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DMM Reference 601.10.17.4

Infectious substance means a material known or reasonably expected to contain a pathogen. A pathogen is a microorganism that can cause disease in humans or animals. Examples of pathogens include bacteria, viruses, fungi, and other infectious agents. An infectious substance must be assigned to one of the following two packaging categories:

Proper Shipping Name and ID Number


  • International Mail: Mailable when they meet the definition in 346.12a2 and IMM 135 when written approval has been granted by the manager of Product Classification. Category B infectious substances may be sent with registered First-Class Package International Service or the Priority Mail International Small Flat Rate Priced Boxes using Registered Mail service.
  • Domestic Mail: Mailable only when they are intended for medical or veterinary use, research, or laboratory certification related to the public health, and when such materials are properly prepared for mailing to withstand shocks, pressure changes, and other conditions related to ordinary handling in transit. Unless otherwise noted, all mailable Division 6.2 materials must meet the mail preparation requirements for air transportation and sent via Priority Mail Express, Priority Mail, First-Class Mail, or First-Class Package Service.

Required Packaging

Primary Receptacle (Container)
Cushioning and Absorbent Material
Secondary Container
Outer Shipping Container

As required by 49 CFR 173.199:

International Mail

Note: Countries distinguish between infectious and noninfectious (nonregulated) biological substances and may prohibit one or the other or both. See “Prohibitions” in the Individual Country Listings.