When authoring a WHMIS MSDS the WHMIS Classification Checklist is an essential part of the classification process of a chemical product. All chemical products sold or used in the Canadian workplace are regulated under WHMIS and for this reason must have the proper WHMIS classifications.  The WHMIS Checklist provides the 6 WHMIS classes along with the requirements for each class and the 8 associated WHMIS symbols.

Going through the checklist in order of class, the first is Class A – Compressed Gas. To be a compressed gas a chemical needs to be a liquid in an aerosol container, or a gas under a pressure of > 40psi within a cylinder. A very helpful thing about the checklist is it states where in a WHMIS MSDS the information used to classify the chemical may be found. For example when classifying a chemical under Class A the information May be located in MSDS section(s): Physical Data, Fire and Explosion Data.

Class B – Flammable/Combustible Material has 6 subclasses. These subclasses are distinguished by their physical form (solid, liquid, gas), flashpoint values (°C), and conditions of cause for the fire /combustion.

Class C – Oxidizing Material is a chemical which contributes to the combustion of another material whether or not the product itself is combustible, or is organic peroxide that contains the double bonded oxygen structure.

Class D – Poisonous and Infectious Material has 3 subclasses. Class D1 are materials causing immediate and serious toxic effects.  To be classified under this subclass a chemical must be under the TDG Classes stated, or fall within the oral, dermal or inhalation toxicity ranges given. Class D2 are materials causing other toxic effects and must have at least one of the effects listed. Class D3 are biohazardous infectious materials which are organisms that have been shown to cause or reasonably believed to cause disease in persons or animals, or organisms classified into Risk Group 2, 3, and 4 as determined by the WHO or MRCC.

Class E – Corrosive Material has a pH ? 2.0 or ? 11.5, will cause irreversible damage/necrosis of skin tissue resulting in burns, corrodes SAE 1020 steel or aluminum type 7075-T6, or be classified under TDG Class 8 (or 2.4 for a gas).

Class F – Dangerously Reactive Material must have vigorous polymerization, decomposition, or condensation, become self-reactive under conditions of shock, increased pressure, or temperature, or react vigorously with water to release a toxic gas.

WHMIS is an identification system that helps you recognize the hazards associated with handling chemicals in your workplace. Designed for agricultural workers, Making WHMIS Work covers the basics of WHMIS and introduces the four questions that all workers need to know.