Filling Data Gaps Related to Material Effects in Polymer Medical Products from E-beam and X-ray Sterilization*

Gamma ray treatment predominates among current medical device radiative sterilization methods. However, there are potential nuclear security concerns associated with Colbalt-60 gamma radiation; E-beam and X-ray methods may serve as safe future alternatives. To this end, 88 samples of medical devices (vacutainer (VT) and push button (PB)) and 2000 dog bones made of polyvinyl chloride (PVC), polypropylene homopolymer (PPH), polyethylene terephthalate (PET), low-density polyethylene (LDPE), polyolefin elastomer (POE) and chlorinated isobutylene isoprene rubber (CIIR) have been irradiated by gamma ray, X-ray, and E-beam with doses ranging from 0kGy to 80kGy. Functionality of the medical products was tested before and after treatment, and raw material tensile strength and hardness was measured. Yellowness index measurements indicate no dependence on irradiation modality; color variation depends on type of polymer and dose, since component polymers respond differently to treatment (formation of carbonyl species, double bonds, conjugated free radicals). Overall, the investigated relationship between type of radiation source and observed chemical and physical changes show that E-beam and X-ray are safe alternatives to gamma ray sterilization of medical products.