Sterile Cleanroom Managment
This article is based on an original publication by Berkshire.
Manufacturing applications in sterile environments require special consideration. It is essential to ensure that the range of cleanroom consumables, from wipers and gloves to swabs and tubing, will not impact the aseptic environment. This is even more critical for environments where the sterility of the final product depends upon sterile processing as opposed to sterilization of the final product. Because introduction of a contaminated consumable could cause failures in the manufacturing process, an understanding of effective sterilization methods is critical.
A number of methods may be used in product sterilization, including autoclaving, e-beam and gamma radiation. There are advantages and disadvantages to each, depending on the application at hand.
The autoclave method employs steam and pressure to achieve sterilization. The drawback to this approach is that the product packaging must be permeable — leading to the repackaging of many products, wasting time and money. Yet because autoclaves are reasonably priced, sterilization can be performed within the home facility, which is particularly effective when working in small batches.
E-beam, or electron beam sterilization methods offer limited utilization for low density products due to a relatively low penetrating power.
The preferred option for high density products and larger batches, gamma radiation offers a higher level of penetrating power to more effectively sterilize through standard product packaging with minimal variation in temperature. This method is particularly useful in the food, cosmetics, and medical industries.
Produced using Cobalt-60 sources, gamma rays are especially suitable for ionization, a type of radiation with enough energy to eradicate orbital electrons without introducing radioactivity. Lethal to microbial life, gamma radiation offers a reliable method of achieving sterility.
Irradiation Alone Is Not Enough
Irradiation is not the same thing as sterilization, and it is not recognized independently by the FDA or pharmaceutical companies as a means of sterilization. While the term "irradiation" implies that a substance has been exposed to gamma rays, it does not ensure that a sufficient dose has been used to achieve sterility. With irradiation alone, no Sterility Assurance Level (SAL) can be determined.
Ability of the product and packaging to withstand irradiation should be qualified prior to beginning a sterility validation process, as substances may weaken or become discolored, rendering them useless. Testing the materials against varying levels of irradiation can determine the maximum tolerated dose.