Frequently asked Question about ETO Sterilizer and ETO Sterilization

Below are most frequently asked question about ETO Sterilizer and ETO Sterilization process

What is sterilization?

Sterilization is a phrase referring to any process that eliminates or kills all forms of microbial life, including transmissible agents (such as fungi, bacteria, viruses, spore forms, etc.) present on a surface, contained in a fluid, in medication, or in a compound such as biological culture media. Sterilization can be achieved by applying the proper combinations of heat, chemicals, and irradiation, high reassure, and filtration.

The term has evolved to include the disabling or destruction of infectious proteins such as prions related to Transmissible Spongiform Encephalopathy (TSE).

Type of Sterilization Methods:

There are mainly following sterilization methods are in use

  • Heat based Sterilization
  • Chemical based Sterilization
  • Radiation sterilization

What is ETO Sterilization?

  • ETO Stands for Ethylene Oxide Sterilization
  • Ethylene oxide sterilization is a type of chemical process consisting of four primary variables namely gas concentration, humidity, temperature and time.
  • Ethylene oxide is an alkylation agent that disrupts DNA of microorganisms, which prevents them from reproducing.
  • ETO sterilization assures that a safe and sterile product will be delivered to the market each and every time.

Why & where ETO Sterilization used?

  • World / industries have been praising sterilization by steam & superlative for destroying bacteria, fungi and spores.
  • Steam sterilization is also most cost effective & easy to use method available but steam is not applicable to all materials and instruments.
  • Advancement in medical procedures has resulted in the increased usage of delicate instruments which cant be steam sterilized as they cannot survive excessive temperatures or moisture of steam. So Heat and moisture sensitive equipment require alternative methods of sterilization. And that is where ETO Sterilization is used.

Fact about ETO Gas:

  • ETO gas is carcinogenic, explosive and mutagenic.
  • Ethylene Oxide (EtO) is a common gas used for low temperature sterilization.
  • It is a colorless, poisonous gas that attacks the cellular proteins and nucleic acids of microorganisms.
  • It is most commonly used to sterilize instruments with long lumens such as endoscopes and all materials that have to be sterilized but cannot withstand higher temperature.
  • EtO process temperatures from 25 - 55C are used. A lower temperature results in a less efficient process which leads to a longer exposure time.
  • EtO sterilization should be used only when another method is not appropriate.

What is ETO Sterilizer?

  • ETO Sterilizer is equipment, which facilitate ETO Sterilization process.
  • ETO Sterilizers are available in various capacities from 0.45m3 to 44m3 volumetric capacities to carry out ETO Sterilization.

How is sterilization cycle in ETO Sterilizer?

There are 3 phase in ETO Sterilizer

  • Preconditioning
  • Sterilization
  • Aeration (Degassing)
  • Cycle time is usually more than 14 hours.

Advantages of EtO are:

  • Low temperature
  • High efficiency destroys microorganisms including resistant spores
  • Large sterilizing volume/ chamber capacity
  • Non corrosive to: plastic, metal and rubber materials


  • Excessively Long cycle
  • Safety concerns - carcinogenic to humans
  • Toxicity issues - toxic residues on surgical instruments and tubing
  • Not recommended for flexible scope
  • EtO is flammable
  • Requires special room conditions, safety equipment and separate ventilation system
  • Relatively high annual costs for maintenance, servicing and consumables.