Who Is Responsible for Hazardous Materials Sent by USPS?

Full responsibility rests with the mailer to comply with Postal Service and non-Postal Service laws and regulations when mailing hazardous material, and anyone who mails or causes to be mailed a nonmailable or improperly packaged hazardous material may face fines or imprisonment (USPS Publication 52, 323.1). The mailer must identify flashpoint, toxicity, corrosive or other hazardous properties before deciding whether an item is mailable.

Labels. Mailers must state whether a shipment contains hazardous materials when generating the label, including labels generated through USPS tools such as Click-N-Ship, USPS APIs or the Merchant Returns Application.

Service Type Codes. Mailers must use a unique hazardous materials Service Type Code (STC) in the Intelligent Mail package barcode or matrix barcode for each domestic outbound and return package containing hazardous materials, except packages bound for APO, FPO and DPO addresses, U.S. territories and possessions, and the Freely Associated States (Puerto Rico is not excepted). The STC must correspond to the product shipped. Combining several extra services, such as signature confirmation and insurance, is prohibited for hazardous materials mailings (Publication 52, 323.2).

Extra Service Codes. Packages containing hazardous materials must carry Extra Service Code 857. Domestic mailers may instead add one of 23 content-specific codes, and ESC 857 may then be omitted if the package record lacks enough extra service fields. USPS recommends the content-specific codes and may make them mandatory later (Publication 52, 323.3).

Shipping files and legacy postage. Mailers using PC Postage or USPS Ship platforms must transmit a Shipping Services File or Shipping Partner Event File with the applicable codes before or when tendering the shipment. Mailers using legacy postage meters or hard-copy postage statements must present hazardous materials shipments at a Postal Service retail or business mail entry unit (Publication 52, 323.4 and 323.5).

Transport outside the mail. Moving hazardous materials before they enter the mail and after they leave USPS custody is subject to DOT regulations (Publication 52, 323.1).

Training. DOT hazmat training for employees who handle shipments is covered in the FAQ on PHMSA hazmat employee training. Proposed changes to the DOT hazardous materials rules are covered in the news post on PHMSA's international harmonization proposal.

The FAQ on mailing drug test specimens covers exempt specimen packaging, and the FAQ on USPS hazardous materials penalties covers civil penalties.