Naked Science Forum
General Science => Question of the Week => Topic started by: thedoc on 11/10/2016 13:16:55
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Does regular hand soap actually kill germs?
Asked by Dale
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We discussed this question on our show
Connie Orbach put this to Cheryl Trundle from Addenbrooke's hospital...
Cheryl - When you’re talking about hand washing, the important things to know are when to do it, what sort of soap or what agent to use to wash your hands, and how you do it. And really, of those three, the most important is the good technique so it’s how you do it. Any soap will be sufficient, any soap will work, but it’s important you cover all the surface of your hands and you do it for the required length of time, and you need to do it before you touch a patient and after you’ve touched a patient.
Connie - The required length of time? I always thought depended on how much of a rush I was in.
Cheryl - Generally we say between ten and thirty seconds. About the time it takes you to sing Happy Birthday fairly slowly.
Connie - So far Dale, it seems your cleaning lady may have been telling porkies… What about that gesture though?
Cheryl - It’s just so they’re not tempted to touch anything. So they just hold them where they can see them so they’re not touching anything dirty to contaminate them again. Then the water can wash down to the elbow so that the fingertips, which are the important bits, remain clean. It also lets the hands drain a bit so it doesn’t take quite so long to dry them.
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The point of soap is to help wash the bacteria off your hands rather than to kill them, and the soap helps to remove any grease that the bacteria may be held in. It is not necessary to kill them, and the use of anti-bacterial soap merely acts on them once they're down the drain, programming them to have greater resistance to anti-bacterial products in future by killing the ones which are easiest to kill and selecting for the ones that have some degree of natural resistance. No one should be using anti-bacterial soap - it should be banned.
Where bacteria and viruses might actually need to be killed during hand-washing, as in hospitals where staff don't want to transfer any superbug from patient to patient, alcohol can be used, though it doesn't kill everything and could potentially lead to a greater population of resistant bacteria on people's hands.
One of the reasons the problem with superbugs in hospitals is worse today than it was in the past may not be due to greater resistance, but to the removal of brass door handles which are good at killing bacteria, so if you still have them in a hospital, guard them and don't let management replace them.
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I don't think so and there is hand soap available in the market that contains disinfectant.
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Soap is generally not bactericidal (capable of killing bacteria) but it is an extremely effective (in fact probably the most effective) way to disinfect skin; this is because the abrasive action of rubbing soap over the skin, under a stream of running warm water, dislodges and washes away bacteria. It also removes loose skin fragments as well as other surface debris and dirt, which might provide surfaces onto which bacteria can cling.
As a result, we regard proper hand washing (as in for the requisite time and with careful attention to covering all parts of the skin) as the gold standard for infection control in our hospital. Unenveloped viruses, like noro or adenovirus, are immune to the assault of alcohol hand gel, which is effective against some bugs but does nothing to reduce the infectivity of these specific agents. Soap and water dramatically reduces carriage and transmission risk of these tougher agents for the reasons outlined above.
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Hand soap is not the same soap as surgeons use in the hospitals. It is useful for removing stuff from your arms, but if its 100 % - I would certainly not agree with that.
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No, just look at your soap dish...
Soap makes water wetter so it can remove more than water alone...
Depending on what you want to remove with the soap, soap may not be enough...
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@Rodin1880 - how exactly does soap make water "wetter"?
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I am currently on a cruise around the antipodes.
Norovirus has long been the bane of cruises; Chris mentions above that norovirus is not affected by alcohol-based gels.
I see that the focus of shipboard infection control has shifted away from alcohol-based gel to washing your hands with soap and water.
- There are signs showing how to wash your hands for the recommended 20 seconds minimum
- They also emphasise using your own bathroom facilities, instead of shared facilities (whenever possible).
- There are staff everywhere, continually disinfecting surfaces
- Notifying the ships medical staff and quarantine in your cabin were also mentioned in case of infection
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@Rodin1880 - how exactly does soap make water "wetter"?
By reducing the surface tension