The Nature & Necessity of Aseptic Cleaning

In cleanrooms and critical environments, the general principles of cleaning are relatively consistent. The great variation lies in the types of cleaning products required for regulatory classifications and the processes that need to be supported. 

Few other categories of environments and applications yield greater similarities and differences in consumables than “aseptic” and “non-aseptic.” Both require cleanliness as defined by a lack of overall dirt—non-volatile chemical residuess (NVRs), ions, metals and bioburden. But aseptic environments and applications have the additional goal of “asepsis,” the absence of microorganisms such as fungi, bacteria and viruses.

For compounding pharmacies, hospitals and medical device manufacturers that engage in aseptic applications, it’s a deadly serious endeavor. Look no further than 2012’s New England Compounding Pharmacy debacle where 64 people lost their lives and 800 were injured due in large part to substandard aseptic compounding practices. To achieve aseptic conditions and avoid similar disasters for patients, aseptic environments and applications require stringent use of validated sterile cleaning products, and in the case of pharmaceuticals, strict adherence to USP <797>.

A highly controlled manufacturing process

Validated sterile cleaning products can come in many forms, but they are all exposed to precisely controlled levels of gamma irradiation until the DNA of any potential microorganisms would be destroyed. That dosage is carefully monitored and tested for efficacy over time, and the proof of effectiveness is called a Sterility Assurance Level (SAL).

The standard is an SAL of 10^-6, which means there are literally 1,000,000-to-1 odds that your cleaning products are sterile. Finally, the products’ packaging is strictly controlled to maintain the validation of sterility in transport and all individual packages are traceable to their original lots.  

In an effort to cut costs, or in confusion over the difference, some use “gamma irradiated” wipes and sprays in place of their validated sterile counterparts. This is a serious mistake, as these two types of products are created similarly, but not equally.

Gamma irradiated wipes are simply exposed to gamma irradiation—there is no standard of efficacy for sterility. Your odds of having a critical cleaning consumable could be 10-to-1 just as easily as it could be 1,000,000-to-1—there’s simply no way to tell. 

Additionally, even if it was sterilized properly by the manufacturer, it will not be packaged according to validated sterile standards and could become critical cleaning by the time it reaches your facility. Gamma irradiated products cost significantly less than validated sterile products because far less time, effort and care goes into their production.

The Cornerstones of Validated Sterile Cleaning

Aseptic cleanrooms and facilities may vary greatly, but validated sterile clean wipes and isopropyl alcohol (IPA) should be constants in standard operating procedures (SOPs) for aseptic cleaning protocols. Clean wipes serve wide-ranging critical cleaning control tasks, from managing spills and applying chemicals to maintaining the integrity of work surfaces and equipment. 

With extremely low chemical residues, VOCs, and chemical and mineral adulterants—coupled with wide-ranging chemical compatibility—isopropyl alcohol (IPA) is one of the most versatile cleaning agents available. In fact, USP <797> states that 70% IPA  should be applied to everything from supplies and shipping containers to hard surfaces and gloved hands.

Validated sterile wipes come in a variety of formats. Any process may require unique support, and choosing the right wipe for the task can help improve efficiency and reduce the cost of consumables. The following guidelines will help you narrow down your search.

Substrate Construction: Woven or Nonwoven

Woven or knitted substrates are constructed from interlaced loops of yarn. Although woven clean wipes are made from a variety of materials, polyester is the standard for validated sterile knits. Single knit (1-ply) wipers are usually lighter in weight and less resistant to abrasion; heavier wipers are usually double knit (2-ply), which adds further resistance to thread tears and subsequent fiber critical cleaning.

Nonwoven substrates can be made of natural and synthetic fibers and filaments through a variety of processes. Hydroentangling, where a high-pressure water spray compresses and bonds fibers into a homogenous sheet, is the preeminent process for clean wipes as it mitigates the use chemical binding agents that could contaminate processes.

Materials: Synthetics and Blends

Synthetics are typically limited to polyester and polypropylene for validated sterile wipes. They are are cleaner than blends in terms of trace dirt and potential for fiber and particle release. They also possess a greater range of chemical resistances. However, they are less resistant to heat and are hydrophobic, which means they do not absorb aqueous-based liquids.

Blends are typically limited to polyester/cellulose in validated sterile formats. A polyester/cellulose blend combines some of the cleanliness of a synthetic with the hydrophilic—naturally water absorbing—properties of a natural material.

IPA comes in a variety of formats and packaging options, but use in an aseptic environment limits those options considerably.

IPA and Water Blends

Bottled IPA comes in a wide-range of strengths, typically from 100% to 70% and many points in between. It may seem counterintuitive that a lower percentage of IPA would be a more effective disinfectant, but the United States Pharmacopeia (USP) recommends 70% for a reason—drying time. IPA evaporates so quickly that it may not have enough time to disinfect a surface, a significant percentage of water creates a window of time for more effective disinfection.

• DI water has all the ions removed, most notably mineral salts. 
• WFI water is purified to the point where it can be used in injectable (parenteral) drugs, making validated sterile IPA with WFI quality water ideal the most critical tasks.

Use the wipe selection guide above to help determine which validated sterile wipe is best for you to pair with validated sterile IPA.

IPA may be a disinfectant, but that does not mean it will guarantee sterility even when paired with a gamma irradiated wipe.

Use the right wipes for the right tasks

A significant concern in any facility that features cleanroom environments is that a wipe that’s recommended for a lower classification (such as ISO 7) becomes used in a higher class of cleanroom (such as ISO 3). While not as critical, it’s also important to note if consumables made for more critical tasks—and are therefore more expensive—are being used for less critical tasks instead of more economical options. 

In addition to following all relevant site guidelines regarding critical cleaning control procedures, practicing the proper wiping technique can not only making wiping more effective, it can help conserve validated sterile consumables.

With the right outlook, tools and techniques, you can make aseptic critical cleaning control more effective and economical. If you’re looking to enhance your aseptic process support, contact FG Clean Wipes. With more than 50 years of experience, we have helped numerous facilities and businesses improve their approach to validated sterile wiping.