MOST riot control agents are considered to be in DOT hazard class:

• A. 2.3
• B. 4.1
• C. 6.9
• D. 6.1

Answer: (D)

Riot control agents pose a health hazard to people, not primarily a flammability or reactivity hazard. In DOT terms, the main concern is toxicity to humans from exposure, which is captured by Class 6, Toxic Substances. The subcategory most applicable to these agents is the toxic substances category, so they’re classified as 6.1. Although some riot control agents can release toxic vapors, their primary hazard is the toxic/irritant effect on the body, not being a “poisonous gas” by itself (which would be Class 2.3). Flammable solids fall under 4.1, which doesn’t describe these agents, and other toxic designations don’t fit their typical hazard profile. So, the best match for how they’re treated in transport is Class 6.1 Toxic Substances.