Share thisThe next series of articles in this column will deal with processing waste materials in BSL-3 containment. These processes, the sterilization and decontamination of hazardous material, have a major impact on capital costs and operating budgets, the workflow, and scientific capacity of these laboratories and associated animal facilities. They touch and influence most aspects of the facility and operational program and should be addressed in a rational and careful manner in the planning, construction, and operations of BSL-3 containment in order to achieve your intended risk assessment and operational goals.
The BMBL mainly addresses waste treatment as a secondary barrier function, protecting the environment (including people) outside the laboratory. The autoclave or effluent treatment system or fumigation airlock—the three most common waste treatment systems in a BSL-3 facility—are part of the facility’s secondary barrier systems designed to prevent the escape of hazardous material from the containment boundary. The BMBL defines the requirement for waste treatment in BSL-3 in simple terms:
A method for decontaminating all laboratory wastes should be available in the facility, preferably within the laboratory (e.g., autoclave, chemical disinfection, or other validated decontamination method).1
There are three key principles in this statement: all waste must be decontaminated; the point of decontamination is ideally on the containment boundary but not necessarily so; the method is a validated process. We will deal with each of these principles in turn.
It is important to understand the difference between the terms: decontamination and sterilization. Many people use these terms interchangeably, but they shouldn’t. (It doesn’t help that the piece of equipment most commonly used to decontaminate material is called a sterilizer.) Our definition mainly deals with the efficacy of removal of infectious material (bioburden). Practically speaking, no process is 100% effective at eliminating (terminal killing) 100% of bioburden. All processes, whether for sterilization or decontamination are less than perfect.
Sterilization is the highest standard of effectiveness, and is mainly derived from the healthcare and biopharmaceutical industries. The sterilization process normally refers to terminal killing of 99.99%2 of bioburden including spores. This process must be validated to prove process efficacy. In essence, sterilization is the closest way we get to a completely efficacious process
Decontamination, as it applies to research facilities and biocontainment, has no single specific kill efficacy measurement associated with it. In this context, it is understood to be the use of physical or chemical means to remove, inactivate, or destroy pathogens on a surface or item, to the point where they are no longer capable of transmitting infectious particles and the surface or item is rendered safe for handling, use, or disposal.3 The important consideration when dealing with the decontamination process is that the user must define the needed efficiency of the process, and its primary objective is to provide a process that allows the (waste) material to be handled safely inside and outside the BSL-3 environment.