The Workplace Hazardous Materials Information System (WHMIS) is Canada's national workplace hazard communication standard. It is a comprehensive plan for providing information on the safe use of hazardous materials used in Canadian workplaces. The key elements of the system are cautionary labelling of containers of WHMIS-controlled products, the provision of material safety data sheets (MSDSs) and worker education and site-specific training programs.

Exposure to hazardous materials can cause or contribute to many serious health effects such as effects on the nervous system, kidney or lung damage, sterility, cancer, burns and rashes. Some hazardous materials are safety hazards and can cause fires or explosions. WHMIS was created to help stop the injuries, illnesses, deaths, medical costs, and fires caused by hazardous materials.

Within WHMIS, chemicals are put into 6 different classes to identify their hazards. Within these classes, there are symbols identified with each class. These symbols are outlined below.

Class A
Compressed Gas

 Gas cylinder is under pressure and may explode if heated or damaged
 Sudden release of high pressure gas streams may puncture skin and cause fatal embolism
• Transport and handle with care
• Ensure cylinder is properly secured
• Store away from heat or fire sources
• Use appropriate regulator

Class B
Flammable and Combustible Material

 May burn or explode when heated
 Burns readily at room temperature
• Store away from Class C (oxidizing) materials
• Store away from heat, sparks and flame

Class C
Oxidizing Material

Can cause other materials to burn or explode by providing oxygen
May burn skin and eyes on contact
• Store away from Class B (flammable and combustible)
• Store away from heat, sources of ignition
• Wear recommended personal protective equipment
 

Class D – Division 1
Poisonous and Infectious Material, Immediate and Serious Toxic Effects

May cause immediate death or serious injury if inhaled, ingested, absorbed or injected into the body
• Avoid inhalation, skin, eye contact
• Wear recommended personal protective equipment
• Wash hands after use

Class D – Division 2
Poisonous and Infectious Material, Other Toxic Effects

May cause death or permanent injury following repeated or long term exposure; May irritate eyes, skin and breathing and may lead to long term lung problems and skin sensitivity; May cause liver or kidney damage, cancer, birth defects or sterility
• Avoid inhalation, skin and eye contact
• Wear recommended personal protective equipment
• Wash hands after use

Class D – Division 3
Poisonous and Infectious Material, Biohazardous Infectious Material

Contact with microbiological agents (bacteria, viruses, fungi and their toxins) may cause illness or death
• Wear recommended personal protective equipment
• Work in designated areas only
• Disinfect area after handling
• Wash hands after handling

Class E
Corrosive Material

Will burn eyes and skin on contact
Will burn respiratory tract if inhaled
• Store acids and bases separately
• Avoid inhalation and skin contact
• Wear the recommended personal protective equipment

Class F
Dangerously Reactive Material

May be unstable, reacting dangerously to jarring, compression, heat or light exposure
May burn, explode or produce dangerous gases when mixed with incompatible materials
• Store away from heat sources
• Avoid shock and friction
• Wear the recommended personal protective equipment