WHMIS and Hazardous Materials

Ontario’s Workplace Hazardous Materials Information System (WHMIS) is the province’s system for telling workers what is in the chemicals they handle and how to stay safe around them. It lives in two places: the Occupational Health and Safety Act (OHSA), which sets the Act-level duty to identify hazardous materials, keep current safety data sheets, and train exposed workers, and the detailed WHMIS regulation (R.R.O. 1990, Reg. 860) made under that Act, which spells out labels, data sheets, education programs, exemptions, and trade-secret claims. This page explains those rules in plain language and links each one to the official source.

These are statutory minimums — a floor, not a ceiling. Sitting over the whole of WHMIS is the OHSA’s general duty to take every reasonable precaution reasonable in the circumstances for the protection of a worker. Meeting the specific WHMIS requirements below is the start of an employer’s obligation, not the end of it; where the source notes draw out a related duty or a wider exposure, that is flagged in the section it belongs to.

What counts as a hazardous product, and where do the rules apply?

A “hazardous product” is any product, mixture, material or substance that has been classified under the federal Hazardous Products Regulations into a category or subcategory of a hazard class set out in Schedule 2 of the Hazardous Products Act. Ontario’s WHMIS regulation designates every hazardous product a hazardous material, which is what brings it inside the rules.

The regulation also defines the supporting pieces an employer deals with day to day: the supplier and workplace labels, the safety data sheet (the document that replaced the old MSDS), and terms such as bulk shipment, container, and fugitive emission — any gas, liquid, solid, vapour, fume, mist, fog or dust that escapes from process or emission-control equipment and that workers may be readily exposed to.

The core duties — labelling, worker education, keeping data sheets — bind employers and workers in relation to hazardous products that are used, stored or handled at a workplace. The scope has real limits:

• Some products are exempt only from the supplier-label, lab-sample and data-sheet rules (ss. 8, 14, 17–18): explosives, cosmetics/devices/drugs/food, pest control products, radioactive nuclear substances, and consumer products (each as defined in its own federal statute).
• Others fall outside the duties entirely: wood and wood products, tobacco, a “manufactured article,” and anything moving under dangerous-goods transport law.
• Hazardous waste gets a lighter touch — an employer must still ensure safe storage and handling through a combination of product identification and worker education.

A common error is assuming a consumer-grade product bought off the shelf is fully exempt. The carve-out is narrower than people think, and worker education still matters.

Some named chemicals also carry their own designated-substance and exposure-limit regulations on top of WHMIS — those are covered on the Sector and Specialized Hazard Regulations page.

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), ss. 1–4.

The statute is the floor, not the ceiling. WHMIS classification and the carve-outs above set the minimum scope of the labelling and data-sheet duties. The OHSA’s overarching duty to take every reasonable precaution still applies to a hazardous material in the workplace even where a narrow WHMIS exemption switches off a specific label, sample, or data-sheet requirement.

What must an employer do when hazardous materials are present in the workplace?

If hazardous materials are present, the Occupational Health and Safety Act puts three core duties on the employer, and all three must be satisfied before the material is used, handled or stored: identify it in the prescribed manner, obtain or prepare a current safety data sheet for it, and train the workers who are or may be exposed.

• Identify it. Every hazardous material has to be identified in the prescribed manner. Nobody is allowed to remove or deface that identification.
• Have a current safety data sheet (SDS). The employer obtains or prepares a current SDS for each hazardous material, as may be prescribed. Both the identifications and the sheets have to be available in English and any other language that is prescribed.
• Train the people exposed. Workers who are or may be exposed to a hazardous material or a hazardous physical agent must receive the prescribed instruction and training, and they are required to participate in it. The employer develops and implements that training in consultation with its joint health and safety committee or health and safety representative, and reviews it with them at least once a year — or more often if a change in circumstances could affect worker health or safety, or if the committee recommends it.

