Which statement best describes Category A infectious substances?

• A. They are infectious substances capable of causing death or severe disease in humans or animals.
• B. They are infectious substances not capable of causing serious disease.
• C. They are exempt from labeling.
• D. They are liquids only.

Answer: (A)

Category A infectious substances are the most dangerous in transport because they are capable of causing death or severe disease in humans or animals. That potential for severe outcome is exactly why their handling, packaging, labeling, and documentation are among the most stringent in shipping dangerous goods. The emphasis is on the severity of illness that could result from exposure, which justifies rigorous containment and clear identification to prevent any release or misinterpretation during transport. Substances in this category require proper shipping names, UN numbers, and packaging that prevents leakage, along with thorough documentation and special handling procedures.

This description remains accurate regardless of whether the material is a liquid, solid, or powder—its hazard level is defined by the potential to cause serious disease, not by its physical state. In contrast, statements implying they’re non-serious, exempt from labeling, or restricted to liquids do not fit the true nature of Category A materials. Category B exists for infectious substances that pose a lesser risk and follow different, typically less stringent, packaging and labeling requirements.