Which one is more effective in killing our hand germs- Hand sanitizer or soap?
Which one is more effective in killing our hand germs- Hand sanitizer or soap?
Hand sanitizers are in huge demand in this face of covid -19 and are extremely useful when you don’t have sink and soap nearby.
But is
the fame of hand sanitizers justified?
Most
health officials recommend that the best way to keep our hands virus-free is by
using soap and water. But, when you’re not near a basin, the experts say, hand
sanitizers are the next best thing. Hand sanitizers containing at least 60%
alcohol works maximum according to Centers for Disease Control and Prevention
(CDC) and while applying it must cover all surfaces of the hands with the
product, and rub them together until dry.
You
will be surprised to know that doctors found the link between health and hand
washing much early than scientist knew abut the existence of germs. American
medical reformer Oliver Wendell Holmes and the Hungarian “Savior of Mothers,” Ignaz
Philipp Semmelweis, both connected poor hand hygiene with high rates of
postpartum infections in the 1840s, nearly 20 years earlier than the popular French
biologist Louis Pasteur printed his first germ theory discoveries. In 1966, a
nursing student, Lupe Hernandez published an alcohol-containing, gel-based hand
sanitizer for hospitals. And in 1988, the firm Gojo announced Purell, the first
alcohol-containing gel sanitizer for consumers.
Alcohol
is a very effective disinfectant and its role is to disrupt the outer coatings
of bacteria and viruses. SARS-CoV-2 is an enveloped virus and according to
chemist Pall Thordarson (from University of New South Wales), SARS-CoV-2 is
surrounded by the lipid bilayers which are held together by hydrogen bonds and
hydrophobic interactions. Lipids protects these microorganisms but alcohols (like
ethanol and other alcohols) having a polar and a nonpolar region disrupt these supramolecular
interactions and efficiently ‘dissolving’ the lipid membranes. However, high
concentration of alcohol is recommended to swiftly disrupt protective coating
of the organisms. Therefore, CDC recommends at least 60% alcohol should be
there in hand sanitizers.
Unfortunately,
effect of high concentration of alcohol on your skin is not pleasant. Alcohol dries the skin and break down the
protective layer of oils on your skin. Therefore, hand sanitizer must contain a
moisture to counteract this drying.
WHO
offers two simple formulations for making your own hand-sanitizing liquids.
|
Reagents
for formulation (for small scale production )
|
|
|
1
|
2
|
|
Ethanol 96%
|
Isopropyl
alcohol 99.8%
|
|
Hydrogen
peroxide 3%
|
Hydrogen
peroxide 3%
|
|
Glycerol 98%
|
Glycerol
98%
|
|
Sterile
distilled or boiled cold water
|
Sterile
distilled or boiled cold water
|
Other
moisturizing compounds available in liquid hand sanitizers are poly(ethylene
glycol) and propylene glycol. When an alcohol-based hand sanitizer is rubbed
into the skin, its ethanol evaporates, leaving behind these soothing compounds.
People
who have attempted to get their own gel-based hand sanitizers can tell you that
classic gelling agents like gelatin or agar won’t behave when mixed with the
high concentrations of alcohol that you need to kill viruses and bacteria.
These agents won’t form a gel that’s stable because polar alcohol groups
interrupt the intermolecular bonds. Manufacturers get around this obstacle by
using high molecular- weight cross-linked polymers of acrylic acid. The
covalent cross-links help make a viscous gel that’s resistant to alcohol’s
disruption.
While
most hand sanitizers contain either ethanol or isopropanol, alcohol-free hand sanitizers
are also available commercially. These usually contain antimicrobial compounds
like benzalkonium chloride that helps in protection against bacteria. But
alcohol-free products aren’t endorsed by the CDC for fighting the novel
coronavirus, because it is still doubtful that it can be used successfully
against SARS-CoV-2.
Thordarson
emphasizes that soap and water are still the best option for hand hygiene. Soap
molecules not only break noncovalent interactions that hold viruses and
bacterial cell walls together but can also surround and help remove microbes
from the skin. By using hand sanitizers, you can’t get rid of microbes from the
skin and also aren’t effective against all germs. For example, noroviruses
don't have a lipid membrane coating that can be broken up by alcohol, and the
spores of Clostridium difficile have a tough coating of keratin that can
protect them for years. Alcohol is ineffective when hands are dirty or greasy.
“Alcohol-based
products work,” Thordarson says. “But nothing beats soap.”
References:
Good Information about Senitizer
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