or flames.
Pyrophoric liquids and solids	These products catch fire spontaneously if exposed to air.
Self-heating substances and mixtures	These are products that may catch fire if exposed to air. They differ from pyrophoric liquids and solids in that they ignite after a longer exposure period or when found in large quantities.
Substances and mixtures that emit flammable gases when in contact with water	These products react with water and release flammable gases that may ignite quickly or spontaneously.
Organic peroxides	Products that, if exposed to heat, may cause a fire or explosion.
Corrosive to metals	These products can chemically damage, corrode, or destroy metals.
Combustible dust	These are products that are finely ground or divided into solid particles. These particles may catch fire or explode if dispersed into the air.
Simple asphyxiants	These products are gases that can displace oxygen in the air and can cause rapid suffocation.
Physical hazards not otherwise classified	This class covers physical hazards not classified under other physical hazard classes. The hazard must result from a chemical reaction that can cause severe injury or death at the time of the reaction to be included here. If a product is classified under this class, the hazard statement on the label and SDS provides a detailed description of the hazard.
Chemicals under pressure	This class includes liquids or solids packaged in a container other than an aerosol dispenser which are pressurized with a gas at a pressure of 200 kPa or more at 20 °C and excludes any gas under pressure

Health hazard classes

Examples of health hazard classes include:

Health Hazard Class	Hazardous Product Description
Acute toxicity	These are products that can be fatal, toxic, or harmful if they contact skin, are inhaled, or are swallowed. Acute toxicity refers to effects that occur after exposure to a single dose or several doses within 24 hours, or inhalation exposure of four hours. Acute toxicity can result from exposure to the product itself or from exposure to a product that releases gaseous substances that can cause acute toxicity upon contact with water.
Skin corrosion or irritation	These are products that cause severe skin burns, such as corrosion, ulcers, bleeding, and scabbing, or products that cause skin irritation.
Serious eye damage or eye irritation	These products can cause serious damage to the eyes, including tissue damage or vision decay, or cause eye irritation.
Respiratory or skin sensitization	Respiratory sensitizers are products that can cause breathing difficulties or induce asthma or allergy symptoms if inhaled. Skin sensitizers are products that can cause an allergic response after skin contact.
Germ cell mutagenicity	These products may cause or are suspected of causing hereditary gene mutations or permanent changes to cells that can be transmissible to future generations.
Carcinogenicity	Products in this hazard class may cause cancer or may increase the possibility of cancer.
Reproductive toxicity	These products can damage fertility and sexual function, harm unborn children, fetuses, and embryos, or cause adverse effects through lactation.
Specific target organ toxicity – single exposure	Products in this class can harm organs like the liver, kidneys, and blood after one exposure. It also includes products that may cause respiratory irritation and those that cause drowsiness or dizziness.
Specific target organ toxicity – repeated exposure	These products cause or may cause damage to organs after prolonged or repeated exposure.
Aspiration hazard	Aspiration hazards occur when liquids or solids are inhaled into the trachea or lungs through the mouth or nose. Products in this class can result in severe health problems, including chemical pneumonia, lung damage, and even death.
Biohazardous infectious materials	These products are microorganisms, nucleic acids, or proteins that cause or are suspected of causing infections, with or without toxicity.
Health hazards not otherwise classified	This class covers hazards that are not included in any other health hazard class. These hazards occur following acute or repeated exposure and have adverse health effects that can be fatal. If a product is classified in this class, the hazard statement describes the nature of the hazard.

What are the WHMIS symbols and hazard categories?

Every WHMIS hazard class has at least one hazard category assigned to it. Each hazard category is identified by an alphabetical letter: A, B, and so on. Some hazard classes have subcategories identified by a combination of a number and a letter, for example, 1A, 1B, and so on.

Generally, a lower number or earlier letter in the alphabet indicates a higher degree of hazard. So category 1A is more hazardous than 1B, while 1B is more hazardous than 2A, and so on. While some hazard classes have only one category, others can have five categories or more. Understanding the hazard categories helps users to identify hazardous materials at a glance.

Exceptions and special cases for some WHMIS symbols

Suppliers must assess products covered by the Hazardous Products Act against specific criteria as mandated by the Hazardous Products Regulations. A product is considered hazardous if it meets any of the criteria for a hazard class. All hazardous products should be labelled according to the regulations and accompanied by a corresponding safety data sheet (SDS). 

The SDS provides the hazard class and category in Section 2 (Hazard Identification). Each hazard class or category must use specific pictograms and label elements to indicate the hazard present and appropriate precautions to take. Use the information provided by the label and SDS to be informed and know how to safely use, handle, store, and dispose of the hazardous product. 

While the letter/number system is common, there are some exceptions:

• Gases Under Pressure: Instead of the typical A, B, C system, gases under pressure are categorized based on their physical state when packaged: For example, compressed gas or liquefied gas. These categories describe the packaging method, not the specific level of danger the gas poses. You’ll need additional information (like the gas’s flammability or toxicity) to understand the full hazard.
• Reproductive Toxicity: This class has a subcategory called « Effects on or via Lactation, » This subcategory doesn’t have any specific numbered category assigned to it. Additionally, reproductive toxicity comprises categories 1 and 2, which are related to the effects on fertility or the unborn child. Although considered a different hazard, the effects on or via lactation are related to the reproductive toxicity class.

Employers have a responsibility to ensure that the most up-to-date version of the SDS is readily available for all hazardous products found in the workplace.

Is WHMIS training required?

All Canadian jurisdictions require that employers develop, implement, and maintain a worker WHMIS education and training program. WHMIS training requirements are designed to ensure workers easily recognize hazardous products and identify what makes them a hazard. 

This helps users better protect themselves and others from potential hazards associated with hazardous products. WHIMIS and its symbols aim to help employees work safely with hazardous products and know where to find information about them quickly. The ultimate goal of any WHMIS training activity should be safety. To ensure that, it is essential to receive the appropriate WHMIS training.

Do you need help with your WHMIS training identification?

Understanding and implementing WHMIS training are vitally important for maintaining a safe and healthy work environment in Canada. From being able to identify and recognize hazard classifications to accessing critical information through the use of safety data sheets, WHMIS allows workers to protect themselves and their colleagues from the potential dangers of hazardous products. 

Enhance your organization’s WHMIS training with Citation Canada’s health and safety experts at your side!

While WHMIS is a legal requirement, it is not only about compliance. It is also there to help build an understanding of potential risks and how to mitigate them daily. Making sure that your team has appropriate health & safety tools and engaging WHMIS training helps demonstrate an employer’s commitment to safety in the workplace.

If you’re looking for resources to enhance your WHMIS program or ensure your team receives industry-leading WHMIS training, Citation Canada offers a range of customizable solutions to meet your specific needs. Visit our website to learn more about our training courses and safety resources.