The SDS is not just a binder on a shelf. A copy has to be available in the workplace for workers to examine, furnished to the committee or representative, and made readily available to every worker who may be exposed to that material. An electronic copy satisfies the requirement. The medical officer of health and the local fire department can also obtain copies on request.

Where employers trip up: treating WHMIS as a one-time orientation item, letting data sheets go stale, or skipping the consultation and annual review. If an employer genuinely cannot get a label or SDS after reasonable efforts, the Act requires it to advise a Director in writing rather than pressing ahead without one.

Source: Occupational Health and Safety Act, ss. 37–42.

The statute is the floor, not the ceiling. These Act-level duties are the baseline. The OHSA also imposes a general duty to take every precaution reasonable in the circumstances for the protection of a worker, so satisfying the three identify/SDS/train steps does not, on its own, discharge an employer’s broader obligation to control exposure to a hazardous material.

What are the rules for supplier labels on incoming hazardous products?

Every hazardous product an employer receives from a supplier has to come with a supplier label, whether it is sitting loose or in a container. Confirming that label before the product goes into use is the employer’s responsibility.

A few things follow from that:

• Do not touch the label. While any of the product is still in the container, the employer cannot alter the supplier label. It is left as it came.
• If it goes missing or unreadable, replace it. A label that falls off or becomes illegible has to be swapped for either a supplier label or a workplace label.
• Tiny containers get a break. On a container holding 3 mL or less, the supplier label may be removed if it gets in the way of normal use.
• New hazard data means an update. If the supplier sends significant new information about the product, that updated information must be attached to the relevant labels as soon as reasonably possible.

Where employers trip up: product that shows up without a proper label. An employer that imports and receives a product for its own use, or gets an unpackaged product or a bulk shipment with no supplier label, has to affix one that meets the federal Hazardous Products Regulations requirements. There are also legacy rules for old “WHMIS 1988” labels on stock received on or before August 31, 2018 — where a current supplier label cannot be obtained, it is replaced with a workplace label or a compliant one (the separate workplace-label transition rule is set out below).

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), s. 8.

The statute is the floor, not the ceiling. The supplier-label rules set the minimum identification a hazardous product must carry on arrival. The employer’s wider OHSA duty to ensure the safe storage and handling of that material continues to apply even where a small-container exception or a missing-label situation relaxes the strict labelling requirement.

When must an employer put a workplace label on a hazardous product?

Two situations trigger the employer’s own labelling duty: a hazardous product the workplace produces on site needs a workplace label, and a hazardous product poured from its supplier container into a different container needs a workplace label too.

Products made on site. If the workplace produces a hazardous product, that product (or its container) needs a workplace label. The only escape hatch is that the product is already in a container intended for sale or disposition — meaning it is, or is about to be, carrying the proper label for that purpose. And if significant new data about the product comes to the employer’s attention, the workplace label has to be updated as soon as practicable.

Products decanted. When the employer receives a hazardous product from a supplier and pours it into a different container, that second container needs a workplace label too. Same hazard, new vessel, the employer’s responsibility.

The one real break is for portable containers. No label is required when a worker fills a portable container straight from a properly labelled source and either:

• the worker keeps it under their own control, uses it only during the shift they filled it in, and the contents are clearly identified; or
• all of it is going to be used right away.

Where people trip up: treating that portable-container exception as a blanket pass. It is not. The moment the product sits past the shift, gets passed to a co-worker, or loses its clear identification, the exception evaporates and a proper workplace label is back on the table.

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), ss. 9–10.

The statute is the floor, not the ceiling. The workplace-label rules and the portable-container exception set the minimum labelling for products an employer makes or decants. The OHSA’s general precaution duty still requires the safe handling of those products regardless of whether a short-term portable container qualifies for the labelling exception.

How are old WHMIS 1988 workplace labels swapped out?

When Ontario updated its WHMIS rules, the old-style workplace labels did not earn a permanent pass. An employer must remove an old “WHMIS 1988 workplace label” and affix a current workplace label in its place — but only when all three of the following conditions apply.

