A manufacturer needs to sterilise prepacked disposable plastic syringes in their final sealed containers. Ionising radiation is selected. Which dose is the internationally accepted standard for this application?
- A 0.25 megarad (2.5 kGy)
- B 2.5 megarads (25 kGy) ✓
- C 25 megarads (250 kGy)
- D 250 megarads (2500 kGy)
Correct answer: B. 2.5 megarads (25 kGy)
Explanation
Gamma irradiation from a cobalt-60 source at a dose of 2.5 megarads, equivalent to 25 kilograys, is the accepted standard for sterilising disposable plastic syringes, catheters, sutures and similar single-use items in sealed packs. Being ionising radiation, gamma rays act by producing lethal free radical damage to DNA, penetrate well and leave no residue or heat load. Ultraviolet light is non-ionizing and lacks penetrating power, so it cannot sterilise packaged goods, and the other doses given are tenfold errors.
Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.