Which sterilization method is least effective for items that can withstand high temperatures?

Ethylene oxide sterilization is particularly effective for heat-sensitive items that cannot tolerate high temperatures. This method involves exposing items to ethylene oxide gas, which penetrates materials and kills a wide range of microorganisms. However, for items that can withstand high temperatures, this method is less efficient than other options like steam heat sterilization and dry heat sterilization.

Steam heat sterilization utilizes high-pressure steam to kill microorganisms and is highly effective for instruments and materials that are not affected by moisture and heat. On the other hand, dry heat sterilization uses higher temperatures over longer periods to achieve sterilization, which is also suitable for items that can tolerate such conditions.

In comparison, ultrasonic cleaning is a process primarily used to clean items rather than to sterilize them. It uses high-frequency sound waves to agitate a fluid, which can help remove contaminants, but it does not achieve the same level of sterilization as steam or dry heat methods.

Thus, ethylene oxide sterilization is the least effective method when dealing with items that can withstand high temperatures, as its use is designed for more delicate items that could be damaged by higher heat sterilization techniques.