Final answer:
Option D). Level 4 toxicity indicates a hazardous material spill that requires prompt medical treatment. BSL-2 is suitable for moderate risk agents and requires specific safety precautions such as biohazard signage.
Step-by-step explanation:
Level 4 (D) is the toxic level that denotes a hazardous material spill that necessitates immediate medical attention. Level 4 (BSL-4) of the biosafety hierarchy refers to hazardous or unusual agents that pose a significant risk of life-threatening illness. Precautions including biohazard warning signs, protective gear, and proper disposal procedures for biological materials, such as bacterial cultures on agar plates, must be followed when working with BSL-2 agents, which are regarded as moderate risk, in order to ensure safety and prevent exposure to or ingestion of infectious material.
- Biosafety level 2 (BSL-2) is appropriate for research with microbes or infectious agents that pose moderate risk to laboratory workers and the community, and these are usually indigenous agents.
- Primary hazards in a BSL 1 or 2 laboratory include accidental skin punctures, mucous membrane exposure, and accidental ingestion of infectious material.
- Biohazard warning signage is required when working with BSL 2 agents to prevent unauthorized entry and to inform individuals of the potential hazards.