Which UN number is associated with Biological Substances, Category B shipments?

• A. UN 2814
• B. UN 3373
• C. UN 2900
• D. UN 1993

Answer: (B)

Biological Substances, Category B are infectious materials that aren’t as dangerous as Category A items. The UN number assigned to these Category B substances is 3373, and this designation guides the packaging, labeling, and handling requirements for shipping to reflect the lower risk level compared with Category A. In contrast, Category A (more hazardous) uses UN 2814 for substances affecting humans, and other numbers in the list correspond to different hazards—UN 2900 for infectious substances affecting animals, and UN 1993 for flammable liquids. So, for Biological Substances, Category B shipments, the UN number is 3373.