U.S. moves to recognize Canada's 2024 TDG amendments for cross-border dangerous goods
A PHMSA proposal published October 27 would update the edition of Canada's TDG Regulations the U.S. accepts. Comments close December 28.
Canadian carriers hauling dangerous goods into the U.S. could soon work from a newer TDG rulebook on both sides of the border.
The U.S. Pipeline and Hazardous Materials Safety Administration (PHMSA) published a proposed rule in the Federal Register on October 27. Known as HM-215S, it is the agency's regular update to line up the U.S. Hazardous Materials Regulations (HMR) with international standards.
The Canadian piece
PHMSA proposes to replace the edition of Transport Canada's Transportation of Dangerous Goods Regulations that the HMR currently references. The new reference would be the TDG Regulations "as last amended on October 25, 2024."
That reference appears in 18 sections of the U.S. rules. They include 49 CFR 171.12, the section on North American shipments, plus sections on marking, labelling, placarding, emergency response information and cylinders.
PHMSA's earlier HM-215R proposal, published February 10, 2026, had proposed adopting the 2023 edition of the TDG Regulations. HM-215S would move the reference up to the 2024 amendments.
The wider update
The proposal also lines the HMR up with:
- the 24th revised edition of the UN Model Regulations
- the 2027-28 edition of the ICAO Technical Instructions for air
- Amendment 43-26 of the IMDG Code for marine, which becomes mandatory on January 1, 2027
Changes cover proper shipping names, hazard classes, packing groups, special provisions, packaging authorizations, air quantity limits and vessel stowage.
One change touches large battery shipments. PHMSA proposes splitting UN3536, today used for lithium batteries installed in a cargo transport unit, into three entries: lithium ion (UN3536), lithium metal (UN3563) and sodium ion (UN3564). The agency pointed to a 2024 fire near Baker, California, where responders at an overturned truck could not tell which battery chemistry was on board.
What happens next
This is a proposal, not a final rule. Nothing changes for drivers or shippers today.
Comments are due December 28, 2026, under docket PHMSA-2025-0048.