Gaseous ethylene oxide sterilization

The most common sterilization processes are gaseous ethylene oxide (EtO), gamma radiation, and autoclave sterilization. The resistance of adhesives to these processes will be dependent on the conditions of the sterilization cycle as well as on the chemistry of the adhesive. 

Phillips, C.R. Kaye, S. The sterilization action of gaseous ethylene oxide. I. Review. Am. J. Hyg. 1949, 50, 270-279. Alguire, D.E. Yeung, A.C. Making cosmetics microbiologi-cally safe. Cosmet. Toiletries 1979, 94, 77-80. 

Ernst, R.R. Doyle, J.E. Sterilization with gaseous ethylene oxide a review of chemical and physical factors. Biotech-nol. Bioeng. 1968, 10, 1-31. 

Sterilization. Sterility Is a necessary requirement for all membrane devices used clinically, and the sterilization procedure must not change the functional or blocompatlble character of the device. Sterility, the condition of absolute absence of viable life forms, can be achieved by physical (heat. Irradiation) or chemical means. Chemicals used to sterilize membrane devices may be either gaseous (ethylene oxide) or liquid (formaldehyde, peroxides, hypochlorite) In nature. The generally accepted... 

There are four ways in which ethylene oxide may be retained in products at the end of sterilization cycles. These are as gaseous ethylene oxide, as. ethylene oxide dissolved in water, as ethylene oxide within but not attached to the product or packaging material, and as molecularly adsorbed or absorbed ethylene oxide [13]. The total amount of residual ethylene oxide and the balance among the four forms of residue at the end of sterilization are functions of the sterilization process conditions, the composition of the product, the size of the product, the packaging materials, and the packing density. Dissipation of residues after sterilization is a function of the product- and packaging-related factors listed above plus the conditions in which the product is being held (aeration). 

The amount of residual ethylene oxide in a product can be signiflcantly influenced by sterilization process conditions. Gas concentrations and exposure times within the exposure period of the cycle should be sufficient to achieve sterility, but their effects on residues should be considered before prolonging them unnecessarily. Importantly, free gaseous ethylene oxide is easiest to remove from product loads, and this is best addressed by postexposure evacuation and aeration. Multiple evacuarians and forced circulation aeration at temperatures around 30 C have been found to be effective. The effects of increased temperatures extend beyond the removal of the free gas to the removal of other forms of bound ethylene oxide. 

Gaseous ethylene oxide (EtO). Exposure to ethylene oxide, admixed with a carrier gas such as carbon dioxide or a chlorofiuorocarbon, is the most widely used sterilization process because it has the least damaging effect on materials and devices and is low cost. EtO sterilization is a room-temperature process that affects only the external surfaces of a module. 

Ethilenevinylalcohol (EVAL) is used to prepare hydrophihc symmetric low-flux membranes, usually sterilized by means of gaseous ethylene oxide (EtO) or y-ray irradiation. Details on membrane preparation are not available. Their surface oxygen content has been reported to reduce protein adsorption and activation of the humoral system as compared to RC membranes. 

Gaseous sterilization Ethylene oxide (EO) Reactive chemical Indicator paper impregnated with a reactive chemical which undergoes a distinct colour change on reaction with EO in the presence of heat and moisture. With some devices rate of colour development varies with temperature and EO concentration Gas concentration, temperature, time (selected devices) NB a minimum relative humidity (rh) is required for device to function... 

Ernst, R.R. Shull, J.J. Ethylene oxide gaseous sterilization. I. Concentration and temperature effects. Appl. Microbiol. 1962, 10, 337-341. 

Ethylene oxide (bp, 10.8°C) is a gaseous alkylating agent. It alkylates proteins and ribonucleic and deoxyribonucleic acid in micro-organisms. It replaces labile hydrogen with hydroxyethyl groups. Ethylene oxide is utilized as a surface sterilant. Bulk crystalline materials can occlude vegetative bacterial cells or spores with crystals. Consequently, ethylene oxide does not reach them. The final step prior to sterilization is an aseptic recrystallization step. 

Ernst, R. R. (1973). Ethylene oxide gaseous sterilization for industrial applications. In Industrial Sterilization (G. Briggs Phillips and W. S. Miller, eds.). Durham, N.C. Duke University Press. 

Sterilization can be achieved by moist or dry heat, by ethylene oxide (or other suitable gaseous sterilizing agent), by filtration with subsequent aseptic filling of sterile final containers, or by irradiation with ionizing radiation (but not with ultraviolet radiation unless the process is thoroughly validated). Each method has its particular applications and limitations. Where possible and practicable, heat sterilization is the method of choice. 

STERILISATION (1) A process intended to produce sterile goods. (2) Reduction of the probability of the presence of viable micro-organisms to an acceptable extent. Sterilisation is effected by moist or dry heat by treatment with a gaseous sterilant such as ethylene oxide, by irradiation with ionising radiation or, where such processes are inapplicable to solutions, by filtration. 

Ethylene oxide is used for the gaseous sterilization of disposable medical instruments. When the 2 -deoxyguanosine groups of a microorganism s DNA react with ethylene oxide, they are alkylated (see page 514), and the microorganism can no longer reproduce. 

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