Principle, Procedure, Merits, Demerits and Applications of Chemical Methods of Sterilization

Chemical Sterilization

• Chemical sterilization involves using chemical bactericidal agents in order to kill microorganisms.
• Despite the fact that physical sterilization is the best option for effective sterilization, it is not always appropriate for heat-sensitive materials, such as plastics and fiber optics.
• Sterilization can be achieved using chemicals that are either liquid or gaseous. Nevertheless, it is important that the chemicals used in the sterilization are compatible with the materials undergoing sterilization.
• Additionally, safety rules should be established during the use of chemical agents at the workplace.
• Liquid and gaseous sterilization are two chemical methods of sterilization.

Gaseous Sterilization

• In a closed pressurized or heated chamber, equipment or devices are exposed to different gases for sterilization.
• Sterilization using gases is more effective due to the ability for gases to pass through tiny orifices and provide better results.
• In addition, the use of gases is frequently accompanied by heat treatment, which facilitates their functioning.
• It is however necessary to remove some toxic gases from the system periodically due to the release of some toxic gases during the process.
• The mechanism of action varies depending on the gas.

Liquid Sterilization

• During liquid sterilization, instruments are submerged in liquid sterilant to destroy all spores and all viable microorganisms.
• It is acceptable to use liquid sterilization when there is a low level of contamination when gaseous sterilization is not as effective.

Advantages and Disadvantages of Chemical Sterilization

Advantages

Various advantages and disadvantages exist with gaseous sterilization. An ethylene oxide gas has many advantages, such as its high penetration capability and ability to pass through most types of barrier packaging. It is also possible to sterilize an item more than once without damaging it (although the material matters). By contrast, gaseous sterilization does not cause embrittlement like radiation (which can, especially during repeated applications, cause material damage) and steam (where repeat applications can damage materials). Ethylene oxide is also advantageous because it has a greater degree of adjustable parameters than steam or radiation, which restrict the way the parameters can be adjusted. By adjusting the parameters of the ethylene oxide cycle, the parameters of the device can be assessed in terms of their thermal or moisture sensitivity. The use of ethylene oxide in sterilizing a variety of materials is also possible. Sterilization with steam or gamma radiation may degrade polymers and change physical or mechanical properties, which could compromise the performance of the product.

Disadvantage

• Inflammable
• Pungent
• Teratogenic
• Carcinogenic
• Toxic
• Low penetrating power
• Skin, conjunctiva, and nasal mucosal irritation are some signs of acute toxicity.

Toxins must be removed from ethylene oxide through strict adherence to the aeration step at the end of sterilization, which is one of the biggest disadvantages of the gas. As the gas is also potentially hazardous to people (it is mutagenic and explosive), strict health and safety standards must be observed throughout the process. Another disadvantage occurs if the wrong material is used or if the validation process has not been carefully outlined, resulting in residues that can create toxicity in chemicals or alter their nature. The nature of the packaging and the nature of the material in which ethylene oxide is used can influence the concentration of gas residues present in ethylene oxide. Additionally, ethylene oxide can be environmentally harmful if the process uses chlorofluorocarbons, since the gas chamber method releases these chemicals into the environment upon combustion. After use, ethylene oxide must be disposed of properly according to national safety regulations (such as an exhausted mixture of ethylene oxide and water).

Applications of Chemical Sterilization

Sterilization with chemicals is usually used when the high heat required for steam sterilization would damage sensitive devices, or for devices that may be damaged by irradiation (rubbers and plastics become brittle with irradiation).