Hazard Classes

Physical hazard classes and associated categories defined by WHMIS include:

PHYSICAL HAZARDS
Pictogram
Hazard Classes
Hazard Descriptions
Flammable

Flame Pictogram
  • Flammable gases (Category 1), flammable aerosols (Category 1 and 2), flammable liquids (Category 1, 2 and 3), and flammable solids (Category 1 and 2)
  • Pyrophoric liquids, solids and gases (Category 1)
  • Self-heating substances and mixtures (Category 1 and 2)
  • The four classes cover products that have the ability to ignite (catch fire) easily and the main hazards are fire or explosion.
  • These products can catch fire very quickly (spontaneously) if exposed to air.
  • The products may catch fire if exposed to air. They differ from pyrophoric liquids or solids in that they will ignite only after a longer period of time or when in large amounts.
  • Substances and mixtures in contact with water emit flammable/explosive gases (Category 1, 2 and 3)
  • Self-reactive substances and mixtures (Types B, C, D, E and F)
  • Organic peroxides (Types B, C, D, E and F)
  • As the class name suggests, these products react with water to release flammable gases. In some cases, the flammable gases may ignite very quickly (spontaneously).
  • These products may react on their own to cause a fire or explosion, or may cause a fire or explosion if heated. Both the flame and the explosive pictograms are used for Type B.
  • These products may cause a fire or explosion if heated. Both the flame and the explosive pictograms are used for Type B.
Examples of flammables that may be found at work and at home include: gasoline, propane, butane, and paint thinner.

As a precaution you should:
  • Keep away from heat, hot surfaces, sparks, open flames, and other ignition sources.
  • Keep the container tightly closed.
  • Ground and bond the container and receiving equipment.
  • Take action to prevent static discharges.
  • Wear protective gloves, protective clothing, eye protection, and face protection.
  • Work in well-ventilated areas.
  • Store in properly designated areas.
Oxidizer

Flame over circle Pictogram
  • Oxidizing gases (Category 1), oxidizing liquids (Category 1, 2 and 3), and oxidizing solids (Category 1, 2 and 3)
  • The three classes cover oxidizers that may cause an explosion or fire or intensify a fire.
Examples of oxidizers that may be found at work and at home include: hydrogen peroxide, chlorine, and sodium chlorate.

As a precaution you should:
  • Keep away from heat, hot surfaces, sparks, open flames and other ignition sources.
  • Keep away from clothing and other combustible materials.
  • Wear protective gloves, eye protection, and face protection.
  • Wear fire resistant or flame retardant clothing.
  • Store in proper containers which will not rust or oxidize.
Compressed Gas

Gas Cylinder Pictogram
  • Gases under pressure
  • This class includes compressed gases, liquefied gases, dissolved gases and refrigerated liquefied gases. They are hazardous because of the high pressure inside the cylinder or container.
Examples of gases under pressure that may be found at work and at home include: oxygen, propane, acetylene, and compressed air.

As a precaution you should:
  • Handle cylinders with care; do not drop them.
  • Keep cylinders away from direct heat like furnaces or open flames.
  • Store cylinders in areas designated by your supervisor (must be well-ventilated and dry).
  • Inspect storage areas regularly for any deficiencies such as damaged or leaking cylinders and poor housekeeping.
Corrosive

Corrosion Pictogram
  • Corrosive to metals (Category 1)
  • These products may be corrosive (chemically damage or destroy) to metals. They may cause skin corrosion or serious eye damage.
Examples of corrosives that may be found at work and at home include: battery acid, nitric acid, hydrochloric acid, and hydroxide solutions.

As a precaution you should:
  • Keep containers tightly closed.
  • Handle the material only when using appropriate protective clothing.
  • Handle the material in well-ventilated areas and wear proper respiratory equipment.
Explosive

Exploding bomb Pictogram
  • Self-reactive substances and mixtures (Types A and B)
  • Organic peroxides (Types A and B)
  • These products may react on their own to cause a fire or explosion, or may cause a fire or explosion if heated.
  • These products may cause a fire or explosion if heated.
Note: WHMIS regulations do not currently include the Explosive hazard class. Explosives are covered by other legislation in Canada. However, you may see the Explosive classes listed on labels and SDSs, especially for products imported from other countries.
Examples of explosives that may be found at work include: A wide variety of chemicals which can explode under certain conditions – shock, pressure or high temperature; a smaller number are manufactured specifically for the purpose of being used as explosives.

