Compounding hazardous topical products must be performed in an ______ vented minimum Class 1 BSC.

• A. Internally
• B. Partially Externally
• C. Externally
• D. Not Vented

Answer: (C)

The key safety idea is that hazardous topical drug aerosols must be removed from the breathing zone and the work environment. Externally vented exhaust directs any vapors or aerosols generated during compounding outside the building, rather than circulating them back into the room. This external exhaust reduces the chance that staff will inhale hazardous drug particles and protects the surrounding area as well.

If the cabinet is not vented externally, or if only part of the air is vented, aerosols can linger in the room or be recirculated through the HVAC system, increasing exposure risk. Not venting at all would leave hazardous substances in the work area, which is unsafe. Therefore, using an externally vented minimum Class I BSC provides the necessary containment to protect personnel during hazardous topical compounding.