What Do WHMIS Symbols Mean?

Canada's national system for hazardous material communication, the WHMIS, or Workplace Hazardous Materials Information System, was implemented to label containers of controlled products, create material safety data sheets and educate workers. The eight WHMIS symbols are circular icons with corresponding classes.

Class A: Compressed Gas

According to the website WorkSafeBC, items that have been classed “A” by the WHMIS contain compressed gases, dissolved gases and gases liquefied by compression or refrigeration. The symbol for Class A is a hydrogen tank.

Class B: Flammable and Combustible Material

Items such as solids, liquids or gases that can catch fire if exposed to a spark or open flame belong to Class B of the WHMIS. The Class B symbol is a black flame with a mirrored white flame within the original black flame.

Class C: Oxidizing Material

Class C materials, according to the WHMIS, are any materials that will further add to the risk of fire when contacted by flammable or combustible materials. The symbol for a Class C is a circle with Class B's fire symbol engulfing it.

Class D: Poisonous and Infectious Material

Class D items are divided by the WHMIS into three divisions, which include Division 1, or materials that cause immediate toxic effect such as sodium cyanide or hydrogen sulphide; Division 2, or materials that can cause other toxic effects such as long-term health effects over a prolonged period of exposure; and Division 3, or biohazardous infectious materials that may contain a disease-carrying organism.

The respective symbols for items with WHMIS Classes D-1, D-2 and D-3 items include a skull and crossbones, a small, black circle beneath a “T,” and the universal biohazardous symbol, which is a circle surrounded by three larger semicircles.

Class E: Corrosive Material

Symbolized by a vial spilling droplets on both a block and a human hand with lines emanating from the burn, WHMIS Class E items are any materials, such as sodium hydroxide, hydrochloric acid and nitric acid, that can eat through metal or hurt human skin due to caustic or acidic material.

Class F: Dangerously Reactive Material

Products that may self-react when exposed to physical shock or increasing pressure, and may implode or emit toxic gas, are deemed Class F by the WHMIS. The symbol for Class F items is a large R with a vertical vial in the middle that emanates vertical rays.