Ethylene oxide – Sterlization, Structure, Uses

Ethylene oxide has strong penetrating power to disinfected items, it can reach the deep part of items, and can kill several pathogenic microorganisms, including bacterial propagules, spores, viruses, and fungi.

Ethylene oxide is one of the important organic synthesis raw materials. Used in the manufacture of glycols, synthetic detergents, emulsifiers, non-ionic surfactants, antifreeze, plasticizers, lubricants, pesticides, and as a warehouse fumigant.

What is ETO (Ethylene oxide)?

  • Ethylene oxide is an odorless gas, composed of C, H, and O (C2H40). which is capable of eliminating microorganisms in a very short time.
  • Ethylene oxide is slightly sweet in taste when it is very concentrated.
  • Ethylene oxide is easily soluble in water.
  • Small amounts of ethylene oxide are also produced when burning tobacco. Very small amounts of ethylene oxide can be found in nature.
  • It is used at normal temperatures: 30-55°C.
  • It is used in gaseous sterilization, generally in the pharmaceutical industry.
  • Ethylene oxide is a flammable and explosive poisonous gas. Inhalation of ethylene oxide can cause anesthesia, poisoning.
  • Ethylene oxide is a toxic carcinogen.
  • At 4°C, the relative density is 0.884, the boiling point is 10.8°C, and its density is 1.52g/cm³.
  • Most of the ethylene oxide is used to make other chemicals, mainly ethylene glycol.
  • When the concentration is too high, it can easily volatilize into gas and When the concentration is too high it can cause an explosion.
  • Ethylene oxide is 27 times more toxic than ethylene glycol and similar to ammonia.
  • Ethylene oxide sterilizers are used to sterilize heat- and moisture-sensitive Pharma and Medical devices which are made up of plastic and rubber.
  • It is widely used in the washing, pharmaceutical, printing, and dyeing industries.
  • Ethylene oxide is also widely used to sterilize medical supplies such as bandages, sutures, and surgical instruments.
  • Ethylene oxide kills bacteria (and their endospores), mold, and fungi, so it can be used to sterilize some items that cannot withstand high-temperature sterilization.
  • Ethylene oxide is the second most important product after polyethylene as an industrial derivative of ethylene. Its importance is mainly due to the series of products produced from it.

Ethylene oxide Structure

Ethylene oxide, Sterlization, Structure,  Uses

Ethylene oxide (ETO) Sterilization

  • Ethylene oxide has strong penetrating power to disinfected items, it can reach the deep part of items, and can kill several pathogenic microorganisms, including bacterial propagules, spores, viruses, and fungi.
  • Both types of gas and liquid have strong microbicidal effects, and gas has a strong effect, so its gas is mostly used.
  • The ethylene oxide sterilization process distinguish into 4 phases: Conditioning, gas exposure, Gas evacuation, and Aeration.
  • Once the material has been sterilized by ethylene oxide, it is subjected to an aeration process to remove any ethylene oxide that might remain in the material and ensure that it is not toxic to the patient.
  • Even today some sterilizers are incapable of aerating the material. In these cases, once the pressures inside and outside the sterilizer are equal, the material is immediately removed and transferred to a special oven that will perform aeration.
  • In an oven, with hot air, the ethylene oxide is removed more quickly. For example, with air at 30°C, it takes about 6 hours to remove, while if it is at 60° it will take only 3 hours to eliminate it.
  • Textiles and cotton should never be sterilized using ethylene oxide. They are so porous that no matter how much we air them, it will be difficult to remove the ethylene oxide that impregnates them.
  • Currently, Ethylene oxide kills bacteria, endospores, mold, and fungi, so it can be used to sterilize some items that cannot withstand high-temperature sterilization.

Material that can be sterilized with ethylene oxide

  • Fine instruments for surgery and ophthalmology.
  • Endoscopes and their accessories.
  • Optics and cameras.
  • Plastic tubes that do not withstand high temperatures…Gloves and syringes.
  • Specialized surgery engines.
  • Electrical cables (electrodes, pacemakers).
  • Electric scalpels.
  • Silicone prostheses, etc.
  • Electronic equipment.
  • Cardio-respiratory pumps. metal etc.
  • It is used to sterilize thermo-sensitive materials such as disposable (rubber, plastic, paper, etc.).

Ethylene Oxide Uses

  • Ethylene oxide is very effective and it can sterilize material that cannot withstand high temperatures (autoclave-oven).
  • Ethylene oxide is used as a chemical intermediate in the manufacture of many products such as ethylene glycol.
  • Ethylene oxide is also used in the production of solvents, Cosmetic, detergents, adhesives, antifreeze, textiles, pharmaceuticals, etc.
  • Ethylene oxide is also used as a sterilizing agent for medical equipment and a fumigating agent for spices.
  • One of the major use of Ethylene oxide is used in the dried fruit industry to stop microbial spoilage.
  • Ethylene oxide sterilization is a safe and effective method that helps to ensure the safety of the medical device and helps to deliver good quality patient care.
  • Ethylene oxide is also used in the sterilization of food, and preservation of agricultural products.

Ethylene oxide Side Effects

  • It is very dangerous because it is highly flammable and explosive, and also carcinogenic.
  • Since ethylene oxide is colorless and odorless, if there is a leak it will be very difficult to detect.
  • This gas is toxic by the respiratory route and by contact.

Safety and prevention measures in sterilization with ethylene oxide

  • The ethylene oxide sterilizer will be located in the sterilization center, in a special area, and we must not enter the premises while the sterilization process is being carried out.
  • The increased risk of exposure to ethylene oxide depends on the type of sterilizer:
  • Modern sterilizer that performs the aeration phase. Once we stop it, it will take a minute for the door to open automatically.
  • We must take advantage of that minute to leave the room where the sterilizer is located.
  • We will let 15 minutes pass, and remove the material from the sterilizer.
  • we will use personal protection measures: nitrile gloves, rigid masks, and eye protection glasses. Remember that ethylene oxide is toxic by contact and by inhalation.
  • Sterilizer that does not carry out the aeration phase. In this case, we will enter the room with the same personal protection measures and as soon as the process is finished, we will open the door and remove the material as quickly as possible and introduce it into the aeration stove.

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