WHMIS Training in Canada

WHMIS Hazard Classes

 

Since the Hazardous Products Regulations (HPR) replaced the Controlled Products Regulations in Canada, WHMIS primarily uses the United Nations Globally Harmonized System (GHS) pictograms. These pictograms—easy to recognize by their red diamond border—draw workers’ attention and indicate the hazards posed by products. These hazards are divided into two groups: physical hazards and health hazards.

Physical Hazards

 

Physical hazards are hazards that can cause damage to the immediate environment of the products through mechanical or chemical action. Physical hazards can also severely injure workers who are exposed. WHMIS groups physical hazards under five pictograms, plus hazards that do not require a pictogram.

Exploding Bomb

This pictogram warns the worker that the product presents an explosion risk—i.e., a chemical reaction generating gases at a rate, temperature, and pressure likely to cause damage.

Explosives are not regulated under WHMIS because they are governed in Canada by the Explosives Act. However, some substances that are not “explosives” under that Act can still present explosion hazards. The following WHMIS hazard classes require the exploding bomb pictogram:

• Self-reactive substances and mixtures – Types A and B
• Organic peroxides – Types A and B

When this pictogram appears on a product, all necessary precautions must be taken to prevent detonation or deflagration. Protect the product from heat, flames, sparks, static electricity, and shock. It must be protected from light and kept cool—often refrigerated in an explosion-proof refrigerator—and accessible only to trained personnel. Quantities stored in the workplace should be kept to a minimum.

Gas Cylinder

 

The gas cylinder pictogram is used when a product is a pressurized container, except for aerosols. It indicates the contents are under pressure and there is a significant risk of damage if the container is opened, damaged, or mishandled.

Compressed gas cylinders often carry this pictogram. If a cylinder fails, it can literally rocket and cause severe damage along its path. WHMIS hazard classes that require this pictogram include:

• Gases under pressure
  • Compressed gas
  • Liquefied gas
  • Refrigerated liquefied gas
  • Dissolved gas
• Chemicals under pressure

When handling, transporting, or storing a product with the gas cylinder symbol, avoid situations that could lead to container rupture. Cylinders must be kept upright and secured to prevent tipping. Keep containers away from heat and direct sunlight to avoid internal pressure increases that could lead to an explosion.

Flame

The flame pictogram covers the widest range of hazard classes in WHMIS. In general, it indicates a fire risk.

There are 11 distinct hazard classes associated with the flame pictogram:

• Flammable gases – Categories 1A, 1B; Chemically unstable gas A and B; and 1A Pyrophoric gas
• Aerosols – Categories 1 and 2
• Flammable liquids – Categories 1, 2, and 3
• Chemicals under pressure – Categories 1 and 2
• Flammable solids – Category 1
• Pyrophoric liquids
• Pyrophoric solids
• Self-heating substances and mixtures
• Substances and mixtures which, in contact with water, emit flammable gases
• Self-reactive substances and mixtures – Types B, C, D, E, F
• Organic peroxides – Types B, C, D, E, F

When handling products with the flame pictogram, keep them away from open flame, heat sources, and sparks. Take measures to avoid shock and static electricity. Avoid mixing these products with oxidizers, as such mixtures can greatly increase ignition risk.

Some of these substances require specific precautions—for example, pyrophoric liquids and solids must be kept under inert atmosphere. Substances that emit flammable gases on contact with water should be kept dry (e.g., in a desiccator) or submerged in oil to prevent contact with water or ambient humidity.

Storage for products with the flame pictogram is complicated by the wide range of hazard classes involved. Not all substances bearing the flame symbol are mutually compatible. Self-heating substances, for example, must not be stored with flammables. Because storage can be challenging, a more detailed assessment is often required to store these substances safely. In practice, it can be easier to base storage on Transport of Dangerous Goods (TDG) classifications.

