GHS Course page 5 | Industrial & Construction Safety Solutions



Health Hazards

The WHMIS health hazard classes are:

  • 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

Health Hazard Pictogram


Health Hazard Pictogram


The health hazard pictogram is used for a number of classes:

Respiratory or skin sensitization

  • A respiratory sensitizer may cause allergy or asthma symptoms, or breathing difficulties if inhaled. Remember that the Skin sensitization category of this class uses the exclamation mark pictogram.

Germ Cell Mutagenicity

  • May cause genetic defects or is suspected of causing genetic defects. Mutations can lead to birth defects or cancer.


  • May cause cancer or is suspected of causing cancer.

Reproductive toxicity

  • May damage fertility or the unborn child, or is suspected of damaging fertility or the unborn child. May cause harm to breast-fed children.

Specific target organ toxicity – single exposure

  • Causes or may cause damage to organs through single – one time exposure.

Specific target organ toxicity – repeated exposure

  • Causes or may cause damage to organs through repeated or prolonged exposure.

Aspiration hazard

  • May be fatal if swallowed and enters the airways.

Exclamation Mark Pictogram


Exclamation Mark Pictogram


Like the health hazard pictogram, the exclamation mark pictogram is used for a number of classes:

Acute toxicity (Cat. 4) 

  • Harmful if swallowed. Harmful in contact with skin. Harmful if inhaled.

Skin corrosion/irritation (Cat. 2)

  • Causes skin irritation.

Serious eye damage/eye irritation (Cat. 2)

  • Causes serious eye irritation.

Respiratory or skin sensitization (Cat. 1)

  • May cause an allergic skin reaction.

Specific target organ toxicity – Single exposure (Cat. 3)

  • May cause respiratory irritation. May cause drowsiness or dizziness.

Specific Target Organ Toxicity – Single Exposure


Single Exposure Picture


Specific target organ toxicity – single exposure is the hazard class for products that may cause significant, non-lethal damage to organs following a single exposure. In addition, products that may cause respiratory tract irritation and/or drowsiness or dizziness are covered in this class.

These products will be labelled with either the health hazard or the exclamation mark pictogram. For example, toluene may cause drowsiness or dizziness. 

Like the Acute toxicity class, read the label and look for the pictogram, signal word, and hazard statement to determine the severity level of the hazard.

Skin & Eye


Skin and Eye Picture


These products can cause effects ranging from severe skin burns and eye damage (corrosion) to skin irritation or eye irritation.

The corrosion and exclamation mark pictograms are used to indicate the following classes:

  • Skin corrosion/irritation 
  • Serious eye damage/eye irritation 

Corrosive to metals class also uses the pictogram on the left. 

The exclamation mark is also used for products that can cause allergic skin reactions. This hazard class is known as Skin Sensitization. The signal word is Warning and the hazard statement is May cause an allergic skin reaction. Methyl methacrylate is an example of a product that causes skin sensitization.

Using the Label

These products can cause severe health effects or even death if you breathe them in, if they come in contact with your skin, or if they are swallowed. The acute toxicity hazard class uses the skull and crossbones or the exclamation mark pictogram to indicate products that can cause adverse effects following brief exposure. The hazard statements for this class will help indicate the seriousness of the effects, statements with Fatal are more serious than Toxic, and Toxic is more serious than harmful. How do you know if the product is classified as fatal, toxic or harmful? Read the label for more information, including the hazard statements.

For example:

Acute Toxicity

  • Inhalation (Categories 1 and 2) will be labelled with the skull and crossbones pictogram and the signal word Danger. In this case, you will see the hazard statement Fatal if inhaled. 

Acute Toxicity 

  • Inhalation (Category 3) will be labelled with the skull and crossbones pictogram and the signal word Danger and the hazard statement Toxic if inhaled.

Acute Toxicity

  • Inhalation (Category 4) will be labelled with the exclamation mark and the signal word 

Warning. The hazard statement will be Harmful if inhaled.

Combining the Elements


Combining Elements



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