Table 1. Comparison of Cobalt-60 Sterilization Alternatives.

Type of Sterilization	Advantages	Challenges
Gamma radiation	•    Can be used to sterilize health care products on a commercial scale 1   •    Simplicity and reliability of irradiation equipment, the radiation source and ability to match source strength to production throughput ( http://www. iaea.org/inis/collection/NCLCollectionStore/_ Public/07/220/7220308.pdf#page=280)   •    Scalability for different throughput   •    Reactor-produced from metal 59Co, and therefore has a finite production cost ( http://www. iaea.org/inis/collection/NCLCollectionStore/_ Public/07/220/7220308.pdf#page=280)	•    Not suitable for small scale 22   •    Requires requalification of irradiator operation after source replenishments 23   •    Some deleterious effects on patient-care equipment associated with gamma radiation include induced oxidation in polyethylene and delamination and cracking in polyethylene knee bearings 22
Electron beams (E-beam)	•    Can be used to sterilize health care products on a commercial scale 1   •    Near instantaneous dose delivery   •    Scalability for different throughput   •    Capability to integrate in an on-line process 3   •    Short processing time 23	•    Higher costs for accelerator investment and operations than gamma – not suitable for small scale 22   •    Complex irradiation equipment design and higher maintenance costs / downtime than Co-60   •    Low penetrability (bulk densities up to 0.25 g/cm3) 23   •    Dose distribution through the irradiated product is less uniform than with gamma radiation 1
X-rays	•    Comparable penetration to gamma rays 3, 23   •    Recent developments in high current e-beam accelerators for X-rays 3 make it more practical	•    Limited use, uncertain operating and usage cost estimates 3   •    Higher costs for accelerator investment and operations than e-beam and gamma – not suitable for small scale 22   •    Complex irradiation equipment design and potentially higher initial capital costs than gamma and higher maintenance costs / downtime than E-beam and Co-60 23   •    Accelerator source used for x-ray is less reliable than Co-60 for cargo container contraband and security screening applications ( http://www. iaea.org/inis/collection/NCLCollectionStore/_ Public/29/057/29057259.pdf)
Ethylene oxide	•    Widest range of material compatibility except for moisture and temperature-sensitive materials (>30 degrees C and/or <30% RH) 23	•    Hazardous (toxicity issues, explosive) 23   •    Long processing time 23   •    Many variables to control (temperature, time, pressure, vacuum, gas concentration, packaging and humidity) 3, 23;   •    Time-consuming for routine use between patients 22   •    Package and all parts of product to be sterilized must be gas permeable, irrespective of density 23
Steam	•    Preferred for aqueous preparations only 3;   •    Economical and short processing time;   •    Nontoxic and safe for the environment 12	•    Strict temperature and moisture controls;   •    Many variables to control (temperature, time, pressure, vacuum, packaging and humidity) 3;   •    Cannot be used for heat-sensitive materials 22
Peracetic acid- ethanol	•    Established sterilization of bone, dermis and amniotic membrane transplants with no evidence of impaired transplant properties 1   •    Rapid sterilization time 22   •    Less damaging process to delicate materials than steam;   •    Compatible with a wide variety of materials-plastics, rubber, and heat-sensitive items;   •    Single-use process, there is no possibility of contamination 12   •    Faster cycle times than EO 22	•    Has caused significantly reduced biomechanical strength and decreased remodeling activity in anterior cruciate ligament reconstruction tendon grafts 1   •    Lack of evidence on reduction in infection risk and link to improved patient care 22
Thermodisinfection	•    Found to preserve tensile strength necessary for clinical purposes 1, 27	•    Small-scale
Microwave	•    Effective for sterilization of bone allografts processed from femoral heads contaminated with Gram-positive and Gram-negative bacteria 1	•    Lack of evidence on efficacy 1   •    Can only be used with items that do not melt 22