Why 70% EtOH for cleaning?
abrick at mailhost.tcs.tulane.edu
Fri Jun 2 14:17:47 EST 1995
On 1 Jun 1995 mdcabl at cc.newcastle.edu.au wrote:
> I have a very general question. I was told that 70% EtOH is more effective
> than 95% EtOH for sterlizing and cleaning surfaces. Tradition of course is to
> use 70% to wipe hoods etc. I had assumed 70% was used just to cut costs. Can
> anybody out there tell me why 70% is used? Just curious really.
The bactericidal effects of EtOH result from rapid coagulation of
protein. 70% EtOH reduces the surface tension of bacterial cells better
than absolute. It is believed that absolute EtOH precipitates the
protoplasm at the periphery of the cell retarding penetration.
Isopropyl has slightly better bactericidal activity by
virtue of an even greater ability to reduce surface tension. Alcohol also
has virucidal activity (enveloped), but a negligible effect on spores or
from: AMA Drug Evaluations Annual 1995.
Brick Ayola, Ph.D.
Tulane School of Medicine
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