UNunnums
3373

UN 3373Biological substance, Category B

Division 6.2

Infectious substances

Summary

UN 3373 is the UN number for biological substance, Category B. It is classed in Division 6.2 (infectious substances) of Class 6 for transport. Emergency responders use ERG guide 158.

Emergency response

The Emergency Response Guidebook (ERG2024) guide for this number:

  • Guide158Biological substance, category B

From the 2024 Emergency Response Guidebook (ERG2024), published by U.S. Department of Transportation, PHMSA. Read the full guide in the ERG or on CAMEO Chemicals.

Identification

UN number
UN 3373
Name
Biological substance, Category B
Hazard class
Class 6: Toxic and infectious substances
Division
6.2: Infectious substances
What the class covers
Substances known or reasonably expected to contain pathogens.

U.S. Hazardous Materials Table

The entry for this number in 49 CFR 172.101.

  • UN3373Biological substance, Category B

    Special provisions: A82

    Class
    6.2
    Packing group
    None
    Labels
    None

From the eCFR edition of 49 CFR 172.101 dated 2026-10-05 (section last amended 2026-09-08). The eCFR is an editorial compilation, not the official legal edition. Read the current table.

About Class 6

Class 6 covers poisons and infectious material. Division 6.1 is toxic substances that harm people if swallowed, inhaled or absorbed through the skin; 6.2 is infectious substances such as cultures and medical waste.

See all Class 6 UN numbers

Check the official sources

For emergency response, packaging and quantity limits, use these: