Select the proper engineering controls for your particular containment task
10/01/2002
By Hank Rahe
In my July column, I presented an overview of the four critical elements that compose a successful contamination control system geared for the life sciences: engineering controls, work practices, administrative controls and personal protective elements. We came to an understanding that a proper combination of these elements is required to achieve a safe working environment.
Now, let's see how these four elements can work together to achieve this harmony. Take, for example, the development of a safe workplace for the handling of hazardous pharmaceuticals.
Engineering controls are the primary method recommended by the Occupational Safety & Health Administration (OSHA) to control contamination. Based on the selected engineering controls, the work practices and personal protective equipment needed to provide adequate personal protection can be defined.
The selected engineering controls must have the capability to provide adequate protection levels when supported by work practices and personal protective equipment. Different engineering controls require more, or less, support—the more the support level required, the greater the risk of personnel exposure.
The increased risk comes from the simple fact that work practices require training and that all personnel involved must follow procedures at all times. Job pressures, as well as human nature, may cause people to try new and "unvalidated" ways of doing their job. This "creativity" is often not consistent with proper workplace practices.
An example of two engineering control systems requiring different levels of work practices and personal protective equipment are barrier isolators and Class II biological safety cabinets used in the preparation of hazardous drugs in the pharmacy.
The Class II biological safety cabinet depends on work practices in terms of proper placement of objects inside the cabinet, slow movement in and out of the cabinet and using proper technique while gowning or removing gloves, as well as when cleaning the interior of the cabinet and the disposal of waste.
A properly designed barrier isolator also requires work practices, but tends to be more user-friendly in the preparation of hazardous drugs. The closed design of the barrier isolator removes the restrictions regarding the location and movement of materials within the isolator. Also, the attached sleeves and gloves eliminate the potential for materials to be carried out of the isolator on the operator's gloved hands.
There are no requirements for individual gowns and gloves, and it is possible to clean the entire interior surfaces while waste can be disposed of through a closed system transfer. The barrier isolator systems have less procedural dependence; therefore, it is less likely that the operator will create more risk of exposure by failing to follow the correct work practices.
The less-than-optimal choice of engineering controls results in increased work practices and requires more personal protective equipment. Because the work practices involve both additional training and individual compliance, the result is less efficient operation and a higher risk for exposure when using the Class II biological safety cabinet in this particular example.
The selection of the correct engineering controls to minimize an end user's risk of exposure to hazardous drugs is not a trivial decision and needs to be weighed carefully by both healthcare institutions and regulators of institutions. Weigh all the options and always start your contamination control program with an end in mind.
Hank Rahe is director of technology for Containment Technologies Group and is a member of the CleanRooms Editorial Advisory Board. He can be contacted at [email protected].