The replacement duty applies only when:

• The old WHMIS 1988 label was already on the product or container on or before November 30, 2018.
• That old label would have met the workplace-label requirements under the regulation as those requirements stood immediately before July 1, 2016 (the date the current scheme came into force).
• Today’s regulation still requires a workplace label on that particular product or container.

A “WHMIS 1988 workplace label” is defined simply as a workplace label within the meaning the regulation gave that term before the July 1, 2016 changeover.

In practice, all three conditions must be satisfied before the swap obligation arises. An old label that was never affixed before November 30, 2018, or one that did not comply with the former rules, falls outside this provision. Where all three conditions do line up, the old label is not a permanent fix — it has to come off and be replaced with a current workplace label.

One scope point worth flagging: this provision deals with the workplace label an employer generates in-house, not the supplier label that arrives on the product from the manufacturer.

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), s. 13.

The statute is the floor, not the ceiling. This transition rule sets only the minimum relabelling obligation for legacy workplace labels. It does not relieve an employer of the broader OHSA duty to keep its workers properly informed about a hazardous material that remains in use, whatever the vintage of the label on the container.

How are hazardous products in pipes, vessels and conveyances identified?

Not every hazardous product comes in a neat container that can take a label. When a hazardous product is held or moved through a pipe, a piping system with its valves, a process or reaction vessel, or a conveyance — a tank car, tank truck, ore car, or conveyor belt — the rule shifts: the employer has to keep the product’s use, storage and handling safe through a mix of worker education and some other clear means of identification, such as colour coding, labels, placards, or a similar method. The key is that workers know what they are dealing with, even without a label on the item itself.

A related exception covers when a workplace label is not required at all:

• The product is not in a container; or
• it is in a container, or a form, meant for export; or
• it is in a sale or distribution container that is not labelled yet but will be, in the normal course of business and without undue delay.

In each case there is a catch: a placard that carries the same information a workplace label would must be posted, and it has to be large enough and placed so the details are conspicuous and easy for workers to read.

Where employers trip up: treating “no label needed” as “nothing needed.” The training and the placard still have to be there. A pipe running through a plant with no colour code and no worker who can tell you what is inside is exactly the gap this rule is meant to close.

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), ss. 11–12.

The statute is the floor, not the ceiling. Colour coding, placards and worker education are the minimum identification the regulation will accept for piped and conveyed products. The OHSA’s general duty to ensure safe use, storage and handling of a hazardous material sits over these measures and is not satisfied by signage alone.

What are the label rules and exemptions for laboratory samples?

Laboratory samples get relief from the usual WHMIS supplier and workplace labels, but only if a specific reduced label, or a mix of clear on-site identification and worker training, is in place.

Supplier label exemption. A hazardous product that qualifies as a laboratory sample under the federal Hazardous Products Regulations does not need the standard supplier label. Instead, the supplier must affix a reduced label that gives:

• the chemical or generic name of each ingredient that triggers a hazard classification above its concentration limit (or that makes the mixture hazardous), where the supplier knows it;
• the prescribed bilingual “Hazardous Laboratory Sample” statement; and
• an emergency phone number to reach the safety-data-sheet information.

Workplace label exemptions. No workplace label is needed for a lab sample that is made on site or repackaged out of its supplier container, as long as the employer ties together identification visible to workers and worker education so people can readily find either the safety data sheet or the reduced-label information.

The same exemption covers products made in a lab solely for evaluation, analysis, or testing for research and development purposes, as long as they are never taken out of that lab: the workplace label may be skipped if visible identification plus training lets workers get the SDS or whatever other information is needed to handle the product safely.

Where employers trip up: treating “exempt” as “do nothing.” The exemption is conditional. If the visible identification and the training cannot be shown, the exemption evaporates and a full label is back in play.

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), ss. 14–16.