Flame Over Circle

The flame over circle pictogram represents oxidizing products. These are not themselves combustible but can cause or intensify a fire because they supply oxygen. Three hazard classes use this pictogram:

• Oxidizing gases
• Oxidizing liquids
• Oxidizing solids

Products with this pictogram must be kept away from flammables and combustibles. In a fire, if flames reach oxidizers, the fire will accelerate and intensify—something to avoid at all costs. Contact between oxidizers and flammables should also be prevented because it can cause a fire or even an explosion. Some oxidizers are so powerful they can ignite simple combustible materials (e.g., wood, paper) on contact. For this reason, oxidizers should not be kept in cardboard boxes or on wooden pallets and shelving.

Corrosion

The corrosion pictogram is the only WHMIS pictogram used for both physical hazards and health hazards. In this section, we address only physical hazards; health hazards are covered later.

For physical hazards, this pictogram represents products that damage metals through chemical action. One hazard class uses this pictogram:

– Corrosive to metals

When handling a substance corrosive to metals, avoid contact with metals. Clean up spills promptly to prevent the substance from reaching and attacking nearby metal structures. Ensure the storage or transfer container is corrosion-resistant. Do not store these substances in metal containers, which could fail and cause a spill.

Another key point: substances under the corrosion pictogram can be acidic, basic, or neutral/without pH. Acids and bases are incompatible. Storage must therefore keep these substances separated: mixing an acid and a base can cause a violent exothermic reaction. Heat generation can start a fire and eject unneutralized corrosives in all directions, multiplying harm and risk. Safe handling should prevent mixing—or, at minimum, control the reaction if mixing is required.

Hazards Without Pictograms

Several WHMIS physical hazard classes—though hazardous—do not require a pictogram. These include:

• Simple asphyxiants
• Combustible dusts
• Flammable gases – Category 2
• Aerosols – Category 3
• Flammable liquids – Category 4
• Flammable solids – Category 2
• Self-reactive substances and mixtures – Type G
• Organic peroxides – Type G

When handling a product without a pictogram, check the label to see whether it falls into any of these hazard categories so you can take appropriate protective measures.

Physical Hazards Not Otherwise Classified (PHNOC)

 

One last physical hazard class deserves mention: Physical Hazards Not Otherwise Classified (PHNOC). This class allows suppliers to communicate a product-specific physical hazard that is not otherwise covered in the regulation. For example, a product that makes surfaces extremely slippery and increases the risk of falls when spilled.

There is no specific pictogram for PHNOC. However, in Canada it is permissible to use a WHMIS pictogram to warn of a hazard if it is appropriate. For example, a PHNOC that could lead to a fire may be labeled with the flame pictogram.

Health Hazards

 

Health hazards are hazards that affect human health. Effects can be immediate or long-term, localized or systemic, and sometimes lethal. WHMIS groups health hazards under five pictograms, plus hazards that do not require a pictogram.

Corrosion

As noted above, this pictogram indicates both physical and health hazards. Here we address health hazards.

For health hazards, this pictogram informs workers that the product can cause corrosion of the skin, eyes, or even respiratory tract. Corrosion is characterized by irreversible damage such as necrosis, burns, ulceration, bleeding, and blistering.

It’s important to know that acids and bases do not affect skin in the same way. Acid exposure causes immediate pain. Strong bases saponify skin—essentially turning skin into soap—so the reaction may not be painful at first even though damage is underway.

WHMIS health hazard classes using this pictogram include:

• Skin corrosion – Categories 1A, 1B, 1C
• Serious eye damage – Category 1
• Health hazards not otherwise classified – Corrosion – Category 1 (for respiratory tract corrosion)

Whether acidic or basic, when this pictogram is present, body and eyewash showers must be near areas where these products are handled. Installation should meet ANSI Z358.1-2014. Use appropriate PPE (e.g., gloves, safety goggles) to reduce the risk of contact.

