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.
Most pictograms have a red, diamond-shaped border around a symbol. The symbol inside the red border represents the potential hazard. WHMIS pictograms comprise both the red border and the symbol within it. Each pictogram is assigned to specific hazard classes or categories.
What are the WHMIS hazard groups?
WHMIS deals with two main groups of hazards: physical hazards and health hazards. Each group includes various hazard classes that have specific hazardous properties.
- Physical hazards refer to physical or chemical properties of the product that make it hazardous, such as flammability, reactivity, or corrosivity; and
- Health hazards are based on the product’s ability to cause a health effect, such as respiratory sensitization, eye irritation, or carcinogenicity.
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.
What are the WHMIS physical hazard classes?
| 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. |
What are the WHMIS health hazard classes?
| 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 an 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 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. 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.
There are some exceptions to the identification system for hazard categories. For instance, the hazard categories for gases under pressure are “compressed gas,” “liquefied gas,” “refrigerated liquefied gas,” and “dissolved gas.” These categories are based on the physical state of the gas when it’s packaged and do not provide any information about the degree of danger that the gas poses.
The hazard class of reproductive toxicity has a separate subcategory known as “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.
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. 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 hazardous. This helps users better protect themselves and others from potential dangers associated with hazardous products. WHIMIS also aims 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 to improve worker safety. To ensure that, it is essential to receive appropriate WHMIS training and education regularly.
HRdownloads provides immersive WHMIS training courses and hundreds of safety documents that can be updated and branded at your fingertips. Stay safe while working with hazardous products by providing the right training and compliant policies. Speak with one of our HR experts today about tailoring a WHMIS training program to your organization at a time convenient for you! Book your free demo today!