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- Written By: Michael Anissimov
- Edited By: Niki Foster
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2003-2012 Conjecture Corporation
Ethyl alcohol, more frequently known as grain alcohol, works as an antiseptic by coagulating protein, the primary material that makes up cells. Although alcohol cannot coagulate every single cell, it functions well to inhibit the growth and reproduction of many microorganisms, including bacteria, fungi, protozoa, and viruses.
Intriguingly, 70% alcohol is a more effective antiseptic than 100% alcohol. Because alcohol causes protein to coagulate on contact, a 100% solution coming into contact with a microorganism creates a hardened protein wall around the outside of the organism, rather than permeating into its interior. Because microorganisms can be very resilient, this protein shell only causes dormancy rather than death. This can lead to revival and a continuation the cycle of reproduction under the right circumstances. At a purity of 70%, however, the alcohol causes coagulation to occur more gradually, slowing down the microorganism from the inside out.
Human skin cells are more resistant to alcoholic coagulation than most microorganisms. This is why your skin doesn't coagulate if it comes into contact with alcohol. Alcohol is also a good solvent that dissolves and carries away non-organic impurities that are responsible for things like odor. Its antiseptic action does cause a burning sensation on open flesh, as anyone who has ever used alcohol to clean a wound can testify.
Alcohol is an ideal antiseptic because it achieves its goal subtly through coagulation, rather than through some active means like active poisoning or dissolving. Throwing acid on an open wound would only be successful at removing the contaminating microorganisms at the expense of a decent chunk of flesh. Ethyl alcohol should never be confused with methyl alcohol, also known as methanol or wood alcohol. Methyl alcohol is used in industry as a solvent, and should never be used for any medical reason. Even small quantities can cause blindness or paralysis, and large quantities can be fatal.
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Raymond Haak
Post 11 |
My wife and I travel a lot in countries where the water is not acceptable to drink, especially by Americans. i.e. India, China, etc. My question is does whiskey/scotch over ice made in these countries kill most of the bacteria in the water used to produce the ice? Let's assume 2 oz. of 80 (40 percent abv) proof ethyl alcohol in a glass with 6-1 inch cubes of ice. By my calculation, the ice will melt into 6 cu in of water or 3.32 oz of water plus 2 oz of scotch equals a solution of approx. 5.3 oz with 0.8 oz of alcohol or 15 percent alcohol concentration. Will this kill the bacteria and render the solution safe to drink? Thanks. |
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anon124404
Post 10 |
Does the "70 percent works better than 90 percent" rule apply to isopropyl alcohol also? I've always bought 90 percent isopropyl to use as an antiseptic thinking it worked better than 70 percent, but if the coagulation problem exists with both ethyl and isopropyl alcohol than why is 90 percent isopropyl alcohol even sold at all? |
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anon111903
Post 9 |
You can find an EPA-registered disinfectant with 70 percent alcohol, and an FDA-approved antiseptic with the same 70 percent alcohol online. You have to use the EPA-registered disinfectant on surfaces, and the FDA-approved antiseptic on skin, and not vice-versa, because the FDA regulates products that kill germs on people, and the EPA regulates products that kills germs on everything else. Alcohol is one of the few products that is useful as both an antiseptic and as a surface disinfectant, so rather than confuse people with combination approvals which would require lots more government bureaucracy, you figure out what you need the product to do, and then you buy it as either the skin antiseptic, or as the surface disinfectant. If you need alcohol for "cleansing," you can purchase jugs of various strengths of alcohol with neither FDA nor EPA approval. So, even though cleansing alcohol may have the same 70 percent alcohol, you are obliged to use the product according to the package label directions, and use it only for cleaning things, and not for disinfection or as an antiseptic. You can also purchase bottles of 70 percent alcohol as "rubbing alcohol," in which case you would use the product for that purpose, and again, not for disinfection or antiseptic. I suppose you could use it for cleaning. But the rule is, follow the label directions. EPA-approved products for surface disinfection. FDA-regulated products for antiseptics. Home Depot for cleaning alcohol. The supermarket for rubbing alcohol. As a by the way, ethyl (grain) alcohol is safer for use on the skin, because it works at a lower concentration (65-80 percent) than isopropyl (70 to 95 percent). You'll notice on the label of some isopropyl alcohol products that they will tell you not to use it for an extended period of time. The reason for this is because whatever amount of isopropyl alcohol soaks into your skin gets into your bloodstream, and then it's broken down in your liver into a variety of compounds including acetone, which is extremely toxic to your liver. Ethyl alcohol won't do this. |
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anon91250
Post 8 |
I used a small amount of 70 percent Isopropyl alcohol on my face and back where acne grows. The cotton ball at the end made me feel like it was effective because it had a brown dirty looking color. I am going to see if i grow any new pimples tomorrow. This may help me confirm whether or not a small amount of alcohol on the face is effective. |
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anon75688
Post 7 |
Ethanol is effective at eliminating some viruses, but it has no effect on Rhinovirus - the most common cause of the common cold. |
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anon46106
Post 6 |
Which is the better disinfectant: Isop. alcohol or hydrogen peroxide? Did I understand your above comment correctly that hydrogen peroxide kills both bacteria and viruses on surfaces? |
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anon32491
Post 5 |
Is ethyl alcohol or isopropyl alcohol effective against viruses? I have been under the impression that alcohol works against bacteria, not viruses, which are susceptible to hydrochloride or hydrogen peroxide. If that is true, I wonder what is the rationale for asking people to use alcohol rub as a precaution against contracting influenza. In the same note, I am not aware of any epidemiological evidence that influenza is transmitted by touch, e.g., rubbing of eyes by contaminated hands. As a respiratory infection, influenza is transmitted by respiratory droplets or aerosols. So what is the justification for advising the public to wash hands? TW Wong |
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anon30560
Post 4 |
My barbering textbook says 70% ethyl (grain) alcohol, or 90% isopropyl alcohol make useful sanitizers. We're supposed to use products according to packaging directions, but I'll be danged if I can find a bottle of alcohol or rubbing alcohol that gives clear directions on how to use it for a sanitizer. Labels seem rather vague on the whole question. |
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anon10634
Post 3 |
what type of bacteria does can alcohol possibly inhibit? |
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anon9260
Post 2 |
RE:
Posted by: Anonymous 1-what is the ideal % of alcohol as antiseptic?
70% is the ideal solution, more than that and it decreases its efficacy.
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anon8407
Post 1 |
1-what is the ideal % of alcohol as antiseptic?
2-what the difference between propanol, iso propanol & ethanol? which is more effective? 3- does the form of alcohol antiseptic (solution, gel or foam) affect the efficacy of alcohol? |
