Radioactive Sources Applications and Alternative Technologies (2021) / Chapter Skim
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5 Radioactive Sources and Alternative Technologies in Sterilization
5 Radioactive Sources and Alternative Technologies in Sterilization
Pages 97-114
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From page 97... ...
The applications discussed include sterilization of medical devices and health care products to eliminate microorganisms (Section 5.2) , irradiation of food and agricultural products to eliminate harmful bacteria and a variety of microorganisms and insects or to extend their shelf life (Section 5.3)
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The sterilization market, particularly for medical devices, is operating at or near capacity1 but the industries that these facilities serve are growing. Traditionally, cobalt-60 has been the most commonly used radioisotope in industrial sterilization.
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Importantly, medical device manufacturers have experience with the requirements to validate this modality of sterilization for new products. There are approximately 200 large gamma irradiation facilities worldwide in more than 50 countries that are predominately used for medical device sterilization.
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From page 100... ...
Expansion of production capacity for a facility that has radioactive sources such as a cobalt-60 gamma sterilization facility can be achieved simply by adding source elements to those already in place in the facility. This is an advantage over the expansion process for e-beam and x-ray facilities, which are typically designed to run at a FIGURE 5.1 Typical gamma irradiator.
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5.2.2 Alternative Technologies As noted earlier, e-beam irradiation, x-ray irradiation, and EtO fumigation are modalities currently used for medical device sterilization. These methods are not necessarily a direct replacement for one another.
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X-ray Technology Accelerators used as a high-energy photon sources (1–10 MeV) could be the most straightforward replacement of gamma irradiation because the radiation penetration in the two modalities is similar.
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5.2.3 Alternative Technology Adoption Considerations Increasing concerns about cobalt-60 source availability and EtO emissions and residuum levels, together with other factors, have put pressure on medical device suppliers to look for alternative technologies to meet demand for device sterilization. Several industry representatives who briefed the committee, as well as other experts, project that utilization of e-beam and x-ray irradiation sterilization will increase to cover market demand that will probably not be covered by gamma irradiation.
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From page 104... ...
Instead, all major medical device sterilization modalities -- gamma, e-beam, x-ray, and EtO -- are expected to contribute to the reliability of the market. Transitioning from gamma irradiation to e-beam and x-ray irradiation for sterilization is theoretically straightforward because all are approved sterilization methods that are recognized by an established standard (ISO 11137)
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From page 105... ...
FDA has approved a variety of foods for irradiation in the United States including beef, pork, poultry, crustaceans, fresh fruit and vegetables, shell eggs, and spices and seasonings. However, very little food is currently irradiated in the United States for food safety primarily because of lack of public acceptance of irradiated food (see discussion in Section 5.3.3)
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From page 106... ...
but nonspecific to the food product, which simplifies the applied protocol when compared with other phytosanitary treatments. Most food and agricultural products treated by irradiation are processed in facilities using gamma radiation from cobalt-60.9 These facilities typically are not dedicated facilities but instead multipurpose facilities primarily used for medical device sterilization.
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From page 107... ...
For example, in Africa, except in Egypt and South Africa, the lack of resources and basic infrastructure cannot support food irradiation technologies at the scale necessary to be effective. Other actions are more urgent than irradiation to enhance food safety in African countries, including improving handling, transportation, and food storage conditions.
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From page 108... ...
These perceptions include concerns that irradiated food makes food radioactive and therefore can cause cancer and that irradiation changes the chemical composition of the food or that it diminishes the nutritional value of the food product (Castell-Perez and Moreira, 2021)
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. FIGURE 5.4 Insect pest control by the use of sterile insect technique.
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Most SIT programs use cobalt-60 gamma rays. Gamma-based SIT can take place in sterilization facilities using panoramic irradiators or using smaller selfcontained dry-storage irradiators; most of these facilities are dedicated facilities used for SIT purposes only.20 The largest program that uses gamma irradiation is in Guatemala and can produce 3 billion sterile males per week primarily for use in the United States (California and Florida)
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From page 111... ...
can be suitable replacements for radioactive sources for smaller SIT programs that irradiate fewer than 100 million insects per week. Testing of x-ray machines around 2008, at the Insect Pest Control Laboratory of the FAO/IAEA Agriculture and Biotechnology Laboratories in Seibersdorf, Austria, revealed issues with the reliability of the x-ray tube (IAEA, 2012a)
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. 5.4.3 Alternative Technology Adoption Considerations Migration from gamma irradiation to other modalities for SIT is needed because of the challenges with acquiring and transporting radioactive sources for insect sterilization, as described in Section 5.4.1.
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From page 113... ...
Several companies have also announced plans to open new x-ray sterilization facilities. Alternative technologies for other sterilization applications, including food irradiation for safety and phytosanitary treatments and insect sterilization, are also increasingly accepted as viable replacements for radioactive sources in many countries.
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