by Hank Rahe
As a long-time industry member working within the life sciences, I can appreciate the concern of those who have written in regard to our recent coverage of a study documenting contamination outside Class II BSCs (see Unfiltered, pg. 6).
The comment concerning spills is one that needs to be framed in the terminology common to the pharmacy. In most cases, any escape of the antineoplastic agent is considered a spill. I have witnessed, on more than one occasion, a liquid stream being released and breaching the front opening of the BSC during preparation of a patient dose.
It's true that any material spilled without the pressure of the syringe or internal pressure of the vial would end up contained in the BSC. However, the real world of the preparation area for antineoplastic compounds requires transfers via syringes and often requires that several pharmaceuticals be used in preparing a dose for the patient. Often people do not look at the entire system required to perform a task and quickly blame bad technique.
Within the pharmaceutical world, it is common knowledge that laminar flow technology, the basis for the biological safety cabinet, has a limitation of approximately 30 micrograms of particle matter per cubic meter of airborne contamination because of the required inaction of personnel with the system. This is not a limitation of the laminar flow system, which provides perfect protection until objects are placed in the air stream or individuals interact with the objects placed in the laminar flow environment. Studies indicate that a system that depends on laminar flow technology can only be depended upon to protect individuals working with the environment to the 30-microgram level.
Concerning HEPA filters, it's true that they reduce the amount of material of a particle size less than 0.3 micron. The key question is, if any of the air is vented back to the area, will the system filtration provide workplace protection (i.e., provide a workplace where the amount of antineoplastic agent released is less than the exposure guideline for that compound)? Data from Dr. Anderson's article indicates this may not be the case.
Experiments conducted by a major pharmaceutical manufacturer at the Phoenix Controls facility indicate that both micro-sized particles and vapors can pass through a HEPA filter in quantities that cause concern for such extremely potent compounds as antineoplastics.
Outside venting, or as I call it “dilution is a poor solution,” offers potentially more problems than solutions when working with highly potent compounds. The amount of material required to exceed the exposure guideline, resulting in a potential harmful effect to unsuspecting personnel, can be in the nanogram range. The outcome of such exposure can be a lifetime event for some individuals.
Also, the potential exists for the outside vented airstream to re-enter the building air handling system, or to be concentrated by prevailing wind patterns, to the point that significant amounts would be present in a small area.
It was not the intent of Dr. Anderson's article or the CleanRooms coverage to condemn control measures that may have been helpful in the past. The intent was to present data which indicate that new technology, in terms of a total system with a higher level of integrity, may be necessary to properly protect pharmacy personnel.
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Hank Rahe is director of technology at Contain-Tech in Indianapolis. He has over 30 years' experience in the healthcare industry, as well as four years in academia. He is an expert in the areas of conventional and advanced aseptic processing. He is the past chairman of the board of the International Society of Pharmaceutical Engineers, and is a member of the CleanRooms Editorial Advisory Board.