Final answer:
Category A biological agents include toxins and pathogens that pose the highest risk to public and national security. BSL-2 labs handle moderate risk agents and require safety measures. BSL-4 labs work with the most dangerous pathogens, needing the highest level of containment and safety procedures.
Step-by-step explanation:
The category of biological agents that is considered high priority and includes toxins that pose the highest risk to the public and national security is Category A. Characteristics of Category A agents include ease of distribution or transmission, high mortality rate, likelihood of causing social disruption and panic, and the necessity for special public health preparedness. Agents such as Yersinia pestis (plague), anthrax, tularemia, botulinum toxin, several hemorrhagic viruses, and smallpox are examples of Category A biological weapons agents.
Regarding biosafety levels, BSL-2 is appropriate for research with microbes or infectious agents that pose moderate risk to laboratory workers and the community, and are typically indigenous. Laboratories dealing with BSL-2 agents require additional safety measures such as restricted access, personal protective equipment (PPE), and biological safety cabinets for aerosolization procedures.
BSL-4 agents are the most dangerous and include pathogens that are easily transmitted by inhalation and often do not have treatments or vaccinations available, such as Ebola and smallpox viruses.