Category B infectious substances (UN3373)
For Category B infectious substances (UN3373), carrier is USPS; restriction type is restricted; scope is domestic mail and limited international mail; conditions is Mailable only when intended for medical, veterinary, research, or public health lab use; must be properly prepared; domestic mailing requires Priority Mail or Priority Mail Express; international requires written approval from director Product Classification, recorded from its source on 2026-08-04.
- Item category
- Category B infectious substances (UN3373) unconfirmed
- Carrier
- USPS our reading
- Restriction type
- restricted our reading
- Scope
- domestic mail and limited international mail our reading
- Conditions
- Mailable only when intended for medical, veterinary, research, or public health lab use; must be properly prepared; domestic mailing requires Priority Mail or Priority Mail Express; international requires written approval from director Product Classification unconfirmed
Values marked unconfirmed are shown, but we could not tie them to the quote below: Conditions, Item category. Read the quote and judge them yourself.
Values marked our reading are our classification of what the source says — the source does not print them in those words. The quote below is the evidence for each one; judge it yourself.
What the source says
Domestic Mail: Infectious substances are mailable only when intended for medical or veterinary use, research, or laboratory certification related to public health, and must be properly prepared to withstand shocks, pressure changes, and other conditions incident to ordinary handling in transit.
— pe.usps.com, retrieved 2026-08-04
Source
- pe.usps.comhttps://pe.usps.com/text/pub52/pub52c3_025.htm