The statute is the floor, not the ceiling. The reduced lab-sample label and the on-site identification-plus-training substitute are minimum compliance options. They do not displace the employer’s broader OHSA obligation to protect workers handling a hazardous material in a laboratory setting.

What are the supplier and employer safety data sheet duties?

Under WHMIS, every hazardous product is treated as a hazardous material, and that triggers safety data sheet (SDS) duties. The SDS is the detailed information sheet that tells people what is in a product, how it can hurt them, and how to handle it safely. There are two paths, depending on where the product comes from.

Products received from a supplier. If a hazardous product arrives for use, storage, or handling at the workplace, the employer has to obtain the supplier’s SDS for it. The one exception is where the supplier is exempt from providing an SDS under the federal Hazardous Products Regulations. When significant new data about the product comes to the employer’s attention — whether the supplier sends it or the employer finds it another way — the sheet is updated as soon as practicable. The employer can reformat the supplier’s SDS or add extra hazard information of its own, but only if its version has no less content than the supplier’s, and only if the supplier’s SDS is still available at the workplace and the employer’s sheet says so.

Products made on site. If the employer produces a hazardous product at the workplace, it has to prepare its own SDS that meets the federal requirements. The same goes if the employer has labelled a product itself and simply cannot get a supplier SDS for it. Here the update clock is firmer: the SDS must be refreshed as soon as practicable, and no later than 90 days after significant new data reaches the employer. A laboratory sample produced in-house is the one carve-out that needs no SDS.

Where employers trip up: receiving a hazardous product and never chasing down the SDS, or letting an in-house sheet go stale past the 90-day window.

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), ss. 17–18.

The statute is the floor, not the ceiling. The supplier and in-house SDS duties, including the 90-day update window, are the regulation’s minimum information standard. The OHSA’s underlying duty to provide workers with the information they need to handle a hazardous material safely sits above these mechanics.

How must an employer educate and train workers on hazardous products?

If workers handle a hazardous product, or might just be exposed to one on the job, WHMIS puts two duties on the employer: tell them what it knows, and teach them what to do. Informing is not the same as instructing, and both are required.

Inform them. When the employer brings in a hazardous product from a supplier, it has to pass along all the hazard information the supplier gives it — plus anything else it knows, or reasonably ought to know, about using, storing and handling it. If the employer makes a hazardous product itself, the same goes: workers get told everything the employer knows or ought to know about it.

Instruct them. Beyond handing over information, the employer must run a worker education program that covers:

• how to read a label and a safety data sheet, and what the information on each one means;
• safe use, storage, handling and disposal of the product — including when it is moved through pipes, piping systems (valves included), process or reaction vessels, or conveyances such as a tank car, tank truck, ore car, conveyor belt, or anything similar;
• what to do when fugitive emissions are present; and
• what to do in an emergency involving the product.

The program cannot sit on a shelf. It has to be developed and put into use for the actual workplace, tied in with the employer’s other training and prevention programs, and — so far as is reasonably practicable — it has to leave workers genuinely able to use the information to protect themselves.

Where employers trip up: treating a binder of data sheets as “done.” Informing is not instructing. If a worker cannot explain what the label means or what to do in a spill, the second duty has not been met.

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), ss. 6–7.

The statute is the floor, not the ceiling. The WHMIS education program is the minimum instruction the regulation requires for hazardous products. It runs alongside the broader awareness and safety training the OHSA requires; see the Occupational Health and Safety Training Requirements page for the basic awareness and JHSC-certification training that sits beside it.

How must an employer assess hazardous agents it makes in-house?

WHMIS is not only about the labelled drums and bottles an employer buys in. If an operation actually makes a biological or chemical agent and then uses it on site, the employer has a duty to look at that substance and figure out whether it is hazardous. The supplier did not do that homework, because there is no supplier — it came out of the employer’s own process.

