PHMSA Proposes Aligning United States Hazardous Materials Rules With Global Standards

The Pipeline and Hazardous Materials Safety Administration (PHMSA), part of the U.S. Department of Transportation, proposed on 27 October 2026 to update the Hazardous Materials Regulations so they track the newest international rules on shipping names, hazard classes, packing groups and vessel stowage. The notice of proposed rulemaking, filed as Docket No. PHMSA–2025–0048 (HM–215S) under RIN 2137–AF75, appears in the Federal Register of that date. Interested parties have until 28 December 2026 to file comments.

The proposal covers 49 CFR parts 171, 172, 173, 175, 176, 178 and 180 — the whole of the Hazardous Materials Regulations (HMR). Under the Federal Hazardous Materials Transportation Law (49 U.S.C. 5120), the Secretary of Transportation must keep domestic rules generally consistent with the latest international regulations and standards unless they are unnecessary or unsafe, or unless a more stringent safety standard is in the public interest. The changes form part of PHMSA’s biennial harmonization cycle, whose underlying international editions are published by, or take effect on, 1 January 2027. PHMSA says the amendments would preserve current safety levels while cutting delays and interruptions in hazardous materials traffic.

The international editions PHMSA would adopt

The rulemaking would revise the list of materials incorporated by reference in 49 CFR 171.7 to add or update:

• The 2027–28 edition of the International Civil Aviation Organization (ICAO) Technical Instructions.
• The 2026 edition of the International Maritime Dangerous Goods (IMDG) Code, incorporating Amendment 43–26, plus updated SOLAS Chapter II–2 fire-protection and dangerous-goods carriage regulations.
• The 2024 updates to Transport Canada’s Transportation of Dangerous Goods Regulations.
• The 24th revised edition (2025) of the United Nations Model Regulations.
• A set of International Organization for Standardization (ISO) standards on gas cylinders, valves and testing, including ISO 535:2023, ISO 1496–3:2019, ISO 4706:2023, ISO 10297:2024, ISO 18119 and ISO 22434:2022.

What PHMSA declines to adopt

PHMSA explicitly rejected several elements of the 24th revised UN Model Regulations, arguing they offered no measurable safety gain or would disrupt established U.S. practice. Among them:

• Revised definitions of “cylinder”, “bundle of cylinders”, “tube” and “usable water capacity”.
• The updated UNMR indicative list of Category A infectious substances, and new exceptions for contaminated medical devices.
• Special packing provision PP99 for environmentally hazardous paints, and new rules for UN fiber-reinforced plastic portable tanks.
• Replacing “net explosive weight” with “net explosive mass”.
• Provisions on recycled plastics in intermediate bulk containers, and ISO 11515:2022, which PHMSA said contains a typographical error on liner-thickness thresholds.

Shipping names, packing groups and stowage

The most granular changes fall on the Hazardous Materials Table in 49 CFR 172.101:

• UN2857 and UN3358 would be renamed “Refrigerating machines or heating machines”, supported by a new Special Provision 75 covering equipment that both heats and cools, such as heat pumps.
• The Organic Peroxide Table would replace the single artemisinin entry with five names — Arteether, Artemether, Artemisinin, Artesunate and Dihydroartemisinin, each including stereoisomers — classified as UN3106 with packing method OP7.
• UN2862, Vanadium pentoxide, would gain a new packing group II entry, and stowage code 40 (“stow clear of living quarters”) would be removed.
• UN2956, Musk xylene, would lose its limited-quantity authorization, aligning the HMR with the IMDG Code.
• UN2225, Benzene sulfonyl chloride, would be assigned stowage codes 53 and 58, requiring separation from alkaline compounds and cyanides respectively.

Air and vessel provisions

For air transport, PHMSA would cap power banks at two per passenger, bar their recharging aboard aircraft and recommend against using them to charge other devices, mirroring Addendum No. 1 to the 2025–26 ICAO Technical Instructions. Sodium ion batteries would be added wherever lithium batteries are covered. Explosives in Compatibility Group G could no longer be stowed with Groups C, D or E, and would have to sit at least 2 m (6.5 ft) apart.

For vessels, 49 CFR 176.905 would be rewritten so shippers must assess a vehicle’s condition before offering it for water transport, responding to National Transportation Safety Board recommendation M–21–014 issued after the fire aboard the Höegh Xiamen. Cargo transport units holding lithium ion or sodium ion batteries would also need the corresponding shipping description.

Cost savings and the comment process

PHMSA estimates net annualized cost savings of about $56,000 at a 3 percent discount rate and $49,000 at 7 percent, and does not treat the rule as a significant regulatory action under Executive Order 12866. The agency also expects small effects on paperwork: four domestic manufacturers would each spend 43 hours on tank redesigns in 2028 and four designated approval authorities four hours per review, for 188 hours across eight responses, while explosives approvals would see one fewer respondent and 4.75 fewer burden hours.

For shippers, carriers, packaging makers and exporters, the value of the package lies less in any single entry than in the alignment itself: a single set of descriptions and stowage rules for goods moving into, out of and through the United States reduces the cost of running parallel compliance systems. PHMSA will weigh late comments where it can, but the record closes on 28 December 2026, ahead of a final rule that operators will need in place before the 2027 editions take effect.

Source: Federal Register, Vol. 91, No. 206, 27 October 2026, Proposed Rules, p. 67720 (official reference: 2026-21922).