Which biosafety level would be appropriate for well-characterized agents that do not cause disease in healthy humans?

The appropriate biosafety level for well-characterized agents that do not cause disease in healthy humans is Biosafety Level 1 (BSL-1). BSL-1 is designated for work with agents that pose minimal risk to laboratory personnel and the environment. Activities conducted at this level include those with non-infectious strains or organisms that are unlikely to cause disease in healthy adults.

Biosafety Level 1 is suitable for educational and research settings where basic microbiological practices are sufficient. Typically, it involves the use of microorganisms that are understood, well-characterized, and do not have the potential to cause disease in humans. The staff working under BSL-1 conditions do not require specialized training, although they should be familiar with standard laboratory safety practices.

In contrast, the other biosafety levels, which include BSL-2, BSL-3, and BSL-4, are meant for agents that present varying degrees of risk to humans, necessitating additional safety precautions and containment measures. BSL-2 is applied to agents that can cause disease in healthy individuals, while BSL-3 and BSL-4 are designed for more dangerous pathogens, requiring increasingly robust containment strategies. Thus, BSL-1 is the correct choice for