The rule is straightforward to state: assess what is produced for in-house use, and treat it as a hazardous material if the assessment says so. The harder part is doing the assessment to the right standard. The regulation requires the assessment to follow Parts 7 and 8 of the federal Hazardous Products Regulations (Canada) — the provisions that govern hazard classification — so a guess or a gut feel will not cut it.

A few things are carved out. The employer does not have to assess:

• wood or a product made of wood;
• tobacco or a tobacco product as the federal Tobacco Act defines it; or
• a “manufactured article.”

Where employers trip up: assuming WHMIS stops at purchased products and never thinking about the by-products, mixtures, intermediates, or biological agents their own work creates. A welding fume, a process residue, a cultured agent — if it is being produced and used, it is on the employer to check. The exemptions are narrow, so they should not be stretched to cover something that only loosely resembles “wood” or a finished article.

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), s. 3.

The statute is the floor, not the ceiling. The in-house assessment duty sets the minimum classification obligation for agents an employer produces. Once an in-house agent is found to be hazardous, the full labelling, SDS, and education duties apply on top of it, as does the OHSA’s general precaution duty.

How does a confidential business information (trade-secret) claim work?

WHMIS forces an employer to disclose what is in a hazardous product so workers can protect themselves, but the law recognizes that some details are genuine trade secrets. An employer may hold back a narrow set of trade-secret details from a label or safety data sheet (SDS) only by filing a formal exemption claim — the employer does not get to decide on its own that something is confidential, and only certain things can ever qualify.

The list of what an employer can ask to withhold is short and specific:

• For a pure material or substance: the chemical name, its CAS registry number or other unique identifier, and the chemical name of any impurity or stabilizer (stabilizing solvents and additives included) that is present in it.
• For an ingredient in a mixture: the ingredient’s chemical name, its CAS registry number or other unique identifier, and the concentration or concentration range at which it is present.
• The name of a toxicological study that could be used to identify the product or an ingredient.
• The product identifier (trade name, brand name, etc.), other identifying information, and anything that could be used to identify a supplier.

Filing a claim does not let an employer go quiet. While the claim is pending the employer must still print on the SDS (and label, if applicable) the date the claim was filed and the registry number assigned under the federal review process — and every other piece of information WHMIS normally requires has to stay on the document. For products an employer makes in its own workplace, it also has to substitute a generic chemical name (or a code name or number for the product identifier) so workers are not left without hazard information.

Where employers trip up: treating a confidentiality claim as permission to strip the SDS bare, or letting the claim and decision details fall off. Once a claim is upheld, the SDS and label must state that an exemption was granted, show the decision date and registry number, and that disclosure obligation runs from the time the claim is finally resolved through the end of the exemption period.

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), ss. 19–23.

The statute is the floor, not the ceiling. The confidential-business-information rules set the minimum disclosure that must remain on a label or SDS even when a trade-secret claim is granted. They do not displace the employer’s wider OHSA duty to keep workers informed, and they are explicitly overridden in a medical emergency (see below).

Must an employer tell a doctor what is in a product, even a trade secret?

Yes. In a medical emergency, if a legally qualified medical practitioner requests product information to diagnose or treat the affected person, the employer must provide it — including confidential business information. The disclosure has to happen because a doctor has requested it for the purpose of diagnosing or treating the person affected. That context matters: the obligation does not arise simply because someone was exposed; it arises when there is a medical emergency and a qualified practitioner asks.

The regulation ties directly back to the Occupational Health and Safety Act, which sets out the same obligation for employers. The WHMIS rule confirms that confidentiality claims an employer would otherwise be entitled to make on a label or safety data sheet do not override a treating professional’s request in that situation. In plain terms: a medical emergency plus a doctor’s request equals a mandatory disclosure — full stop.

Where employers trip up:

• Treating it as a routine information request. The law specifically contemplates a medical emergency. Speed and cooperation matter here, not negotiation.
• Thinking a trade secret claim holds. Confidential business information is explicitly covered by the duty. Claiming secrecy will not protect an employer from the obligation.
• Not being ready to respond fast. The nature of an emergency means there is no time to organize. Employers should know in advance who can reach the supplier or pull complete product data, including off-hours.