As a precaution you should:
  • Keep the material away from incompatible materials and store in the areas designated by your supervisor.
  • Keep the material away from sources of ignition.
  • Wear the proper protective equipment and clothing, including eye, face and hand protection.
Other Physical Hazards

Are to have a GHS pictogram that is appropriate to the hazard identified.
  • Combustible dusts
  • Simple asphyxiants
  • Physical hazards not otherwise classified
  • This class is used to warn of products that are finely divided solid particles. If dispersed in air, the particles may catch fire or explode if ignited.
  • These products are gases that may displace oxygen in air and cause rapid suffocation.
  • This class is meant to cover any physical hazards that are not covered in any other physical hazard class. If a product is classified in this class, the hazard statement on the label and SDS will describe the nature of the hazard.

 

Health hazard classes and associated categories defined by WHMIS include:

HEALTH HAZARDS
Pictogram
Hazard Classes
Hazard Description
Health Hazard

Health hazard Pictogram
  • Respiratory or skin sensitization (Category 1, 1A and 1B)
  • Germ cell mutagenicity (Category 1, 1A, 1B and 2)
  • Carcinogenicity (Category 1, 1A, 1B and 2)
  • Reproductive toxicity (Category 1, 1A, 1B and 2)
  • Specific target organ toxicity – single exposure (Category 1 and 2)
  • Specific target organ toxicity – repeated exposure (Category 1 and 2)
  • Aspiration hazard (Category 1)
  • A respiratory sensitizer is a product that may cause allergy or asthma symptoms or breathing difficulties if inhaled.
  • This hazard class includes products that may cause or are suspected of causing genetic defects.
  • This hazard class includes products that may cause or are suspected of causing cancer.
  • This hazard class includes products that may damage or are suspected of damaging fertility or the unborn child (baby).
  • This hazard class covers products that cause or may cause damage to organs (e.g., liver, kidneys, or blood) following a single exposure.
  • This hazard class covers products that cause or may cause damage to organs (e.g., liver, kidneys, or blood) following prolonged or repeated exposure.
  • This hazard class is for products that may be fatal if they are swallowed and enter the airways.
As a precaution you should:
  • Avoid breathing dust or vapours.
  • Avoid contact with skin or eyes.
  • Work in well-ventilated areas.
  • Wear appropriate personal protection.
  • Store products in designated areas.
Other Health Hazards

Are to have a GHS pictogram that is appropriate to the hazard identified.
  • Health hazards not otherwise classified
  • This class covers products that are not included in any other health hazard class. If a product is classified in this class, the hazard statement will describe the nature of the hazard.
Toxic

Skull and crossbones Pictogram
  • Acute toxicity – Oral (Category 1, 2 and 3), Dermal (Category 1, 2 and 3) and Inhalation (Category 1, 2 and 3)
  • These poisonous products are fatal, toxic or harmful if inhaled, following skin contact, or if swallowed. Acute toxicity refers to effects occurring following skin contact or ingestion exposure to a single dose, or multiple doses given within 24 hours, or an inhalation exposure of 4 hours.
As a precaution you should:
  • Avoid breathing dust or vapours.
  • Avoid contact with skin or eyes.
  • Work in well-ventilated areas.
  • Wear appropriate personal protection.
  • Store products in designated areas.
Irritant

Exclamation mark Pictogram
  • Skin corrosion/irritation (Category 2)
  • Serious eye damage/irritation (Category 2 and 2A)
  • Respiratory or skin sensitization (Category 1, 1A and 1B)
  • Specific target organ toxicity – repeated exposure (Category 3)
  • This class covers products that cause severe skin burns (i.e., corrosion) and products that cause skin irritation.
As a precaution you should:
  • Avoid contact with skin or eyes.
  • Work in well-ventilated areas.
  • Wear appropriate personal protection.
  • Store products in designated areas.
Biohazardpus Infectious Materials

Round black border
  • Biohazardous infectious materials (Category 1)
  • These materials are microorganisms, nucleic acids or proteins that cause or is a probably cause of infection, with or without toxicity, in humans or animals.
As a precaution you should:
  • Avoid contamination by wearing protective equipment.
  • Handle the material only when fully protected by the proper designated equipment.
  • Handle the material in designated areas that are approved by your supervisor.

 

Environmental hazard class and associated category defined by WHMIS include:

Pictogram
Hazard Classes
Hazard Description
Environment

Dead tree/dead fish Pictogram
  • Hazardous to the aquatic environment and hazardous to the ozone layer
  • GHS also defines an Environmental hazards group. This group (and its classes) was not adopted by Canada in WHMIS 2015. However, you may see the environmental classes listed on labels and SDSs, especially for products imported from other countries.