The EtO sterilisation process comprises of pre-packed products being loaded into a specially designed chamber, exposing them to EtO under controlled conditions and unloading them from the steriliser after aeration. 

The process is a terminal process and is carried out on pre-packed goods (the last step in the manufacturing cycle); this ensures product sterility. Commercially, the quick turn-around results in lower inventories! 

EtO is an effective sterilant at low temperature with excellent penetration properties under controlled conditions. EtO is a gas at ambient temperature since it vapourises at about 10.7°C (51.3 deg F). Being an effective sterilant it destroys all micro-organisms at room temperature. 

EtO is a tiny molecule in which two carbon and four hydrogen atoms are joined to one oxygen atom in a highly strained epoxy ring. Because of the chemical's low boiling point (10.7 deg C, ~51.3 deg F) it vapourises and permeates rapidly through packaging and diffuses in products made of cotton, plastic and rubber. EtO readily kills all types of micro-organisms under ordinary atmospheric conditions. Its fragile molecular bonds allow it to quickly react with a wide variety of enzymes. The resulting chemical reaction is called alkylation. 

Spores, as is well known are more resistant to disinfectants but with EtO, spores are not as hard to kill. The use of EtO as a sterilising agent, its related toxicity studies and residual influence have been well documented. After careful study various countries have given distinct guidelines in their respective Standards on use of EtO as a sterilising agent. In India, the Bureau of Indian Standards have published guidelines for sterilisation of medical products (IS 10150-1981) indicating EtO as a sterilising agent for medical devices. 

The ability to treat items in sterilant-permeable packaging permits sterility maintenance as long as integrity of the packaging is maintained. 

Gamma rays are short waves of considerable energy that affects products in two ways:

1. Directly causes large molecules (DNA & RNA) to disintegrate into smaller molecules thereby preventing growth of the cell.

2. Causes radiolysis of water producing free radicals that react with chemical groups inactivating them