For storage, the considerations discussed for “corrosive to metals” also apply here. Because corrosives may be acidic or basic, pay close attention to incompatibilities.

Skull and Crossbones

This pictogram warns that the product has acute toxicity. Acute toxicity refers to adverse effects, up to and including death, following a single exposure (or multiple exposures within 24 hours).

WHMIS considers ingestion, inhalation, and dermal contact as exposure routes. For inhalation, exposure can be to gas, vapor, or dusts/mists. Note that a dermally toxic product can be fatal without leaving visible marks or burns on the skin. Some products can also release a toxic gas when they contact water.

Toxicity criteria include LD50 (lethal dose for 50% of a population) and LC50 (lethal concentration for 50%). The lower the dose required to poison, the more dangerous the product.

WHMIS health hazard classes using this pictogram include:

• Acute toxicity – oral – Categories 1, 2, 3
• Acute toxicity – dermal – Categories 1, 2, 3
• Acute toxicity – inhalation – Categories 1, 2, 3

As with corrosives, when this pictogram is present, body and eyewash showers must be near areas where these products are handled. Take all measures to minimize exposure.

Store toxic products in a cool, well-ventilated area. Keep them away from oxidizers, strong oxidizing agents, and any incompatible products. Also keep them away from heat sources and areas with high fire risk.

Health Hazard

This pictogram designates products that seriously harm health. It is used for seven WHMIS health hazard classes:

• Respiratory sensitization
• Germ cell mutagenicity
• Carcinogenicity
• Reproductive toxicity – Categories 1A, 1B, 2
• Specific target organ toxicity (single exposure) – Categories 1 and 2
• Specific target organ toxicity (repeated exposure)
• Aspiration hazard

Because this pictogram covers several hazard classes, it’s essential to read the label and consult the Safety Data Sheet (SDS) to know which hazard(s) apply to your task.

Except for STOT (single exposure) and aspiration hazard, these are typically long-term health effects. Use appropriate PPE when handling these products, as damage may appear only after years. Again, reducing exposure is the priority.

Products with this pictogram should be stored in a cool, well-ventilated area, away from your other hazardous products.

Exclamation Mark

This pictogram indicates a product that can harm health. WHMIS classes and categories associated with the exclamation mark include:

• Acute toxicity – oral – Category 4
• Acute toxicity – dermal – Category 4
• Acute toxicity – inhalation – Category 4
• Skin irritation – Category 2
• Eye irritation – Category 2A
• Skin sensitization
• Specific target organ toxicity (single exposure) – Category 3
  • Narcotic effects
  • Respiratory tract irritation

Because this pictogram covers multiple hazards, read the label and consult the SDS to understand the specific risks you face. Protection differs between a harmful product, an irritant, and a sensitizer.

Products with this pictogram should be stored in a cool, well-ventilated place, away from other hazardous products.

Biohazardous Infectious Materials

The Biohazardous Infectious Materials pictogram is unique to Canada, which is why it does not use a red diamond border like other WHMIS pictograms. Always read the labels carefully to understand the specific infectious hazard, as hazard statements vary by agent.

Hazards Without Pictograms

A few WHMIS health hazard classes—though hazardous—do not require a pictogram. These include:

• Eye irritation – Category 2B
• Reproductive toxicity – Effects on or via lactation

Because some hazards do not require pictograms, you should always read the product label before use to understand the hazard(s) you may be exposed to.

Health Hazards Not Otherwise Classified (HHNOC)

Finally, another health hazard class must be mentioned: Health Hazards Not Otherwise Classified (HHNOC). This class allows communication of a product-specific health hazard not otherwise addressed in the regulation. There is no specific pictogram for HHNOC. However, in Canada you may use an appropriate WHMIS pictogram to warn of a hazard.

As noted above, for respiratory tract corrosion you may classify the product as “Health hazards not otherwise classified – Corrosion – Category 1” and use the corrosion pictogram.