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WHMIS 2015 - Hazard Classes and Categories

Important Information

Canada has aligned the Workplace Hazardous Materials Information System (WHMIS) with the Globally Harmonized System of Classification and Labelling of Chemicals (GHS).

This document discusses the WHMIS requirements after the alignment of WHMIS with the GHS. Information in this document is based on the federal legislation – the amended Hazardous Products Act and the new Hazardous Products Regulations (HPR).

Health Canada is the government body responsible for making the required changes to the overall federal WHMIS-related laws. Note that WHMIS-related occupational health and safety regulations for the provinces, territories and federally regulated workplaces will also require updating.

While much is known with the federal legislation updates, legislative updates for each provincial or territorial jurisdiction may affect some of the information in this document.

The WHMIS 2015 legislation is currently in force. "In force" means that suppliers may begin to use and follow the new requirements for labels and safety data sheets (SDSs) for hazardous products sold, distributed, or imported into Canada. However, there is a transition period with various stages. At the outset of the transition period, the supplier must fully comply with either the repealed Controlled Products Regulations (WHMIS 1988) or the HPR (WHMIS 2015) for a specific controlled or hazardous product. The classification, label and (material) SDS must comply fully with the specific regulation chosen by the supplier, and not be a combination of the two.

Please refer to the following OSH Answers documents for information about WHMIS 2015:

What is a hazard group?

WHMIS 2015 applies to two major groups of hazards: physical, and health. Each hazard group includes hazard classes that have specific hazardous properties.

  • Physical hazards group: based on the physical or chemical properties of the product – such as flammability, reactivity, or corrosivity to metals.
  • Health hazards group: based on the ability of the product to cause a health effect – such as eye irritation, respiratory sensitization (may cause allergy or asthma symptoms or breathing difficulties if inhaled), or carcinogenicity (may cause cancer).

GHS also defines an Environmental hazards group. This group (and its classes) was not adopted in WHMIS 2015. However, you may see the environmental classes listed on labels and Safety Data Sheets (SDSs). Including information about environmental hazards is allowed by WHMIS 2015.


What is a hazard class?

Hazard classes are a way of grouping together products that have similar properties. Most of the hazard classes are common to GHS and will be used worldwide by all countries that have adopted GHS. Some hazard classes are specific to WHMIS 2015.

List of Hazard Classes

Physical Hazards

  • Flammable gases
  • Flammable aerosols
  • Oxidizing gases
  • Gases under pressure
  • Flammable liquids
  • Flammable solids
  • Self-reactive substances and mixtures
  • Pyrophoric liquids
  • Pyrophoric solids
  • Self-heating substances and mixtures
  • Substances and mixtures which, in contact with water, emit flammable gases
  • Oxidizing liquids
  • Oxidizing solids
  • Organic peroxides
  • Corrosive to metals
  • Combustible dusts
  • Simple asphyxiants
  • Pyrophoric gases
  • Physical hazards not otherwise classified

Health Hazards

  • Acute toxicity
  • Skin corrosion/irritation
  • Serious eye damage/eye irritation
  • Respiratory or skin sensitization
  • Germ cell mutagenicity
  • Carcinogenicity
  • Reproductive toxicity
  • Specific target organ toxicity – single exposure
  • Specific target organ toxicity – repeated exposure
  • Aspiration hazard
  • Biohazardous infectious materials
  • Health hazards not otherwise classified

Note: GHS also defines an Explosive class and the Environmental Hazards group (not mandatory). The WHMIS regulations do not currently include the Explosives hazard class. Explosives are covered by other legislation in Canada.


What is a hazard category?

Each hazard class contains at least one category. The hazard categories are assigned a number (e.g., 1, 2, etc.) Categories may also be called "types". Types are assigned an alphabetical letter (e.g., A, B, etc.). In a few cases, sub-categories are also specified. Subcategories are identified with a number and a letter (e.g., 1A and 1B).

Some hazard classes have only one category (e.g., corrosive to metals), others may have two categories (e.g., carcinogenicity (cancer)) or three categories (e.g., oxidizing liquids). There are a few hazard classes with five or more categories (e.g., organic peroxides).

The category tells you about how hazardous the product is (that is, the severity of hazard).

  • Category 1 is always the greatest level of hazard (that is, it is the most hazardous within that class). If Category 1 is further divided, Category 1A within the same hazard class is a greater hazard than category 1B.
  • Category 2 within the same hazard class is more hazardous than category 3, and so on.

There are a few exceptions to this rule. For example, for the Gases under pressure hazard class, the hazard categories are "Compressed gas", "Liquefied gas", "Refrigerated liquefied gas" and "Dissolved gas". These classes relate to the physical state of the gas when packaged and do not describe the degree of hazard.

