Have your heard of WHMIS? It stands for the Workplace Hazardous Materials Information System. It is a Canada-wide system enacted in federal, provincial and territorial legislation. Its objective is to protect the health and safety of workers by promoting access to information on hazardous products, substances and mixtures used in the workplace.

The key elements of WHMIS are:

  • The classification of hazardous products
  • Labelling (supplier and workplace labels)
  • Safety data sheets (supplier and workplace SDSs)
  • Worker education and training programs

In this article, our hazardous waste management specialists provide an overview of the first element—the classification of hazardous products. Read on for more information about the development of the classification system and the responsibilities of people who transport and handle these types of products.

WHMIS classification of substances and mixtures

The GHS (Globally Harmonized System of Classification and Labelling of Chemicals) provides a consistent framework for classifying the hazards contained in products and communicating them effectively using labels and safety data sheets. 
Its classification system for chemical substances and mixtures was developed by two groups of experts: one from the OECD (Organization for Economic Co-operation and Development) and the other made up of experts in the transport of dangerous goods. 

The first group focused on health and environmental considerations, and the second on physical hazards. That’s partly why the GHS has divided the classes into two major groups:  physical hazards and health hazards.

Physical hazards

  1. Flammable gases
  2. Flammable aerosols
  3. Oxidizing gases
  4. Gases under pressure
  5. Flammable liquids
  6. Flammable solids
  7. Self-reactive substances and mixtures
  8. Pyrophoric liquids
  9. Pyrophoric solids
  10. Self-heating substances and mixtures
  11. Substances and mixtures that emit flammable gases when in contact with water 
  12. Oxidizing liquids
  13. Oxidizing solids
  14. Organic peroxides
  15. Substances and mixtures that are corrosive to metals
  16. Combustible dusts
  17. Simple asphyxiants
  18. Pyrophoric gases
  19. Physical hazards not otherwise classified

Health hazards

  1. Acute toxicity
  2. Skin corrosion/irritation
  3. Serious eye damage/eye irritation
  4. Respiratory or skin sensitization
  5. Germ cell mutagenicity
  6. Carcinogenicity
  7. Reproductive toxicity
  8. Specific target organ toxicity – single exposure
  9. Specific target organ toxicity – repeated exposure
  10. Aspiration hazard
  11. Biohazardous infectious materials
  12. Health hazards not otherwise classified

Pictograms that represent hazard classes and categories

A pictogram system has been established so that hazardous products can be identified more easily.

Each pictogram represents a different category of hazard. Note that some classes of hazards are found in more than one category.


  • Flammable gases
  • Flammable aerosols
  • Flammable liquids
  • Flammable solids
  • Self-reactive substances and mixtures
  • Pyrophoric liquids
  • Pyrophoric solids
  • Self-heating substances and mixtures
  • Substances and mixtures that emit flammable gases when in contact with water
  • Organic peroxides
  • Pyrophoric gases

Flame over circle

  • Oxidizing gases
  • Oxidizing liquids
  • Oxidizing solids

Exploding bomb

  • Self-reactive substances and mixtures
  • Organic peroxides


  • Substances and mixtures that are corrosive to metals

  • Skin corrosion/irritation

  • Serious eye damage/eye irritation

Gas cylinder

  • Gases under pressure (compressed gas, liquefied gas, refrigerated liquefied gas and dissolved gas)

Skull and crossbones

  • Acute toxicity – oral 
  • Acute toxicity – dermal 
  • Acute toxicity – inhalation 

Exclamation mark

  • Acute toxicity – oral 
  • Acute toxicity – dermal 
  • Acute toxicity - inhalation
  • Skin corrosion/irritation
  • Serious eye damage/eye irritation
  • Skin sensitization
  • Specific target organ toxicity – single exposure

Health hazard

  • Respiratory sensitization

  • Germ cell mutagenicity

  • Carcinogenicity

  • Reproductive toxicity

  • Specific target organ toxicity – single exposure 

  • Specific target organ toxicity – repeated exposure  

  • Aspiration hazard

Biohazardous infectious materials    

  • Biohazardous infectious materials

Steps for classifying a product or mixture

There are three steps experts use to classify hazards:

  1. Identify relevant data on the dangers of a substance or mixture
  2. Review the data to assess the danger posed by a substance or mixture
  3. Evaluate the data using the established hazard classification criteria to determine whether the substance or mixture should be classified and the degree of danger, if applicable

Supplier, employer and employee responsibilities regarding hazardous products

WHMIS places certain responsibilities on suppliers of hazardous products and the employers and employees who handle them.

Here is an overview of the responsibilities:

Supplier responsibilities

Suppliers who manufacture, import, distribute or sell hazardous products must:

  • Determine which of their products must be classified as hazardous

  • Obtain, prepare and transmit information regarding their hazardous products in the form of labels and safety data sheets (SDSs)
  • Keep information on their hazardous products up to date
  • Keep required documentation (including copies of labels and SDSs and a list of purchases and sales)

Employer responsibilities 

Employers who purchase, use or manufacture hazardous products for their own use also have specific responsibilities:

  • Ensure that the hazardous products used, transferred, stored, handled or disposed of in the workplace are properly labelled
  • Obtain SDSs and make them available to workers
  • Ensure that workers who are exposed or likely to be exposed to hazardous products receive the necessary training and information 

Employee responsibilities

Employees who use hazardous products in the course of their work also have a role to play in preventing incidents that involve goods that are classified as dangerous:

  • Participate in the hazardous products training and information program
  • Take the appropriate measures to protect oneself and one’s colleagues 
  • Actively participate in identifying and eliminating hazards

Leave your hazardous waste management to EBI Enviro Urgence

Now that you know more about the classification of hazardous products, you can imagine how complex hazardous waste management is, from manufacturing and transportation to disposal. It’s a major concern that must be taken very seriously in order to protect the environment.

If you are part of an organization that is looking for a trustworthy company to dispose of its hazardous products in compliance with regulations, contact EBI Enviro Urgence. You can rest assured that your hazardous waste (liquids, solids, containers, etc.) will be handled with care and will no longer pose any danger to the environment or the population.