The legal framework

Dangerous goods rules come in layers. At the top sit international recommendations written by the United Nations. Below them are the international rules for air and sea transport, and the national law of each country. Below those are provincial laws, industry standards for containers and the company procedures that put everything into practice. To work safely with dangerous goods you do not need to read every page, but you do need to know which document governs your shipment and where to look things up.

The United Nations Model Regulations

The United Nations Economic and Social Council has a Sub-Committee of Experts on the Transport of Dangerous Goods. Every two years it publishes a revised edition of the Recommendations on the Transport of Dangerous Goods, Model Regulations, nicknamed the Orange Book after its cover. The Model Regulations define the nine classes, the numbering system of four-digit UN numbers, the list of dangerous goods with their proper shipping names, the packing groups, the packaging performance tests and the design of labels and placards. They are not law in themselves. Countries and international bodies adopt them, sometimes with variations, into binding rules. A companion volume, the Manual of Tests and Criteria, explains the laboratory tests used to classify products.

Because almost every country builds on the same model, a drum of corrosive liquid classified and marked in Montreal, Chicago, Rotterdam or Singapore carries the same UN number, class label and packaging code. That shared language is what makes international trade in dangerous goods possible.

International rules for air and sea

Air transport is governed internationally by the International Civil Aviation Organization's Technical Instructions for the Safe Transport of Dangerous Goods by Air, usually called the ICAO Technical Instructions, issued in two-year editions. Airlines also follow the International Air Transport Association's Dangerous Goods Regulations, a manual that incorporates the ICAO rules and adds airline-specific restrictions; it is updated every year. Air rules are the strictest of all modes because of pressure changes, temperature extremes and the impossibility of stopping to deal with a leak at altitude. Many products allowed by road are limited or forbidden by air, especially on passenger aircraft.

Sea transport is governed by the International Maritime Dangerous Goods Code, the IMDG Code, published by the International Maritime Organization and updated every two years. It adds rules about stowage and segregation on ships and about marine pollutants, which are products that harm aquatic life. Amendment 42-24 of the IMDG Code became mandatory on 1 January 2026.

Road and rail rules in Europe are found in agreements known as ADR (road) and RID (rail). North America does not use them, but you may see the terms on documents for imported goods.

National law

In Canada the Transportation of Dangerous Goods Act, 1992 gives the federal government power to regulate dangerous goods transport, and the Transportation of Dangerous Goods Regulations set out the details. Transport Canada writes and enforces the regulations through its Transportation of Dangerous Goods Directorate, and runs CANUTEC, the Canadian Transport Emergency Centre, which gives 24-hour advice to responders. The Act gives inspectors the power to enter premises, examine dangerous goods and documents, take samples, and order that unsafe shipments be stopped or corrected. It also sets out offences. On summary conviction, a first offence can bring a fine of up to $50,000 and each later offence up to $100,000; on indictment, a person can be imprisoned for up to two years, and each day an offence continues can be treated as a separate offence.

The dangerous goods list is Schedule 1. For each entry it gives the UN number, the shipping name and description, the class, the packing group, any special provisions, the limited quantity and excepted quantity amounts, the quantity above which an emergency response assistance plan is required, and quantity limits for passenger carrying vehicles. Schedule 2 contains the special provisions, numbered rules that modify the general requirements for particular entries. Lesson 5 shows how to read Schedule 1.

Most of Part 9 is short, because so much of the work is done in Parts 1 to 8. But Part 9 contains one rule that matters a great deal in practice: dangerous goods may be transported by road in Canada in compliance with the US Hazardous Materials Regulations, subject to conditions such as Canadian requirements for emergency response assistance plans, reporting and training, and documents in English or French. Part 10 has a similar rule for rail. Parts 11 and 12 allow the IMDG Code and the ICAO Technical Instructions to be used for marine and air transport. Amendments published in mid-2026 also recognized US special permits for the first leg of a cross-border shipment, as long as the permit number appears on the shipping document, and accepted US inhalation hazard labels and placards.

Provincial, territorial and local rules

Dangerous goods transport that stays entirely within one province is technically provincial. Every province and territory has adopted the federal TDG Regulations, in whole or in large part, through its own legislation, so in practice the same rules apply across the country. Provinces enforce them on their roads through highway safety officers and police, and provincial highway traffic acts add rules about routes, tunnels and bridges where dangerous goods are restricted. Municipalities can set dangerous goods routes through their bylaws. Workplace rules such as WHMIS and the occupational health and safety acts apply to the people who handle the goods.

Other federal laws touch dangerous goods too. The Explosives Act and its regulations govern explosives, the Nuclear Safety and Control Act and the Packaging and Transport of Nuclear Substances Regulations, 2015 add requirements for radioactive materials, and environmental laws cover hazardous waste movements, including the Cross-border Movement of Hazardous Waste and Hazardous Recyclable Material Regulations. Drivers of commercial vehicles must also meet provincial licensing and hours-of-service rules.

Standards for containers

The TDG Regulations incorporate national standards by reference. These set the design, testing and marking requirements for small packagings, intermediate bulk containers, cylinders, highway tanks and rail tank cars. Examples include CAN/CGSB-43.150 for the selection and use of small means of containment and intermediate bulk containers, which in 2026 replaced two older documents, and CSA B339 and B340 for cylinders. The regulations also accept many UN-standard packagings made in other countries. Lesson 6 explains how to read the marks that show a container meets a standard.

Finding the current rules

The official consolidated TDG Regulations are free on the Justice Laws website, and Transport Canada publishes guidance, bulletins and an online TDG regulations search tool. Amendments appear in the Canada Gazette, Part II. Because the list of dangerous goods and many special provisions change with each amendment, a printed copy from a few years ago can mislead. Check the date of any reference you use.

# Which rule set governs a shipment? A simplified decision helper (not a substitute for the rules).
def rule_set(mode, origin, destination):
    if mode == "air":
        return "ICAO Technical Instructions (and IATA DGR for airlines)"
    if mode == "sea":
        return "IMDG Code (plus national port rules)"
    if {origin, destination} <= {"Canada"}:
        return "TDG Regulations"
    if {origin, destination} <= {"USA"}:
        return "49 CFR (HMR)"
    if {origin, destination} == {"Canada", "USA"}:
        return "TDG in Canada and 49 CFR in the US; either set is accepted for road and rail, with conditions"
    return "Check national rules of every country on the route"

for trip in [("road", "Canada", "Canada"), ("rail", "USA", "USA"),
             ("road", "Canada", "USA"), ("air", "Canada", "USA"), ("sea", "USA", "Mexico")]:
    print(f"{trip[0]:>4} {trip[1]} to {trip[2]}: {rule_set(*trip)}")

road Canada to Canada: TDG Regulations
rail USA to USA: 49 CFR (HMR)
road Canada to USA: TDG in Canada and 49 CFR in the US; either set is accepted for road and rail, with conditions
 air Canada to USA: ICAO Technical Instructions (and IATA DGR for airlines)
 sea USA to Mexico: IMDG Code (plus national port rules)

The helper above is deliberately simple, but it reflects how professionals think: identify the mode first, then the countries involved, then find the governing document. Real shipments add details, such as an air shipment that starts with a truck to the airport, which must meet both the road rules and the air rules for its whole journey.

Reading regulatory text

Regulations are written precisely, and small words matter. Shall and must create obligations; may gives a choice. A list joined by and requires every item, while or requires only one. Definitions at the start of the regulations often give ordinary words a narrower meaning, so a term such as handling, offering for transport or bulk may not mean what it means in everyday speech. When a section seems to say something surprising, read the definitions and any exceptions that follow it before acting.