In addition, the Reproductive Toxicity hazard class has a separate category called "Effects on or via lactation". "Effects on or via lactation" was not assigned a specific numbered category. Reproductive toxicity also has Categories 1 and 2 which relate to effects on fertility and/or the unborn child. Effects on or via lactation is considered a different, but related hazard within the Reproductive toxicity class.


What are the main concerns for each physical hazard class?

Hazard Class General Description
Flammable gases
Flammable aerosols
Flammable liquids
Flammable solids
These four classes cover products that have the ability to ignite (catch fire) easily and the main hazards are fire or explosion.
Oxidizing gases
Oxidizing liquids
Oxidizing solids
These three classes cover oxidizers, which may cause or intensify a fire or cause a fire or explosion.
Gases under pressure This class includes compressed gases, liquefied gases, dissolved gases and refrigerated liquefied gases.
Compressed gases, liquefied gases and dissolved gases are hazardous because of the high pressure inside the cylinder or container. The cylinder or container may explode if heated. Refrigerated liquefied gases are very cold and can cause severe cold (cryogenic) burns or injury.
Self-reactive substances and mixtures These products may react on their own to cause a fire or explosion, or may cause a fire or explosion if heated.
Pyrophoric liquids
Pyrophoric solids
Pyrophoric gases
These products can catch fire very quickly (spontaneously) if exposed to air.
Self-heating substances and mixtures These products may catch fire if exposed to air. These products 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 which, in contact with water, emit flammable gases 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).
Organic peroxides These products may cause a fire or explosion if heated.
Corrosive to metals These products may be corrosive (chemically damage or destroy) to metals.
Combustible dust 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.
Simple asphyxiants These products are gases that may displace oxygen in air and cause rapid suffocation.
Physical hazards not otherwise classified This class is meant to cover any physical hazards that are not covered in any other physical hazard class. These hazards must have the characteristic of occurring by chemical reaction and result in the serious injury or death of a person at the time the reaction occurs.If a product is classified in this class, the hazard statement on the label and SDS will describe the nature of the hazard.

What are the main concerns for each health hazard class?

Hazard Class General Description
Acute toxicity These 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.
Acute toxicity could result from exposure to the product itself, or to a product that, upon contact with water, releases a gaseous substance that is able to cause acute toxicity.
Skin corrosion/irritation This class covers products that cause severe skin burns (i.e., corrosion) and products that cause skin irritation.
Serious eye damage/eye irritation This class covers products that cause serious eye damage (i.e., corrosion) and products that eye irritation.
Respiratory or skin sensitization A respiratory sensitizer is a product that may cause allergy or asthma symptoms or breathing difficulties if inhaled. Skin sensitizer is a product that may cause an allergic skin reaction.
Germ cell mutagenicity This hazard class includes products that may cause or are suspected of causing genetic defects (permanent changes (mutations) to body cells that can be passed on to future generations).
Carcinogenicity This hazard class includes products that may cause or are suspected of causing cancer.
Reproductive toxicity This hazard class includes products that may damage or are suspected of damaging fertility or the unborn child (baby).
Note: There is an additional category which includes products that may cause harm to breast-fed children.
Specific target organ toxicity – single exposure This hazard class covers products that cause or may cause damage to organs (e.g., liver, kidneys, or blood) following a single exposure.
This class also includes a category for products that cause respiratory irritation or drowsiness or dizziness.
Specific target organ toxicity – repeated 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.
Aspiration hazard This hazard class is for products that may be fatal if they are swallowed and enter the airways.
Biohazardous infectious materials 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.
Health hazards not otherwise classified This class covers products that are not included in any other health hazard class. These hazards have the characteristic of occurring following acute or repeated exposure and have an adverse effect on the health of a person exposed to it - including an injury or resulting in the death of that person.  If a product is classified in this class, the hazard statement will describe the nature of the hazard.

How will I know what hazard class or category is assigned to a hazardous product?

Suppliers must evaluate products that are covered by the Hazardous Products Act against specific criteria as required by the Hazardous Products Regulations. If the product meets any of the criteria for a hazard class, it is known as a hazardous product. All hazardous products must be labelled according to the regulations, and must have a corresponding Safety Data Sheet (SDS). The hazard class and category will be provided in Section 2 (Hazard Identification) of the SDS. Each hazard class or category must use specific pictograms and other label elements to indicate the hazard that is present, and what precautionary measures must be taken. Use the information provided by the label and SDS to be informed and to know how to safely use, handle, store and dispose of the hazardous product.

See the OSH Answers below for more information:

Document last updated on March 7, 2016

Disclaimer

Although every effort is made to ensure the accuracy, currency and completeness of the information, CCOHS does not guarantee, warrant, represent or undertake that the information provided is correct, accurate or current. CCOHS is not liable for any loss, claim, or demand arising directly or indirectly from any use or reliance upon the information.