WHMIS, SDSs and Dangerous-Material Handling
Key Takeaways
WHMIS combines classification, labels, SDSs and worker education/training.
The amended-HPR transition ended December 14, 2025.
A workplace label identifies the product, precautions and SDS availability.
Same-shift exclusive-control exceptions still require clear product identification.
WHMIS 2015 & The Globally Harmonized System (GHS)
The Workplace Hazardous Materials Information System (WHMIS 2015) incorporates the Globally Harmonized System (GHS) into Canadian law.
Hazard Classification
WHMIS 2015 classifies hazardous substances into two primary groups:
- Physical Hazards: Hazards based on physical/chemical properties (flammability, compressed gases, corrosiveness to metals, self-reactives).
- Health Hazards: Hazards based on physiological harm (acute toxicity, carcinogenicity, skin corrosion, respiratory sensitization).
Core Exam Rule: In WHMIS 2015 / GHS, lower category numbers generally indicate greater severity where a class uses numerical categories (most severe). Higher category numbers (Category 2, 3, 4) represent lower hazard severity. This is the opposite of the NFPA 704 fire diamond, where 4 is the most severe.
WHMIS 2015 Pictograms
WHMIS 2015 uses red square-set-on-point (diamond) borders around black symbols on a white background (except Biohazardous Infectious Materials, which retains its black circular border):
| Pictogram | Hazard Classes & Power Plant Examples |
|---|---|
| Exploding Bomb | Self-reactives and organic peroxides; explosives are excluded from WHMIS supplier requirements and regulated separately. |
| Flame | Flammable gases, liquids, solids, aerosols; pyrophorics (fuel oil, natural gas, diesel, solvents). |
| Flame Over Circle | Oxidizing gases, liquids, solids (oxygen cylinders, sodium hypochlorite, chlorine). |
| Gas Cylinder | Gases under pressure: compressed, liquefied, dissolved (, compressed air, propane). |
| Corrosion | Corrosive to metals, skin corrosion/burns, serious eye damage (caustic soda , sulfuric acid ). |
| Skull & Crossbones | Acute toxicity: fatal or toxic via oral, dermal, or inhalation routes (chlorine gas, concentrated biocides). |
| Health Hazard | Carcinogenicity, germ cell mutagenicity, respiratory sensitization, target organ toxicity (asbestos, benzene, hydrazine). |
| Exclamation Mark | Less severe health hazards: skin/eye irritation, acute toxicity Cat 4, narcotic effects. |
| Environment | Aquatic environmental hazards (not mandatory under Canadian federal WHMIS, but widely used). |
| Biohazardous | Infectious materials, viruses, bacteria (sewage, contaminated cooling tower water with Legionella). |
Safety Data Sheets (SDSs) & Workplace Labels
Safety Data Sheets (SDSs)
An SDS is a 16-section standardized technical document detailing chemical hazards and precautions:
- Mandatory Availability: SDSs must be readily accessible to all operating personnel on all shifts (physical binders or unhindered electronic terminals).
- Update Frequency: Chemical suppliers must update an SDS within 90 days of discovering significant new hazard data.
- Key Sections for Power Engineers:
- Section 4 (First-Aid Measures): Immediate treatment for exposure (eye flushing, inhalation care).
- Section 5 (Fire-Fighting Measures): Extinguishing media, combustion hazards, and firefighter PPE.
- Section 8 (Exposure Controls / Personal Protection): Occupational exposure limits (OELs/TLVs) and required PPE.
- Section 10 (Stability & Reactivity): Incompatible chemicals, hazardous decomposition products, and runaway reactions.
Workplace Labels vs. Supplier Labels
- Supplier Labels: Affixed by the manufacturer/distributor. Must have: Product identifier, supplier identifier, pictograms, signal word (DANGER or WARNING), hazard statements, precautionary statements, and supplemental info in English and French.
- Workplace Labels: Applied when a product is decanted into a secondary container, compounded on site, or when a supplier label is damaged. Exception: Immediate use can be exempt from a workplace label. The separate same-shift exception requires exclusive control by the decanting worker and clear product identification; it does not permit an unidentified shared container.
- Three Mandatory Workplace Label Elements: (1) Product identifier matching the SDS, (2) Safe handling precautions (including PPE), and (3) A statement indicating that an SDS is available.
Current WHMIS and safe storage
Health Canada states that the transition for the amended Hazardous Products Regulations ended December 14, 2025. Products must use the applicable amended classifications, labels and safety data sheets. “WHMIS 2015” is a familiar historical name, but it does not freeze the system at its original requirements. Read the current SDS and label; a training certificate does not replace product-specific instruction.
Use SDS Section 7 for handling/storage and Section 10 for incompatibilities. Segregate incompatible chemicals even if the containers fit conveniently in the same cabinet. Acids and bases can react with substantial heat. Oxidizers can intensify fires when mixed with fuels or organic material. Hypochlorite must not contact acid because toxic chlorine can be released. Keep compressed cylinders secured, protect valves and use the correct handling equipment. Do not improvise adapters or use oil on oxygen-service equipment.
Maintain legible identification, closed compatible containers and approved secondary containment. A manufacturer's shipping container, a small day tank and a portable sample bottle have different handling arrangements. Check ventilation, temperature restrictions and ignition controls before moving a product. Never identify a chemical by tasting or deliberately smelling it. Do not rely on odour to determine whether a hazardous atmosphere is safe.
A chemical-transfer decision
An operator pours treatment chemical into an unlabelled bottle and leaves it for the next shift. Neither immediate use nor exclusive same-shift control applies. The bottle needs the required workplace identification and information before it is left in service. The receiving operator must be able to connect the identifier to the SDS and safe handling precautions. Guessing from liquid colour risks mixing incompatible substances.
Before a planned transfer, confirm the source and receiving tank identities, available capacity, hose/pump compatibility and spill controls. Review the written procedure, communication and emergency isolation arrangements. For corrosive chemicals, confirm appropriate eye/face protection and emergency washing access. Follow the product-specific dilution procedure; do not improvise a mixing sequence or neutralization response from a generic chemistry equation.
Exposure or loss of containment
Raise the alarm and protect people first. Use the emergency plan and SDS first-aid and accidental-release instructions. Response actions depend on the substance, concentration, amount and responder competence. A small spill kit does not authorize approaching an unknown vapour cloud. Keep notification concurrent with safe response; do not wait for cleanup to finish before making legally required reports. Preserve chemical identity information for responders without exposing yourself to retrieve a document.
Source notes
Official scope and technical references checked 2026-10-17: Reference 1; Reference 2; Reference 3.
A chemical in the plant has a WHMIS 2015 / GHS Flammable Liquid classification of Category 1. How does this compare in hazard severity to a Category 3 Flammable Liquid?
Category 3 represents an extreme hazard, whereas Category 1 represents a negligible hazard
Both categories have identical physical properties but require different color-coded storage cabinets
Category 1 represents a more severe flammability hazard than Category 3
Category numbers under GHS are arbitrary supplier codes that do not indicate relative hazard levels
What are the three mandatory pieces of information required on a Canadian WHMIS 2015 workplace label?
Manufacturer address, signal word, and transport emergency phone number
Product identifier, safe handling precautions, and a statement indicating that an SDS is available
CAS registry number, NFPA fire diamond rating, and disposal instructions
Bilingual hazard statements, expiry date, and first aid poison control number
Sections you finish are checked off in the contents.