Ask A Scientist© Molecular Biology Archive

name         Mary J.
status       educator
age          30s

Question -   I have heard that vinegar can be used as a replacement
for bleach as a disinfectant. I would like to know if this is true,where
there may be proof I can show to others and what strength the vinegar
should be to be most effective.

A "proof" that vinegar is a disinfectant under certain conditions is the
fact that it is used, along with salt [brine], to make and preserve pickles.
In general the highest concentration possible would be most effective. In
the U.S. 5% acetic acid constitutes vinegar and high concentrations are
available only through chemical suppliers and not in the grocery store or
pharmacy.

As a general disinfectant, I would suspect that bleach, because it
disinfects by oxidation, is more effective.

Vince Calder
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The effectiveness of various concentrations depends on
the demands. Undiluted bleach can be used to desinfect
used syringes (used by intravenous drug users) and can
inavtivate HIV completely, however acetic accid does
not inactivate HIV. Less dramatic,  2% is sufficient
to disinfect nebulizers used by patients with cystic
fibrosis at home (these people often suffer from
pseudomonas infections). A solution of 1% acetic acid
can be used to decontaminate the surface of freshly
laid eggs (to remove Salmonella etc. from the
surface).

For decontamination of fresh parsley (known to have
caused  Shigella outbreaks) a dip in vinigar
containing 7.6% acetic acid is sufficient. On the
other hand, an acid drip of beef meat in 2% acetic
acid for decontamination is largely ineffetive against
E. coli O:157:H7 (the 'hamburger bug') because this
organism is acid-tolerant.

In another study the effectiveness of 2% acetic acid
to kill Listeria monocytogenes attached to stainless
steel was found to be low, but could be improved by
the addition of monolaurin (for use on food-utensils,
for example).

All of these studies were under standardized,
experimental conditions and the data are available in
public databases.

Truy Wassenaar,
Curator of the Virtual Museum of Bacteria
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Vinegar is really acetic acid, and will be more effective as a disinfectant
at higher concentrations.  (It would be most effective undiluted.)  In my
opinion, the most convincing comparison to bleach would be an experiment to
see what survives on a surface like a sinktop after cleaning half with bleach
and half with vinegar.  You could swipe a cotton swab on each half of the
sinktop and then onto a Petri dish with a bacterial growth medium.  (I am
assuming you have access to this stuff as an educator).  Grow the plates at
37 Celsius (98 F) overnight and see what kind of furry stuff grows.  You
might want to also do a swipe before cleaning to see how much bacteria you
were starting with before trying to disinfect.

Christine Ticknor, Ph.D.
Case Western Reserve University
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