In international commerce, hazardous materials are referred to as "dangerous goods."
Almost all dangerous materials are prohibited in international mail. The only mailable dangerous materials are certain infectious substances, excepted quantities of radioactive material that are allowed in domestic mail, certain magnetized materials, and certain lithium and lithium-ion batteries. Exhibit 621.1 provides a summary of the types of dangerous materials that are eligible for mailing in international mail.
The few types of dangerous materials that are generally permitted in international mail may be further restricted by the mailing limitations imposed by an individual country. Because individual countries have unique prohibitions and restrictions, it is always necessary to consult the ICL in the IMM to be certain that an otherwise mailable dangerous material is acceptable for shipment to a specific country.
Except as otherwise specified, rigid outer packaging must be used for shipments containing dangerous goods following the instructions in 339.4.
The nine classes of hazardous materials listed in 331 also apply to dangerous goods shipped in international commerce.
The non-Postal Service regulations that govern the air shipment of dangerous goods in international commerce are specified in the Technical Instructions for the Safe Transport of Dangerous Goods by Air of the International Civil Aviation Organization (ICAO). In Title 49 Code of Federal Regulations (CFR), Department of Transportation (DOT) recognizes ICAO requirements for the air transportation of dangerous materials. However, 49 CFR gives DOT the authority to regulate only the domestic transportation of dangerous materials. Generally, most air carriers follow the Dangerous Goods Regulations of the International Air Transport Association (IATA), which are slightly more restrictive than ICAO rules.
The Limited Quantity category is unique within domestic commerce and is not recognized in international commerce. Dangerous materials under this classification that are mailable in domestic mail are typically prohibited in international mail.
Mailers shipping dangerous goods internationally, including to APO/FPO/DPO and U.S. Possessions, Territories, and Freely Associated States destinations utilizing PC Postage or USPS Ship platforms, must include Extra Service Code (ESC) 857 and incorporate the applicable content- specific ESC listed in Appendix G and Publication 199. A Shipping Services File (SSF) using Version 1.7 or higher, or Shipping Partner Event File (SPEF) using Version 5.0 or higher, must be transmitted to the Postal Service before, or concurrent with, tendering dangerous-goods shipments.
