The disadvantages of sterilization via chemical processes are the facts that: some materials, such as plastics, absorb large amounts of chemicals, while others, such as stainless steel, absorb none. The more the chemical is absorbed by the material the longer is the aeration process.
This is neither time, nor cost effective.
Complex designs are hard to sterilize via chemical process since some parts of the device may have limited accessibility that is they will not be completely sterilized. Another concern is the fact that chemicals can not penetrate all packaging and only several millimeters of material.
The only exception is ethylene oxide sterilization, however it is an expensive and complex process and requires thorough anti-pollution measures since the gas is very poisonous.
The increasing cost of the gas and of the various engineering and environmental controls required to assure safe low residual products and low personnel exposure has raised the cost of ethylene oxide (EtO) sterilization which results in it being a very disadvantageous process.
The advantages of radiation sterilization over other techniques is the fact that the powerful gamma rays are able to penetrate through the products of any shape and size as well as any outside packaging. This means that the products can be individually pre-packed in sealed bags and sterilized fully packaged, ensuring that the product sterility is retained provided the package is undamaged. This gives radiation sterilization an advantage over the boiling and chemical methods, which are unsuitable for complex items with a lot of hard to reach and dense areas. An advantage of radiation sterilization is the fact that it is a cold process, therefore, heat sensitive products that could be damaged using the dry heat method, can safely be sterilized using gamma radiation. Another benefit of radiation sterilization is the speed and cost. Since this is a continuous and fully automated process and only the timing of the exposure needs to be controlled, this is much more time effective that steam and chemical processes. A further advantage is that products may be released for sale based on documentation that the desired dose of gamma radiation was delivered. Microbiological release testing generally is not required unless it is a local regulatory requirement.
Many of these products are unable to be sterilized using steam or heat. Heat because it has a long processing time and the high temperature limits the types of products and packaging materials compatible with this process. Steam is unsuitable for complex items due to the its inability to reach sealed off and highly dense components. A further problem is steam’s ineffectiveness for products that are moisture sensitive or water resistant.
Once treated these sterilized instruments ARE NOT radioactive and are safe for use. This is because the energies given out by the decay of Cobalt 60 are insufficient to induce radioactivity in any material, irrespective of the length of exposure to the source.
Cobalt-60 is produced by the process of artificial transmutation. The naturally occurring and stable isotope of cobalt-59 is irradiated with neutrons. Some of cobalt-59 nuclei absorb neutrons and this results in cobalt-60 being produced. The unstable cobalt-60 offloads some of its excess energy by releasing gamma radiation – high frequency electromagnetic radiation.
