A hazardous material (referred to as a "dangerous good" in international
commerce) is any article or substance having a clear potential for causing
harm to the mail or to persons or property involved in moving the mail.
The Department of Transportation (DOT) regulates all surface and air
carriage of hazardous materials within the United States via any means
of transportation. DOT regulations on hazardous materials are codified in
Title 49, Code of Federal Regulations (49 CFR), parts 100-185.
Mailers are reminded that it is a federal crime, punishable by fines and
imprisonment, to place in the mails any "natural or artificial articles,
compositions, or material which may kill or injure another, or injure the mails
or other property ...." (18 U.S.C. 1716(a)). This statute allows the Postal
Service to permit the mailing of some injurious articles under regulations
prescribing conditions of preparation and packaging (18 U.S.C. 1716(b)).
For more specific information, see DMM C020 and C023 and Publication 52,
Hazardous, Restricted, and Perishable Mail.