RADIATION METHOD OF STERILIZATION
Radiation or ultraviolet light sterilization: this method is expensive. But nowadays it is used for the sterilization of plastic items such as disposable saline set, catheter, Ryle’s tubes, etc
Gas sterilization: ethylene oxide gas is employed as a sterilizing agent in especially designed chambers in which temperature and humidity can be controlled and from which air can be evacuated
After exposure period of 3 to 6 hours is needed. Other gases employed for sterilization are formaldehyde and betapropiolatone
Articles Sterilized
- Surgical instruments with optical lenses
- Tubing and plastic parts of heart lung machines
- Ventilator tubes
- Disposable syringe
- Pillows and mattresses
Advantages
- Exposure to formaldehyde gas under conditions of controlled humidity, temperature, and the time exposure will destroy all vegetative forms of bacteria, viruses, and most of the spores
- The best results can be obtained with high concentration of gas humidity above 60% and temperature of not less than 180 degree celcius
Disadvantages
- Ethylene oxide has a pungent smell
- It is an irritant to eye, mucous membrane and skin
Radiation Method
There are two type of radiation are non-ionizing radiation and ionizing radiation
Non-ionizing radiation methods are infra-red and ultra-violet radiation
Ionizing radiation methods include X-rays, gamma rays; and cosmic rays are highly lethal to DNA and other vital cell constituents
Advantages
- Instruments like disposable syringe catheters hypo-dermic needles and sharp instruments that cannot withstand heat, can be sterilized by this method
- Instruments which are covered in plastic packs or aluminum foils can be sterilized by this method
Disadvantages
- Since radiation in a straight line and do not penetrate only the surface of an object in straight line is irradiated
- The bacteria in shadows are unaffected, so all the surfaces should be exposed to the radiation