The practical preparation is simple: before it is needed, work out who would be called and what information would be pulled if a physician phoned about an exposure. That readiness is the employer’s responsibility.

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), s. 24.

The statute is the floor, not the ceiling. This provision sets the minimum: a confidentiality claim cannot block disclosure to a treating professional in an emergency. The OHSA carries the same obligation, and an employer’s wider duty to cooperate in protecting an injured worker’s health sits above the bare disclosure requirement.

Must an employer disclose where its toxicological data came from?

Yes — an employer that makes a hazardous product in the workplace must, on request, reveal where the toxicological data behind its safety data sheet (SDS) came from. If an employer produces a hazardous product on site and used toxicological data to build the SDS, it has to disclose the source of that data when asked, and do it as quickly as the circumstances allow, not whenever it gets around to it.

A short, specific list of people can ask:

• an inspector;
• any worker at that workplace;
• a member of the joint health and safety committee, if there is one;
• the health and safety representative, if there is one; or
• where there is no committee or representative, someone speaking for the workers.

A couple of points matter in practice. First, the duty is about the source of the data, not handing over a competitor’s secret recipe. The disclosure is tied to the trade-secret protections in subsection 40(6) of the Occupational Health and Safety Act, so the obligation runs subject to those limits. Second, it is a producer’s duty: it bites when the employer makes the hazardous product, not merely when it buys and uses someone else’s.

Where people trip up is treating the SDS as the finish line. It is not. If a worker or the committee asks the employer to back up the numbers, stalling or shrugging is a compliance problem. The practical step is to keep a record of data sources so a request can be answered promptly.

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), s. 25.

The statute is the floor, not the ceiling. This is the minimum disclosure a producing employer owes about the basis for its SDS, bounded by the s. 40(6) trade-secret protections. It does not limit the wider OHSA right of workers and the committee to the information they need to assess a hazardous material in their workplace.

Is there a grace period for storing products while chasing labels and SDS?

Yes, but a narrow one. An employer may store a hazardous product without a WHMIS label, safety data sheet, or worker education program only while it is actively trying to get the missing label and SDS. WHMIS normally requires a proper label, an SDS, and worker education before a hazardous product is put to use; the regulation carves out a break that applies only to products in storage, and only while the employer is genuinely working to close the gap.

There are two versions of the same rule:

• Supplier products. When a hazardous product arrives from a supplier without a label or without an SDS, the employer may store it without those documents and without running a worker education program — but only for as long as it is actively pursuing a supplier label and a supplier SDS.
• Products made in-house. When an employer produces a hazardous product on-site, it may store that product without a label or other identifying mark, without an SDS, and without worker education — but only while it is actively gathering the information needed to prepare a workplace label and an SDS.

The word doing the heavy lifting is “actively.” The moment that effort stops, the exemption stops. This is a stopgap for products waiting in storage, not a standing licence to skip WHMIS obligations.

Where employers trip up: treating the exemption as open-ended, or assuming it continues after they have stopped pursuing the missing label or SDS. The regulation is clear that the exemption exists only for as long as the chase is ongoing.

Source: Workplace Hazardous Materials Information System (WHMIS) (R.R.O. 1990, Reg. 860), s. 5.

The statute is the floor, not the ceiling. The interim-storage exemption is a minimum, time-limited stopgap. It does not relieve the employer of the OHSA’s general duty to keep a stored hazardous material safe, and it lapses the moment the active pursuit of the label and SDS ends.

---

This page is general information about Ontario occupational health and safety law, not legal advice. The WHMIS exemptions, transition rules, and trade-secret claims above are narrow and conditional, and the federal Hazardous Products Regulations they depend on change over time — so confirm the current requirements at the official sources and obtain advice before relying on any exemption or skipping a label, data sheet, or training step.