How Clean is Clean?

When cleaning in a biosafety laboratory, it is important to answer the question, “How clean is clean?” In a laboratory setting the definition of “clean” can mean the difference between life and death in a worst case scenario and between successful weeks of work and lost experiments and product. Even professionals often use the terms decontaminate and disinfect interchangeably.

Let’s compare the definitions given by the Oxford English Dictionary (OED), and the Biosafety in Microbiological and Biomedical Laboratories (BMBL) for the following “clean” words we use.


OED Definition – Neutralize or remove dangerous substances, i.e. radioactivity, or germs from (an area, object, or person).

BMBL Definition – Render an area, device, item, or material safe to handle (i.e., safe in the context of being reasonably free from a risk of disease transmission).


OED Definition – Clean (something) with a disinfectant in order to destroy bacteria.

BMBL Definition – Eliminate nearly all recognized pathogenic microorganisms, but not necessarily all microbial forms (e.g., bacterial spores) on inanimate objects.


OED Definition – Make (something) free from bacteria or other living microorganisms.

BMBL Definition – Make any item, device, or solution free of all living microorganisms and viruses.

The definitions above describe various level of cleanliness. The following chart depicts the order in which the level of “cleanliness” is achieved by term:






———–>    (Disinfect)    ———–>



The level of cleanliness needed in an area is determined by the biological agents used and the types of work being performed. The BMBL outlines various agents, their corresponding biosafety levels (BSL), and proper methods and frequency of cleaning where these agents are present.

Consider alternating acceptable agents in your cleaning strategy to thwart developing resistant agents to ensure continual, effective, broad spectrum disinfection.  Be aware of the pitfalls of relying on 70% ethanol for disinfection and be sure to remain true to regular decontamination by removing absorbent pads daily from bench tops and cleaning around and beneath them. 


Chosewood, L. C., & Wilson, D. E. (2007). Biosafety in microbiological and biomedical laboratories. Diane Publishing.


Shannon Magari, ScD, MS, MPH

Principal and Vice President, Health Sciences
Phone: 315.445.0847