Sub-process irradiation of naturally contaminated hypodermic needles

The proportion of nonsterile hypodermic needles within a population of needles (P), contaminated initially with native microflora, has been measured as a function of gamma-radiation dose (D) over the range 0 - 4 kGy. The relationship between P and D was regular and allowed extrapolation to higher doses corresponding to the generally accepted probability of occurrence of a nonsterile item or sterility assurance level (SAL), and beyond. An absorbed dose of 7.5 kGy was estimated to be sufficient to give a value of P of 10-6, whereas a dose of 25 kGy would be expected to give a P of 10-18. (author)