Steam sterilization uses steam contact at high temperature and pressure to kill microorganisms. Key parameters are steam, pressure, temperature, and time. Dry heat sterilization exposes items to extremely high uniform temperatures for extended times to penetrate via conduction. Chemical sterilization uses chemicals like chlorine and formaldehyde to terminate microbes, but they have limited penetration and potential health hazards. Each method has advantages like cost or speed but also disadvantages like material damage, toxicity, or lengthy exposure times required. Proper protocols must be followed for chemical sterilization in healthcare settings due to risks.

1. Infection control
diploma
Papered by :Tmomen Almanori
Under Supervision of Dr Hatem Al-bitar
Assignment 8

2. Compare between steam dry heat and chemical sterilization?
Steam sterilization
The basic principle of steam sterilization, as accomplished in an autoclave, is to expose each item to
direct steam contact at the required temperature and pressure for the specified time.
Thus, there are four parameters of steam sterilization: steam, pressure, temperature, and time.
The ideal steam for sterilization is dry saturated steam and entrained water (dryness fraction
≥97%).Pressure serves as a means to obtain the high temperatures necessary to quickly kill
microorganisms.
Specific temperatures must be obtained to ensure the microbicidal activity. The two common steam-
sterilizing temperatures are 121°C (250°F) and 132°C (270°F).
These temperatures (and other high temperatures)must be maintained for a minimal time to kill
microorganisms.
sterilization times vary depending on the type of item (e.g., metal versus rubber, plastic, items with
lumens), whether the item is wrapped or unwrapped.
Portable (table-top) steam sterilizers are used in outpatient, dental, and rural clinics These sterilizers
are designed for small instruments, such as hypodermic syringes and needles and dental instruments.
The ability of the sterilizer to reach physical parameters necessary to achieve sterilization should be
monitored by mechanical, chemical, and biological indicators.

3. Advantages of steam sterilization:
1 moisture in steam is a good conductor of heat and is superior at penetrating the Load.
2 less energy need
3 non-toxic
4 inexpensive
5 rapidly microbicidal sporicidal.
Disadvantages:
1- Presence of moisture on some metallic equipment makes them rust.
2- not ideal for hate sensitive material and moisture intolerance.

4. Dry heat sterilization :
dry heat is a simple process where loaded items are placed into a heating cabinet or conveyor tunnel.
Items to be sterilized are then exposed to high temperatures for an extended time, and filtered air blower fans enable the heat
to be uniformly distributed in the sterilizer.
Dry heat penetrates to interior surfaces of items via conduction.
Air is a poor heat conductor, which is one reason why dry heat sterilization is so slow. Heat transfer through the air is much
slower than heat penetration through steam heat because of the long exposure times required to kill spores.
The long exposure time needed to kill spores .
The high temperatures necessary for dry heat sterilization often cause material degradation, which is why dry heat is used as a
sterilization method for only a few applications.
The greatest problem with sterilization by dry heat is that the sterilization process is slow. Thus, dry heat sterilization can only
sterilize items capable of holding their integrity at high heat for long periods. Overall, dry heat sterilization is a common method
for glass, metal, and some dry powders. Sterilization by dry heat kills microbes through exposure to extremely high temperatures,
170◦C or more, for long periods of time. The benefits of dry heat sterilization are that a lengthy holding time at high temperatures
(250 ◦C) also kills off pyrogens (endotoxins).

5. - Advantages
- 1 inexpensive
- 2 it does not pollute it or cause toxic fumes
- 3 does not corrode or rust metal objects
- Disadvantages:
- 1 take much more time to achieve sterilization than other methods.
- 2 it can cause warping to sensitive material or thin sheets.
- 3 irreversible damage to plastics rubbers so not suitable for dry heat.

6. Chemical sterilization:
Chemical sterilization involves the utilization of certain chemicals so as to cause microbial
termination.
For this, the most used materials are chlorine, formaldehyde, glutaraldehyde, quaternary ammonium
salts.
However... these are majorly restricted towards sterilizing hospital equipment only and not
biological compounds.
because their lower ability to penetrate bacterial spores also causes a potential health hazard to the
operators. On the contrary, it can be used in laboratories, clean rooms, and other fixed installations
in which the primary aim is a significant reduction of the microbial count (disinfection) and not
complete sterilization .
Chemical methods of sterilization fall into two groups:
liquid sterilization, and gas sterilization. The choice of sterilization method is usually dependent on
the application, availability, and regulations.
For example:……
strict protocols are in place for the chemical sterilization of hospital equipment and supplies
because blunders could have serious repercussions such as death.

7. Advantages of chemical sterilization:
1- that it is relatively inexpensive.
2 -fast-acting, and efficient
3-Most often, it does not require expensive and complex equipment
4-Can used alternatively to objects that would damage by highly presur steam or dry heat
steralization.
Disadvantages…
1-Special handling because of flammability toxicity
2- potential health hazard fumes3 more costly than heat
4 -carcinogenic.