Clean Environments for Sterility Testing

If manufacturers are marketing a product or device as sterile—a sterile label claim—they are going to want to show that it is indeed sterile. To do so, products go through a serious of steps to test for sterility and part or all of those tests may need to be completed in a clean environment.

There can be several levels of clean environments. Two of the most common used at Nelson Laboratories include clean rooms and isolators. Which of the two used depends most frequently on the size of the device or the packaging used.

A clean room environment is just that—a room fitted for sterility testing that provides a clean environment. People and devices go through a fairly complex series of entry points to enter the room ensuring the environment remains clean. Basically we want to make sure we do not contaminate the product or device. The clean room has all of the monitors, cleaning procedures and air filtering necessary to maintain the clean environment for testing.

Isolators on the other hand are environments created out of stainless steel and glass that are accessed by the tester with attached arm length gloves. Testers put their hands into the gloves to access the products to be tested.

Pros and Cons

To determine which clean environment to use is determined by the product and its packaging. Clean rooms have the advantage of space. Large products or products with complex packaging needs a lot of space. It also allows the tester to be in the room and in many situations more than one tester in the room. The biggest drawback is the fact that the largest risk for contamination is the presence of personnel even with the complex clean room entry procedure.

Isolators on the other hand have the advantage of eliminating the risks associated with a human presence. A product or device is placed in the isolator after which the entire environment is sterilized with high concentrations of vaporized hydrogen peroxide forced into the isolator chamber. Testers place their hands and arms into the gloved sleeves to perform the sterilization tests. The isolator is the best for choice for small products or a small number of samples. If packaging is permeable it may not be as good an option as the clean room since the sterilizing gas can penetrate the packaging compromising the sterilization test.

Whether an isolator is used or a clean room, the standards for sterility testing include USP <71> and ISO 11737-2. Under the standard clean rooms are rated between 1 and 8 with the lower rating indicating a cleaner room