Dangerous Goods 101: What Ontario Shippers Must Declare
Canada's TDG rules in plain language: the nine classes, what consignors must declare and document, and why your carrier needs to know before booking.
Plenty of dangerous goods don’t look dangerous. Aerosol cans, lithium batteries, paints and solvents, pool chemicals, some cleaning products, small propane cylinders — everyday commercial items that ship between Ontario businesses constantly, and many of them are regulated when they travel by road. In Canada, the framework is the federal Transportation of Dangerous Goods (TDG) Act and its regulations, administered by Transport Canada, and it puts the first and most important duty on the shipper: know what you’re shipping, and declare it.
This post is a plain-language orientation for shippers — what counts as dangerous goods, what the consignor is responsible for, and why the conversation with your carrier has to happen before booking. It is educational only, not legal or regulatory advice: TDG requirements are detailed and change over time, and Transport Canada is the authority to verify against.
What counts as dangerous goods
Dangerous goods are products and substances capable of posing a risk to health, safety, property or the environment in transport, and the TDG system sorts them into nine classes. In rough plain-language terms:
- Explosives — from blasting products down to some cartridges and signal flares.
- Gases — compressed, liquefied or dissolved: propane, aerosols, refrigerant cylinders.
- Flammable liquids — fuels, many paints, thinners, solvents, some adhesives.
- Flammable solids and related substances that ignite or react readily.
- Oxidizers and organic peroxides — including some pool and sanitizing chemicals.
- Toxic and infectious substances — certain pesticides, lab and medical materials.
- Radioactive material — specialized industrial and medical sources.
- Corrosives — acids, some battery electrolytes, aggressive cleaners.
- Miscellaneous — the catch-all that includes lithium batteries, among others.
The pattern worth noticing: classes 2, 3, 8 and 9 are full of ordinary commercial products. The question “do we ship dangerous goods?” can’t be answered by intuition — it’s answered by checking your products’ safety data sheets and classifications. If the term “consignor” is new, our freight terms glossary covers it and the rest of the paperwork vocabulary — in TDG contexts it means the party offering the goods for transport, which is usually the shipper.
The consignor’s duties: classify, document, mark, contain
The TDG framework assigns the shipper-side duties to the consignor, and they come down to four things:
- Classification. Determine whether the product is regulated and, if so, its class, shipping name and identification number. This information comes from the product’s manufacturer and safety data sheet, not guesswork.
- Documentation. Regulated shipments travel with a shipping document describing the dangerous goods so the carrier — and any emergency responder — knows exactly what’s aboard.
- Safety marks. Packages carry the required labels, and vehicles display placards when the rules call for them, so the hazard is visible from the outside.
- Means of containment. Dangerous goods go in packaging designed and certified for the purpose — the standards for containers are part of the framework, not a shipper preference.
There’s a fifth duty wrapped around the other four: training. People who handle, offer for transport or transport dangerous goods must be trained and certified for the tasks they perform. If your staff prepare regulated shipments, that requirement reaches into your building.
For the compressed version of the shipper’s question — “is this TDG, and do I have to declare it?” — our answer page on what TDG is and whether you must declare is the quick reference.
Why undeclared dangerous goods are a serious problem
Every protection in the TDG system depends on the declaration. The driver’s handling, the carrier’s acceptance decision, the emergency response if something goes wrong — all of it assumes the paperwork tells the truth about what’s in the truck. An undeclared aerosol case or battery shipment removes those protections silently: nobody knows to keep it away from heat, nobody knows what they’re looking at in an incident, and responders arrive without the information the shipping document exists to give them.
The consequences run in layers. There’s the safety risk itself. There’s regulatory exposure — non-compliance with TDG requirements is an offence that can bring significant penalties. And there’s the commercial layer: undeclared DG can void the assumptions your carrier accepted the freight under, complicate insurance, and end the carrier relationship. Carriers treat this seriously enough that it features in why carriers refuse some loads — a refusal at booking is the system working.
Exemptions exist — but they’re determinations, not assumptions
The TDG framework isn’t all-or-nothing. It contains exemptions and reduced requirements — limited-quantity provisions for small consignments are the best-known example — that recognize a case of consumer-packaged aerosols is not a tanker of the same substance. Under the right conditions, some requirements relax.
The caution is that exemptions have precise conditions: quantity thresholds, packaging requirements, marking requirements. Whether one applies to your shipment is a determination someone qualified should make against the current regulations, and Transport Canada’s published guidance is where to verify. What never relaxes is honesty with your carrier: even when an exemption applies, the carrier should know what’s in the freight it’s accepting.
Talk to your carrier before you book — not at the dock
Certified dangerous goods handling is the carrier’s side of the equation, and it’s a confirmation each carrier has to make for itself: DG work requires trained personnel and the right procedures, and not every carrier offers it. That makes the pre-booking conversation the whole game. Tell the carrier exactly what’s shipping — product, class, quantities — and let them tell you whether they can take it. What you want to hear is a clear yes with the details handled, or a clear no with a referral; what you don’t want is a shrug.
The good news for most Ontario shippers: the large majority of B2B freight isn’t regulated at all. Parts, equipment, documents, dry goods, materials — ordinary freight moves on ordinary service, and a same-day direct run across the GTA needs nothing more than accurate weights, dimensions and addresses. TDG diligence isn’t about treating every shipment as hazardous; it’s about knowing which few are, and saying so.
The takeaway
Under Canada’s TDG framework, the shipper’s duty is knowledge and declaration: know your products’ classifications, document and mark regulated shipments properly, train the people who prepare them, and tell your carrier before booking. Verify anything load-bearing with Transport Canada, because the regulations are detailed and current rules always outrank summaries like this one.
If you have general freight moving in the GTA, Golden Horseshoe or Southern Ontario — and a straight answer about anything unusual in it — request a quote and a real person at Sonic Transport will sort out the right way to run it.
Frequently asked questions
Are lithium batteries dangerous goods?
Generally yes — lithium batteries are regulated as dangerous goods, whether shipped on their own or inside equipment, though the rules vary with battery type, size and packaging, and some consignments qualify for reduced requirements. If your shipment includes lithium batteries, raise it with your carrier and verify the current requirements with Transport Canada before booking.
What happens if I ship dangerous goods without declaring them?
Undeclared dangerous goods put drivers, other road users and emergency responders at risk, because nobody handling the shipment knows what they're dealing with. It's also an offence under the TDG framework that can carry serious penalties for the shipper, and it can void the assumptions your carrier and insurers relied on. Declaration is not optional paperwork — it's the core duty.
Do small quantities of regulated products still need to be declared?
Sometimes not in full — the TDG framework includes exemptions, such as limited-quantity provisions, that relax requirements for small consignments meeting strict conditions. But whether an exemption applies is a determination to make properly, not assume. Confirm the current rules with Transport Canada and tell your carrier what's in the shipment either way.