The Postal Service accepts for mailing a very small number of certain
potentially hazardous materials that are not outwardly or of their own force
dangerous or injurious to life, health, or property. Generally, this is limited to
ORM-D materials that are hazardous materials presenting the lowest level of
risk during transportation. The conditions of preparation and packaging under
which such materials are accepted are explained in the DMM and in
Publication 52. Conditions applicable to mailings of hazardous materials to
foreign addresses are explained in the IMM.
Postal standards for hazardous materials closely adhere to 49 CFR and very
often include additional restrictions and prohibitions. Generally, the
acceptability of chemicals and other types of hazardous materials for mailing
depends on container fluid/vapor capacities, the ability of the complete
package to contain the product, and the method of absorbing and containing
the product in case the primary container accidentally leaks. To determine
mailability of a specific product, a mailer must submit a material safety data
sheet (MSDS) and the following information to the RCSC serving the mailer's
• Name of material, hazard class, and assigned UN or NA identification
• Chemical composition by percentage of ingredient.
• Toxic properties.
• Effect of material when it is inhaled or swallowed or when it comes in
contact with eyes or skin.
• Special precautions necessary to permit handling without harm to
USPS employees or damage to property or other mail.
• Explanation of warning labels and shipping papers required by state or
• Proposed packaging method, including addressing and required
To be acceptable for mailing, hazardous materials must be packaged as
required by DMM C023 and Publication 52.