IATA Dangerous Goods Shipping Test 2026 – Complete Practice Exam

The DOT flow chart splits infectious substances into two main risk levels based on the form and risk of the material. Category A covers substances that meet criteria for high risk (typically cultures or materials that could cause severe disease) and require UN 2814 packaging. Category B covers infectious substances that do not meet Category A criteria, usually clinical or diagnostic specimens that may contain infectious agents but are not high-risk forms, and are shipped under UN 3373 packaging.

TB sputum is a clinical or diagnostic specimen that may contain Mycobacterium tuberculosis but isn’t a cultured/high-risk material. On the DOT flow chart, such specimens are placed in Category B, not Category A. That’s why TB sputum is classified as Category B. It’s not exempt, and the flow chart does cover TB sputum, just not under the higher-risk Category A.