Sterilization is the elimination of all life forms and transmissible agents (e.g. bacteria, fungi, viruses, and spore forms) from the surface of a material or from the composition of a fluid/compound. For certain industries with purity processes on a regular basis—the food & beverage industry and the pharmaceutical industry most especially—sterilization is a very important sub-process.

There are many ways a material can be sterilized, for example, some metal objects can be sterilized by cleaning the surface with acids or caustic solutions. However, in the case of single use products, gamma irradiation and ethylene oxide sterilization are 2 of the most common processes in use at the moment. So how do they compare? Below you will find out more about both processes: how they work, which materials they work best with, and the advantages and disadvantages of each process.

EtO Sterilization

Also known as Gas Sterilization, EtO sterilization is carried out by exposing the material(s) to the highly toxic and volatile ethylene oxide gas for a regulated and predetermined amount of time. In its pure form, ethylene oxide gas is flammable and explosive on exposure to air. As a result, it is usually diluted with inert gases to reduce its toxicity and make it easier to control.

The process

Before sterilization, the material needs to be preconditioned. This is done in a room that was specifically designed to heat and humidify the product to a stable temperature and moisture content before it is placed in the chamber carrying the EtO gas.

The sterilization process takes place in a vacuum-tight chamber and when all the air in the chamber is removed, a pre-calculated concentration of EtO that ensures optimum sterilization is introduced. The next step is the introduction of the material that is to be disinfected. While the process is ongoing, the time of exposure, as well as the temperature, concentration, and humidity of the gas is monitored constantly. 

When the process is complete, the material is washed several times at a controlled pressure to assure that the material, likely softened during the decontamination process, is not damaged and that it is safe for handling EtO sterilization is used mostly in hospitals and is ideal for plastics, but not so much for materials that absorb gases; these are likely to leach ethylene oxide into future processes, ruining them as a result.


  • A wide range of materials can be sterilized using this process.
  • Because EtO penetrates cartons and sealed films, already packed materials can be sterilized using the process.


  • Ethylene oxide is considered a carcinogenic and may have harmful effects on human beings.
  • The process has more variables that need controlling than gamma sterilization.
  • EtO is highly flammable and in the presence of air, the gas can produce its own oxygen.
  • Possible residual smell and discoloration of the materials.

Gamma Sterilization

Gamma radiation sterilization is done by exposing a material to a regulated dose of ionizing radiation (gamma rays).— The radiation breaks the covalent bond in the microorganisms’ DNA, causing mutation, and eventually, cell death, thereby freeing the material from contamination.

The Process

Materials to be sterilized using gamma rays do not need to be preconditioned, and  may be assembled and packaged before the process. The radiation  is applied in a safe and controlled environment, and a dose of radiation may take between a couple of minutes to a few hours to disinfect a material depending on the thickness/volume.

Gamma radiation is most suitable for acetyls (low doses of radiation), polycarbonates, acrylics, PVDF, etc., and it is the sterilization process of choice at industrial plants and pharmaceutical companies.


  • Gamma radiation is the ideal option for materials that are to be stored for an extended period of time.
  • The process does not generate heat or moisture.
  • It is more cost effective and more sterile than EtO sterilization.
  • After the sterilization process, there is no residual radioactivity.


  • After sterilization using gamma rays, some materials may be slightly discolored. However, this has no effect on performance, on the contrary, some plastics perform better after irradiation.

Both processes outlined above require a sterile environment where the processes can be carried out risk- and contamination-free. International Enviroguard, offers Gamma Radiated products and other protection solutions that help your workers remain uncontaminated as well as safe from toxic acids, gamma radiation, and other harmful substances.