A hospital supply unit uses ethylene oxide gas to sterilise large lots of disposable plastic intravenous sets. Which parameter is essential for the sporicidal activity of ethylene oxide?

• A Complete absence of water vapour in the chamber
• B Chamber temperature above 100 degrees Celsius throughout the cycle
• C Relative humidity of at least 30 percent during the exposure period ✓
• D Exposure limited to 15 minutes to prevent product degradation

Explanation

Ethylene oxide kills microorganisms by alkylation of proteins and nucleic acids, and this reaction requires moisture, hence a relative humidity of roughly 30 to 80 percent must be maintained in the chamber. The process runs at mild temperatures of about 37 to 63 degrees Celsius, making it suitable for heat-labile plastics. Complete drying abolishes activity, and cycles require several hours of exposure followed by aeration to remove residual toxic gas.

Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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